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1
Vervacke, Céline. "Sensing and Transport Properties of Hybrid Organic/Inorganic Devices." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-152484.
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Over the past two decades, organic semiconductors played a growing part as active layers in several electronic systems such as sensors, field‑effect transistors or light emitting diodes to cite a few. In fact, organic materials offer a high versatility and flexibility. However, pure organic systems often lack stability and robustness, which can be overcome by combining them with inorganic scaffolds.
In this work, a conducting polymer, polypyrrole (PPy) is employed to create new sensor elements based on the combination of both inorganic and organic layers. Electrical measurements, infrared spectroscopy and current sensing atomic force microscopy provides a better understanding of the polymer behavior upon immersion in aqueous solutions. The observed discharge in water leads to a straightforward application of the device as an in‑flow sensor for several acids like HCl, H2SO4 and H3PO4. The wide range of sensing concentrations as well as the low detection limit place the present detector among the best reported so far in the literature.
In a further step to turn towards lab‑in‑a‑tube devices, tubular‑shaped‑integrated microelectrodes are developed by using the rolled‑up technology. As a proof of concept, the successful integration of PPy as an active layer and its use as a gas sensor for volatile organic compounds (VOCs) is demonstrated.
Finally, by adapting the rolled‑up top electrodes, as developed by Bof Bufon et al. for self‑assembled monolayers (SAMs), thin PPy films (<50 nm) are vertically contacted and their electrical characteristics measured as a function of temperature and electric field. From the transport investigations, it is observed that an insulating‑to‑metallic transition occurs in the polymeric film by increasing the bias voltage. Other molecular layers like CuPc can be incorporated in these platforms, opening the way towards emerging organic devices.
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Araujo, Márcio Peres de [UNESP]. "Complexos cofaciais de dirutênio contendo haletos em ponte e fosfinas como ligantes: estudos espectrais, eletroquímicos e de reatividade." Universidade Estadual Paulista (UNESP), 2001. http://hdl.handle.net/11449/105810.
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araujo_mp_dr_araiq.pdf: 1100502 bytes, checksum: 61f93c05d5083f37f2c488086757122a (MD5)O complexo mer-[RuCl3(dppb)H2O] foi utilizado como precursor para a síntese de uma série de complexos binucleares de valência mista, estes apresentam fórmula geral [Ru2Cl5(dppb)(P)2] e [Ru2Cl5(dppb)(P-P)] e forma estudados por técnicas eletroquímicas e espectroscópicas. A maior característica destas espécies é que apresentam acoplamento metal-metal, ou seja transferência de elétrons entre seus centros metálicos em função dessa caracterísitica apresentam absorção na região do infravermelho-próximo do espectro eletrônico, além de dois processos eletroquímicos com separação (ΔE1/2) ~0,60 V, indicativo de forte interação entre os centros metálicos. Complexos com fórmula [Ru2Cl4CO(dppb)(P)2] e [Ru2Cl4(N-het.)(dppb)2] foram sintetizados e caracterizados. Alguns dos complexos obtidos foram testados em reações de hidrogenação de iminas, sendo que alguns mostraram grande atividade. Complexos do tipo [RuCl2(dppb)(N-N)] e [RuCl2(dppb)(N)2] foram utilizados para a redução da acetofenona usando transferência de hidrogênio, as conversões alcançadas foram satisfatórias em função das condições não terem sido optimizadas. Além disso o aqua complexo mer-[RuCl3(dppb)H2O] também foi eficiente para gerar in situ espécies catalíticamente ativas. A reatividade do complexo [Ru2Cl4(dppb)3] com CuCl2.2H2O e [NBu4][AuCl4] foi testada e o produto destas reações foi identificado como [Ru2Cl5(dppb)2]. Estas reações ocorrem via oxidação do complexo de rutênio e posterior fomação do complexo de valência mista contendo três cloretos em ponte. O complexo [RuCl2(PPh3)3] também foi oxidado com excesso de CuCl2.2H2O levando a formação de [CuCl(PPh3)3] (caracterizado por RMN 31P{1H}) e do complexo solvato [RuCl3(PPh3)2MeOH]MeOH (caracterizado por RPE), além destas espécies uma solução amarela é obtida e com a adição de dppm a esta solução o complexo...
The compound mer-[RuCl3(dppb)H2O] was used as precursor for the synthesis of a wide range of mixed valence complexes and present the general formula [Ru2Cl5(dppb)(P)2] and [Ru2Cl5(dppb)(PP)]. These complexes were studied by electrochemical and spectroscopic techniques. The main characteristic of these species is that they present metal-metal coupling or metal-metal electron transfer due to this electron transfer absorptions in the near infrared region can be observed. Cyclic voltammetry studies reveals that these complexes show two reversible electrochemical processes with separation (ΔE1/2) ~0,60 V, which is indicative of strong interaction between metallic centers. Complex with formula [Ru2Cl4(CO)(dppb)(P)2] and [Ru2Cl4(N-het.)(dppb)2] were synthesized and characterized. Some of the compounds synthesized were tested in reactions of imines hydrogenation, and some showed great activity. Complexes of the type [RuCl2(dppb)(N-N)] and [RuCl2(dppb)(N)2] were used for the acetophenone reduction using hydrogen-transfer reactions, conversions were satisfactory due to the conditions has not been optimized. Besides the aqua complex mer-[RuCl3(dppb)H2O] was also efficient to in situ generates active species. The reactivity of the compound [Ru2Cl4(dppb)3] with CuCl2.2H2O and [NBu4][AuCl4] was tested and the product of these reactions was identified as [Ru2Cl5(dppb)2]. These reactions occurs through oxidation and dimerization of the ruthenium complexes to form the mixed valence complex. The compound [RuCl2(PPh3)3] was reacted with excess of CuCl2.2H2O leading to the formation of [CuCl(PPh3)3] (characterized by RMN 31P{1H}) and the compound [RuCl3(PPh3)2MeOH]MeOH (characterized by RPE), besides these species a yellow solution was obtained and with addition of dppm to this solution the compound [Ru2Cl5(dppm)2] is obtained. X-ray structures for the compounds [Ru2Cl5(dppb)2], [Ru2Cl5(dppm)2],...(Complete abstract click electronic access below)
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Araujo, Márcio Peres de. "Complexos cofaciais de dirutênio contendo haletos em ponte e fosfinas como ligantes : estudos espectrais, eletroquímicos e de reatividade /." Araraquara : [s.n.], 2001. http://hdl.handle.net/11449/105810.
Full textAbstract:
Orientador: Alzir Azevedo BatistaBanca: Benedito dos Santos Lima Neto
Banca: Edward Ralph Dockal
Banca: Luiz Antonio Andrade de Oliveira
Banca: Wagner Ferraresi de Giovani
Resumo: O complexo mer-[RuCl3(dppb)H2O] foi utilizado como precursor para a síntese de uma série de complexos binucleares de valência mista, estes apresentam fórmula geral [Ru2Cl5(dppb)(P)2] e [Ru2Cl5(dppb)(P-P)] e forma estudados por técnicas eletroquímicas e espectroscópicas. A maior característica destas espécies é que apresentam acoplamento metal-metal, ou seja transferência de elétrons entre seus centros metálicos em função dessa caracterísitica apresentam absorção na região do infravermelho-próximo do espectro eletrônico, além de dois processos eletroquímicos com separação (ΔE1/2) ~0,60 V, indicativo de forte interação entre os centros metálicos. Complexos com fórmula [Ru2Cl4CO(dppb)(P)2] e [Ru2Cl4(N-het.)(dppb)2] foram sintetizados e caracterizados. Alguns dos complexos obtidos foram testados em reações de hidrogenação de iminas, sendo que alguns mostraram grande atividade. Complexos do tipo [RuCl2(dppb)(N-N)] e [RuCl2(dppb)(N)2] foram utilizados para a redução da acetofenona usando transferência de hidrogênio, as conversões alcançadas foram satisfatórias em função das condições não terem sido optimizadas. Além disso o aqua complexo mer-[RuCl3(dppb)H2O] também foi eficiente para gerar in situ espécies catalíticamente ativas. A reatividade do complexo [Ru2Cl4(dppb)3] com CuCl2.2H2O e [NBu4][AuCl4] foi testada e o produto destas reações foi identificado como [Ru2Cl5(dppb)2]. Estas reações ocorrem via oxidação do complexo de rutênio e posterior fomação do complexo de valência mista contendo três cloretos em ponte. O complexo [RuCl2(PPh3)3] também foi oxidado com excesso de CuCl2.2H2O levando a formação de [CuCl(PPh3)3] (caracterizado por RMN 31P{1H}) e do complexo solvato [RuCl3(PPh3)2MeOH]MeOH (caracterizado por RPE), além destas espécies uma solução amarela é obtida e com a adição de dppm a esta solução o complexo...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The compound mer-[RuCl3(dppb)H2O] was used as precursor for the synthesis of a wide range of mixed valence complexes and present the general formula [Ru2Cl5(dppb)(P)2] and [Ru2Cl5(dppb)(PP)]. These complexes were studied by electrochemical and spectroscopic techniques. The main characteristic of these species is that they present metal-metal coupling or metal-metal electron transfer due to this electron transfer absorptions in the near infrared region can be observed. Cyclic voltammetry studies reveals that these complexes show two reversible electrochemical processes with separation (ΔE1/2) ~0,60 V, which is indicative of strong interaction between metallic centers. Complex with formula [Ru2Cl4(CO)(dppb)(P)2] and [Ru2Cl4(N-het.)(dppb)2] were synthesized and characterized. Some of the compounds synthesized were tested in reactions of imines hydrogenation, and some showed great activity. Complexes of the type [RuCl2(dppb)(N-N)] and [RuCl2(dppb)(N)2] were used for the acetophenone reduction using hydrogen-transfer reactions, conversions were satisfactory due to the conditions has not been optimized. Besides the aqua complex mer-[RuCl3(dppb)H2O] was also efficient to in situ generates active species. The reactivity of the compound [Ru2Cl4(dppb)3] with CuCl2.2H2O and [NBu4][AuCl4] was tested and the product of these reactions was identified as [Ru2Cl5(dppb)2]. These reactions occurs through oxidation and dimerization of the ruthenium complexes to form the mixed valence complex. The compound [RuCl2(PPh3)3] was reacted with excess of CuCl2.2H2O leading to the formation of [CuCl(PPh3)3] (characterized by RMN 31P{1H}) and the compound [RuCl3(PPh3)2MeOH]MeOH (characterized by RPE), besides these species a yellow solution was obtained and with addition of dppm to this solution the compound [Ru2Cl5(dppm)2] is obtained. X-ray structures for the compounds [Ru2Cl5(dppb)2], [Ru2Cl5(dppm)2],...(Complete abstract click electronic access below)
Doutor
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Patarroyo, Rengifo Javier Ivan. "Exploring synthetic strategies for the production of complex inorganic nanoparticles." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666652.
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Los nanomateriales han sido un área intrigante de investigación científica en las últimas décadas, dada sus particulares propiedades físico-químicas que los hacen adecuados para aplicaciones en campos como fotonica, catálisis, biomedicina, remediación ambiental, conversión y almacenamiento de energía, sensores, etc.
Los avances en nanociencia han estado acompañados por mejoras en las capacidades de suministrar control composicional y morfológico de los materiales. La síntesis de nanoparticulas (NPs), donde la ciencia de materiales se dirige con técnicas de química orgánica, son especialmente desafiantes y a veces difíciles de entender y por lo tanto controlar. Esta dificultad surge por el incremento en la complejidad de los mecanismos de mineralización en los cuales los precursores moleculares son transformados en NPs, junto con su fuerte susceptibilidad a la cinética de reacción. Por lo tanto, la pregunta es cómo correlacionar las transformaciones morfológicas que tienen lugar en las NPs durante su formación con el número de procesos fundamentales solapados y reacciones competitivas que están involucradas.
Esta tesis, presenta el desarrollo de metodologías reproducibles para la producción de nanoparticulas sólidas y huecas de metales nobles y de nanoparticulas hibridas de metales nobles-oxidos metálicos (heterodimeros y nanoparticulas tipo core@shell); y además, examinar su comportamiento óptico, quimico y catalítico.Nanomaterials have been an intriguing area of scientific research over the previous few decades because of their unique physical and chemical properties that make them suitable for applications in fields like photonics, catalysis, biomedicine, environmental remediation, energy conversion and storage, sensors, etc. Advances in nanoscience have been accompanied by improvements in the capabilities to deliver compositional and morphological control of materials. Syntheses of nanoparticles (NPs), where material science elements are addressed with organic chemistry precision techniques, are specially challenging and often difficult to understand, hence to control. This difficulty arises from the increased complexity of the mineralization mechanisms in which molecular precursors are transformed into NPs, along with their strong susceptibility to the reaction kinetics. Therefore, the persisting question is how to correlate the morphological transformations that take place in NPs during their formation with the number of overlapped fundamental processes and competing reactions that are involved. This thesis dissertation present the development of reproducible methodologies for the production of high quality solid and hollow noble metal NPs and hybrid noble metal–metal oxide NPs (heterodimer and core@shell NPs); and, in addition, examine their optical, chemical and catalytic behaviour.
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Clancy, Gerald Patrick. "Synthetic inorganic chemistry : novel metallocenes and inorganic fullerenes." Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:9c7f7c35-bb8f-4117-8e2e-e56a9fbcbeab.
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This thesis is divided into two parts. The first part concerns the synthesis and characterisation of substituted metallocene complexes of the transition and main group metals. The second part describes the preparation and characterisation of inorganic fullerene (IF)-related materials. Chapter 1 reviews the chemistry of dialkyl- and diaryl-phosphino substituted cyclopentadienyl complexes of the transition metals. Chapter 2 describes the synthesis and characterisation of the new ligands [M(C5Me4)CH2PMe2] (M = H, Li, Na and K) via the precursors [HC5Me4)CH2PHMe2][X] (X = Cl and PF6). The synthesis, characterisation and chemical reactivity of the compounds [Zr{{η-C5Me4)CH2PMe2}2Cl2 and [Mn{η-C5Me4)CH2PMe2}2] is reported together with supporting evidence for the synthesis of the bimetallic complex [Zr{U+03B7-C5Me4)CH2PMe2}2Cl2PtI2] and the complex [Mn{η-C5Me4)CH2PMe2B(C6F5)3}2]. Chapter 3 provides a brief introduction into the field of main group metallocenes and describes the synthesis and characterisation of the new main group metallocenes [M{η- C5H4)CMe2PMe2}2] (M = Pb and Sn). The B(C6F5)3 adduct [Pb{η-C5H4)CMe2PMe2(B(C6F5)3}2] has also been synthesised. The main group - transition metal bimetallic complex [Pb{η-C5H4)CMe2PMe2}2PtI2 in which the substitutedplumbocene acts as a bidentate ligand, has been characterised by mass spectrometry and 31P{1H}NMR spectroscopy. Chapter 4 provides an introduction into the field of IF-related materials and an overview of the analytical techniques used in their characterisation. Chapter 5 describes the preparation and characterisation of IF-MoS2 and IF-(Nb,W)S2 materials from MoC and the binary oxides Nb8 W9O47 and Nb4W13O47 respectively. A powder X-ray diffraction study of the conversion of WC to WO3-X and the subsequent sulfidisation by H2S to form novel IF-WS2 morphologies is also described. Chapter 6 describes the preparation of amorphous Group 5 metal (V, Nb and Ta) oxides using the metal vapour synthesis technique. These amorphous precursors have been annealed in a reducing atmosphere to form the oxide phases U+03B1-V2O3, NbO2 and TT-Ta2O5 which have been identified by powder X-ray diffraction. Upon reaction with H2S, the crystalline oxides afford layered sulfides of the form MS2 (M = V, Nb and Ta), some of which exhibit behaviour typical of IF-like materials and have been characterised by HRTEM, powder X-ray diffraction and EDX analysis. Chapter 7 outlines the experimental details for the synthesis, characterisation, reactions and compounds described in the preceding chapters. Chapter 8 presents the characterising data for the new compounds described in chapters 2 and 3. Appendix A contains details of the crystallographic data for the structurally characterised compound [Mn{η-C5Me4)CHPMe2}2].
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Otsuka, Takeshi. "Functionalization of Organic-Inorganic Nano-Hybrids Utilizing Inorganic Nanoparticles." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126813.
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Vincent, Paul Robert. "Investigation of inorganic materials for the application of inorganic pigments." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415239.
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Brinza, Daniel L. "Novel inorganic membranes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0019/MQ58444.pdf.
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Ridley, Brent (Brent Alan) 1974. "Printed inorganic transistors." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/62382.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Includes bibliographical references (leaves 146-175).
Forty years of exponential growth of semiconductor technology have been predicated on the miniaturization of the transistors that comprise integrated circuits. While complexity has greatly increased within a given area of processed silicon, the cost per area has not decreased. Current fabrication methods are further hindered by high facility costs and environmentally unfriendly processing. Moving to a new means of semiconductor fabrication may drastically reduce both financial and environmental costs. One such approach is based on the extension of printing techniques to the fabrication of electronic devices. Such printed electronics are envisioned to enable applications in flexible displays and electronic paper, personal fabrication, wearable computing, and disposable medical diagnostics. This dissertation focuses on the development of printable materials, specifically inorganic semiconductor inks. At the outset of this research, organic semiconductors were the only materials known and pursued as printable semiconductors. The ability to process organic semiconductors in common organic solvents makes them amenable to a wide range of printing technologies, but their electrical performance is fundamentally limited and their utility is confined to applications in which only low speeds are required. The goal of this thesis was to demonstrate the feasibility of printing inorganic materials, the same materials that are used to fabricate high quality semiconductor devices. Cadmium selenide was studied as a model inorganic semiconductor and silicon was studied because of its commercial dominance. The insolubility and high processing temperatures of inorganic semiconductors, both of which can prevent
(cont.) their use in printed electronics, were overcome through the use of nanoparticle inks. At very small sizes, nanoparticles can be highly soluble in organic solvents and can have a pronounced melting point depression. Leveraging these size-dependent properties, the first semiconductor nanoparticle inks were developed using cadmium selenide and the first all-printed inorganic thin film transistors were demonstrated. Printed active layers in thin film transistors attained a semiconductor mobility of 1 cm²V⁻¹s⁻¹and an ON/OFF ratio in excess of 10⁴. Further development of inorganic nanoparticle inks and efforts to extend this approach to silicon are described, addressing silicon nanoparticle synthesis, purification, and ink formulation.
Brent Ridley.
Ph.D.
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Price, Adam Jacob. "New inorganic catalysts." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621059.
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Ziegler, Christoph, André Wolf, Wei Liu, Anne-Kristin Herrmann, Nikolai Gaponik, and Alexander Eychmüller. "Modern Inorganic Aerogels." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232333.
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Essentially, the term aerogel describes a special geometric structure of matter. It is neither limited to any material nor to any synthesis procedure. Hence, the possible variety of materials and therefore the multitude of their applications are almost unbounded. Here we present a comprehensive picture of the most promising developments in the field during the last decades.
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Schmidt, Samara. "Estudo da modificação na fotoluminescência em α-Bi2O3 após tratamento térmico assistido por pressão /." Araraquara, 2016. http://hdl.handle.net/11449/136399.
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Orientador: José Arana VarelaCo-orientador: Sergio Mazurek Tebcherani
Co-orientador: Diogo Pascoalini Volanti
Banca: Sonia Maria Zanetti
Banca: Marco Aurélio Cebim
Banca: Maximo Siu Li
Resumo: Este estudo avaliou o efeito de um tratamento tér mico assistido por pr essão sobre as propriedades de fotoluminescência do óxido de bismuto ( α - Bi 2 O 3 ) sintetizado pelo método hidrotérmi co assistido por micro - ondas (HAM ) . O α - Bi 2 O 3 teve sua estrutura determinada através da técnica de Difração de raios X, e com o auxílio de refinamentos pelo método de Rietveld foi possível visualizar que a amostra tratada com pressão possui um ângulo entre os cluster s [BiO 6 ] - [BiO 6 ] ligeiramente maior. A s técnicas de microsc opia el etr ônica de varredura e transmissão possibilitaram a definição da morfologia acicular, tamanho e direção de crescimento dos cristais. A composição química dos materiais foi avaliada pelas espectroscopias Raman e de Fotoelétrons excitados por raios X, onde os espectros Raman mostraram um aumento da intensidade nos modos acima de 284cm - 1 na amostra tratada com pressão, sugerindo uma alteração na densidade eletr ônica. Os espectros XPS em ambas amostras não mostraram a presença de contaminantes, fase secundári a ou íons Bi 2+ . Ambas as técnicas mostraram que as emissões PL do α - Bi 2 O 3 na região de baixa energia (inferior a 2,1 eV) são atribuída s a lacunas de oxigênio que formam estados doadores. As propriedades óticas dos materiais foram avaliadas e comparadas co m o auxílio da técnica de espectroscopia Uv - vis, onde não foi possível verificar nenhuma alteraç ão significativa nas amostras. As propriedades fotoluminescentes das amostras também foram medidas e comparadas . F oi possível verificar que o tratamento térmico assistido por pressão ca usou um aumento angular entre os clusters [BiO 6 ] - [BiO 6 ] do α - Bi 2 O 3, resultando num aumento significativo da intensidade da emissão PL na amostra tratada com pressão . Cálculos teóricos foram utilizados para simular as bandas de va lência e condução dos ma...
Abstract: This research evaluated the effect of a pressure - assisted heat treatment (PAHT) on the photoluminescent (PL) properties of bismuth oxide ( α - Bi 2 O 3 ), which was synthesized by a microwave - assisted hydrothermal (MAH) method. α - Bi 2 O 3 crystal structure was characterized X - ray diffraction, and Rietveld refinements showed the pressure - assisted heat treatment caused an angular increase between the [BiO 6 ] - [B iO 6 ] clusters of α - Bi 2 O 3 . Scanning and transmission electron microscopies allowed defining the morphology (acicular), size and crystal growth direction of crystals. Chemical composition of samples was evaluated by Raman and X - ray photoelectron (XPS) spectr oscopies. Raman spectra showed an increase in the spectrum intensity for frequencies higher than 284 cm - 1 for PAHT samples, which suggests an alteration in the electronic density of crystals. XPS spectra of samples did not show the presence of contaminants, secondary phases and Bi 2+ ions. Both Raman and XPS spectra also showed that the α - Bi 2 O 3 PL emissions in the low - energy region (below 2.1 eV) are attributed to oxygen vacancies that form defect donor states. UV - vis absorption spectra showed no significant difference between samples. The angular increase between [BiO 6 ] - [BiO 6 ] clusters of α - Bi 2 O 3 promoted a significant rise in the electronic density of the material, which was considered as the cause for the increase in PL emission intensity in PAHT samples. F irst - principles total - energy calculations were carried out within the periodic density - functional - theory (DFT) to simulate valence and conduction bands, and the average electronic density in these bands. Theoretical results showed how cluster distortion a lters the polarization of O 2p states, and consequently, the electronic density of crystals.
Banca: Carlos Frederico de Oliveira Graeff
Doutor
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Novak, Sara. "Síntese de materiais Micro/Mesoporosos hierárquicos com estrutura MFI /." Araraquara, 2018. http://hdl.handle.net/11449/153109.
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Orientador: Celso Valentim SantilliCoorientador: Thiago Faheina Chaves
Banca: Regina Célia Galvão Frem
Banca: Wellington Henrique Cassinelli
Resumo: Este trabalho descreve o estudo de uma nova metodologia de síntese para obtenção de zeólitas MFI contendo uma estrutura hierárquica de poros. A porosidade hierárquica é uma propriedade que aumenta a acessibilidade dos reagentes aos sítios ativos dos cristais zeolíticos, sendo importante na melhora do desempenho desses materiais em diversas aplicações como adsorção, catálise e troca iônica. São vários os métodos que abordam a utilização de organossilanos como geradores de porosidade hierárquica mas poucos são os estudos que abordam esses compostos sendo empregados em sistemas de síntese bifásicos, por exemplo, em sistemas microemulsionados. Neste trabalho, a metodologia de síntese consistiu primeiramente na funcionalização de núcleos zeolíticos com três diferentes organossilanos em uma etapa de pré-cristalização a 40oC: octiltrietoxisilano (C8), dodeciltrietoxisilano (C12) e hexadeciltrimetoxisilano (16). A análise estrutural dos materiais foi feita por meio das técnicas de difração de raios X, RMN no estado sólido, termogravimetria e espectroscopia na região do infravermelho, enquanto as propriedades texturais foram avaliadas por fisissorção de nitrogênio e porosimetria de mercúrio. O organossilano C8 apresentou os resultados mais promissores levando a obtenção de zeólitas MFI contendo poros hierárquicos (Vmicro ~ 0,130 cm3g-1, Vmeso ~ 0,211 cm3g-1) e elevadas área externa específica (Sext ~ 273 m2g-1) e hidrofobicidade (θ ~ 140o). Este organossilano foi então utilizado no es... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work describes a new approach to the synthesis to obtain MFI zeolites with hierarchical porosity. Hierarchical porosity is a property that improves the accessibility of reactants to active sites in the zeolite crystals, which is important in different technical applications like as adsorptive or catalytic processes. There are many methods using organosilane to create the hierarquical porosity but are few studies that explores this compounds in two-phase systems like a micro-emulsion systems. In this work, the methodology first consisted of zeolite nucleus functionalization with three organosilanes in a temperature at 40 oC: octyltriethoxysilane (C8), dodecyltrietoxisilane (C12) and hexadecyltrimethoxysilane (C16). The structural analysis of the materials was done by the using of X-ray diffraction, solid state NMR, thermogravimetry and infrared spectroscopy, while the textural properties were evaluated by nitrogen physisorption and mercury porosimetry. The octyltriethoxysilane demonstrated the best results to obtainment of MFI zeolites containing hierarchical pores (Vmicro ~ 0,130 cm3g-1, Vmeso ~ 0,211 cm3g-1), large surface area (Sext ~ 273 m2g-1) and hydrophobic profile (θ ~ 140o). This organosilane was used in the study of addition of an oil phase (dodecane) after the nucleus functionalization. The oil phase was stabilized by functionalized and hydrophobic zeolite nucleus around the oil phase during the hydrothermal crystallization process at 150o C. In this stage, the... (Complete abstract click electronic access below)
Mestre
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Mokrani, Touhami. "The development of inorganic and organic/inorganic membranes for DMFC application." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&.
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A fuel cell is an energy device that converts chemical energy to electrical energy. Low temperature fuel cells, namely the hydrogen fuel cell and the direct methanol fuel cell are preferred amongst other fuel cell types for stationary and vehicular applications, due to their small size and their low operating temperature. The direct methanol fuel cell has several advantages over the hydrogen fuel cell including ease of transport and storage since methanol is a liquid. Since methanol is used directly in the cell there is no need for a reforming process, which results in a less complicated system. However, direct methanol fuel cell are in their infancy and many problems need to be overcome before reaching commercialization. The direct methanol fuel cell has several disadvantages, namely, the sluggish methanol oxidation reaction, the high cost of state-of-the-art proton exchange membranes, the high methanol permeability from anode to cathode and the dependence on the conductivity on membrane water content, which limits their use to temperatures below the boiling point of water, while the need is to work at high temperatures. Attempts to overcome the disadvantages of the state-of-the-art membrane were made in this study, including the development on novel proton exchange membranes and also the modification of existing state-of-the-art membranes.
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Dennis, Shelli R. "Nucleation and growth of inorganic crystals at the organic-inorganic interface /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8050.
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Raval, Hema M. "Non-hydrolytic sol-gel synthesis of inorganic oxides and organic-inorganic hybrids." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326496.
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Zain, S. A. M. "Novel inorganic anion exchangers." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234769.
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Siriluck, Siwarote. "Milling of inorganic materials." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16684/.
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Milling is a ubiquitous process in the glass industry for both feed and recycled materials. A good example of materials of interest is silica, which is available in natural quartzite rock as well as fused silica. Such materials are hard, tough and stiff and require considerable energy for their size reduction. So it is of a great interest to establish the most efficient size reduction method for both amorphous and crystalline structures of such materials. Three sets of silicate materials were chosen for this study: set 1: fused silica (SiO2) and quartzite; set 2: amorphous lithium silicate and crystalline lithium silicate (Li2Si2O5); set 3: amorphous sodium aluminium silicate and crystalline sodium aluminium silicate (NaAl(SiO4)). The test materials properties were characterised for their physical, chemical and mechanical properties. The milling behaviour was studied using a Retsch single ball mill. This was chosen as its dynamics has previously been extensively investigated. The milling results were analysed using a first order rate equation. The milling rate constant (Kp) and grinding limit size (Dl) were determined as a function of humidity. It was found that humidity had no effect on the milling rate. The Rosin-Rammler distribution was found to fit best for the mono mode cumulative particle size distribution. The test materials were cut and prepared in the cube form with a linear dimension of about 7.5 mm. The process of breakage was closely observed. At the start of the milling process, the cubes underwent chipping at the edges and corners. As the process continued, micro-cracks began to propagate through the body of the cube due to fatigue. This resulted in rapid fragmentation and disintegration of the cube, quickly reaching the grinding limit size. For the quartzite and sodium aluminium silicate materials crack propagation took place through inter-crystalline boundaries. After this stage individual grains started to reduce in size until they reached the grinding limit size. In the case of crystalline lithium silicate the spherulitic microstructure causes adhesion of fines to the milling media. The crushed particles do not detach easily from the mother particle and form a thick coating on its surfaces, thereby protecting it. Also the fine powder covers the surfaces of the capsule and stainless steel ball. A new method of milling should be explored, which reduces the adhesion of fines to surfaces. The energy consumption in the shaking ball milling calculated with EDEM simulation. It was found that the input power can be increased with the size of stainless steel ball. At 30 Hz, 11.97 mm steel ball and 1 g of cube samples are calculated the input power as 1.89 W. The mechanical properties of hardness and toughness were characterised by various methods and the breakability index (H/(Kc^2 )) was calculated. It was found that the milling rate correlated well with the breakability index for all the tested materials. The breakability index provides a methodology whereby the milling performance, i.e. milling rate and energy utilization can be predicted from the characterisation of mechanical properties.
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Kyriazi, Eleni. "Inorganic/organic hybrid polymers." Thesis, University of Greenwich, 2005. http://gala.gre.ac.uk/6214/.
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The aims of this project were to synthesise and characterise a range of inorganic/organic hybrid polymers containing pendant vinyl groups and to study their uses as possible fire retardants. The work consisted of several parallel strands: the synthesis of organically modified silicas; the preparation of vinyl containing silsesquioxanes based on the hydrolysis of cyclohexyltrichlorosilane or propylmethacrylatepolysiloxane; the synthesis of latexes by co-polymerisation of either N-Isopropylacrylamide (NIPAM) or styrene with vinyltrimethoxysilane and the intercalation of styrene or NIPAM into montmorillonite. All samples were characterised using a range of instrumental techniques including infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), X-ray diffraction (XRD), elemental analysis, thermal analysis, surface area analysis and electrokinetic analysis. Vinyl modified silicas having large surface areas (about 400m2g-1) were successfully obtained. On calcining at 540°C silicas having surface area in excess of 1000m2g-1 were formed. Both the original organically modified silica and a sample after calcining were incorporated into poly(methylmethacrylate) and these samples were compared with pure poly(methymethacrylate) in a cone calorimeter to study their thermal properties. No significant enhancement to the thermal stability of the polymers was observed when the silica was incorporated. Analysis of the co-polymer latexes were inconclusive, in the case of the products obtained from NIPAM but particles having a narrow size distribution were obtained using styrene. There was no apparent trend in the value of the zeta potential with composition. Analysis of the intercalation of monomers into clays and the synthesis of silsesquioxanes were inconclusive.
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Sgraja, Martin [Verfasser]. "Template based synthesis of organic, inorganic and organic-inorganic hybrid hollow spheres / Martin Sgraja." Aachen : Shaker, 2011. http://d-nb.info/1070151971/34.
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Anderson, Ingrid E. "All-inorganic nanoparticle solar cells /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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Khushalani, Deepa. "Studies of mesoporous inorganic materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35204.pdf.
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Gladden, L. F. "Structural studies of inorganic glasses." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233932.
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The present work has been concerned with a study of the structure of germanium and silicon dichalcogenide glasses. Initially, the aim of this research was to obtain direct structural evidence of reversible photostructural changes in bulk germanium chalcogenide glasses. However, having confirmed the existence of such changes using EXAFS and neutron scattering techniques, it became obvious that a more comprehensive understanding of the as-quenched, annealed glass structure is required before a valid interpretation of the data can be made; in particular, the extent of medium-range order in these systems is of interest. Although limited to few examples at the moment, the potenital of both structural modelling and NMR studies for solving such problems has been investigated in a variety of inorganic glass systems, and these approaches can now be extended to those glasses exhibiting photostructural changes. Modelling studies of the structure of a-SiSe2 have shown that the total correlation function T(r) is sensitive to different structural features in the generated glass structure. The present studies heavily favour a structure based on chains of edge-sharing (SiSe4) tetrahedra. A degree of spatial correlation is required between the chains, such as can only be obtained by short lengths of parallel chains 'pinned' by corner-sharing tetrahedra. 29Si NMR studies of vitreous silica have shown that water, incorporated into the SiO2 network as OH, acts as a major source of spin-lattice relaxation in this system. Numerical methods of self-calibration ('phasing') and removal of data truncation and lineshape apodization effects have been investigated, thereby enabling quantitative information concerning the Si-O-Si bond-angle distribution in silica to be obtained. Although these algorithms are presented with reference to NMR spectroscopy, their extension to other branches of spectroscopy is obvious. NMR has also been used to probe defect states in a-Se. 77Se spin-lattice relaxation time data provide evidence of a defect state (perhaps a VAP) in equilibrium with C10 centres in the glass.
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Hubert, Jason Dominic. "Studies in synthetic inorganic chemistry." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334376.
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Stavrinadis, Alexandros. "Inorganic semiconductor nanoparticles for photovoltaics." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526119.
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Chu, Bryan Tsu-Te. "Carbon nanotube reinforced inorganic matrix." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489422.
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The work described in this thesis concerns carbon nanotube reinforced glass/ceramic nanocomposites. The aim of the research project was to achieve uniform carbon nanotube dispersions in glassy matrices and subsequently measure the physical properties of the materials.
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Thomas, Julie Ann. "Microencapsulation Using Inorganic Wall Materials." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503752.
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Metsios, Ioannis. "Electroluminescence and inorganic phosphor science." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:5856.
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The research is focussed on wide bandgap 11-VI semiconductors, and more specifically on ZnS and CdS, with applications as thin film electroluminescent displays in the expanding display device market. The science of electroluminescent semiconductors and inorganic salt precipitation is combined with a unique, thin film laser processing technique known as laser induced forward transfer or direct writing (the later terminology used mostly in the case of metal films). Zinc sulfide and cadmium zinc sulfide films with a thickness ranging between 70 and 400 nin have been prepared in an aqueous chemical bath, on optically smooth, silica, or silica based, substrates. The chemical bath contained zinc and cadmium chlorides, thioacetamide, and urea, and the most successful combination of concentrations was found to be 2.6 mM, 56.36 mM and 167.71 mM, respectively. The solution was only slightly acidic, with a pH between 5 and 6.5, and a bath temperature of 90 to 92°C (as measured at I cm from the water surface of the bath) was found to be the most efficient. The films were doped with impurities, such as Cu, Ag and Mn in order to achieve specific luminescent characteristics. A KrF excimer laser at 248 nin was used to transfer the films from their original substrate to a new one. The laser pulse was focussed on the chemically deposited films through the back of the transparent silica substrate. The detached film was transported across a gap of 15 µm and attached to the new substrate. A fluence between 0.5 and 0.7 jCM⁻² was found to give the best transfers, and also able to achieve multiple layer transfers over the same area of the target substrate. The transfers were performed in an argon atmosphere of 4x 10⁻² mbar pressure. Ellipsometry and film reflectivity measurements were used to model and determine the film thickness of the chemically deposited films and the values obtained were confirmed by scanning electron microscopy. Ile latter, together with optical microscopy, atomic force microscopy and interferometry were exploited to investigate the structure of the chemically deposited and laser transferred films. It was found that a very thin ZnO film initially adhered to the substrate in the bath, on which the ZnS or CdZnS main film was attached as homogenously grown cluster beads or grown via ion by ion deposition. The homogeneously grown beads had a phase separation, containing the sulfide with the lowest Ksp in the centre, enclosed by highest Ksp sulfides, with the highest one as a shell. The phase separation between CuS and ZnS was also confirmed by extended X-ray absorption fine structure. The elemental composition of the chemically-prepared and laser-transferred films was investigated by energy dispersive X-ray analysis (EDX), inductively coupled plasma mass spectrometry and Raman microspectrometry, while the EDX and Raman methods also helped to confirm the phase separation between US and ZnS. Cathodoluminescence and photoluminescence measurements were employed to investigate the luminescence properties of the films, and the Mn doped films that were annealed at 700°C were found to be the most efficient cathode ray excited phosphors, while the Cu doped phosphors came next in efficiency, performing equally well under an electron or a UV laser beam (from a HeCd laser at 325 rim). Smaller luminescence peaks were also detected in Ag doped films. Transferred films showed similar luminescent properties to their original films, but with lower intensity. Thus the chemical bath deposition and laser transferring were successful, but the methods can be further improved.
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Chimpalee, Narong. "Studies in inorganic trace analysis." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336038.
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Seddon, Annela Mary. "Biomolecular templating of inorganic materials." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268710.
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Gowrishankar, Vignesh. "Nanostructured inorganic / polymer solar cells /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Wexler, Anthony S. Seinfeld John H. Seinfeld John H. "Inorganic components of atmospheric aerosols /." Diss., Pasadena, Calif. : California Institute of Technology, 1991. http://resolver.caltech.edu/CaltechETD:etd-07172007-083859.
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Ridley, Brent 1974. "Inorganic semiconductors for printed transistors." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/29147.
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Thesis (S.M.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1999.Includes bibliographical references (leaves 49-51).
CdSe nanoparticles have been solution deposited and thermally processed into thin film transistor channels, demonstrating for the first time that an inorganic semiconductor can be printed. A peak field effect mobility of 2.05 cm2V-1s-1 1 was observed for a device processed at 350 °C. The highest ON/OFF ratio, found in a different device, was 8.6x10 3 for a 10 to -10 V gate sweep at a drain-source voltage of -5 V. For the same voltage sweep a mobility of 0.26 cm 2V- s- and an ON/OFF ratio of 1.3 x 103 was observed in a single device. Processing temperatures as low as 250 °C were found to produce semiconducting films that displayed a field effect. A new metathetic synthesis was developed to produce pyridine-capped CdSe nanoparticles at sizes below 20 A.
Brent Ridley.
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Clark, Joanna Helen. "Inorganic materials for energy conversion." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569768.
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In an effort to design systems that harvest solar light and convert this into chemical energy, the primary aim of the work presented in this thesis was to develop complex metal oxide materials that were active photocatalysts under visible light. The existing methods for visible light incorporation into photocatalytically active materials are reviewed. Of these, metal to metal charge transfer (MMCT) between bimetallic surface- grafted assemblies was taken as particular inspiration. It was hypothesised that MMCT between metal centres within a bulk complex metal oxide could be similarly applied to yield photocatalytic ally active charge carriers. This approach takes advantage of the stability of bulk systems and the ability to tune the compositions of complex oxide materials. Moreover, it was proposed that MMCT between metal centres located on crystallographically distinct sites of a bulk material would aid charge separation and migration throughout the extended lattice. The optical properties of the RE2 Ti207 (RE = Y, La, Ce, Pr) and Ba2XTizM3015 (X = La, Ce, Pr, Nd, Bi; M = Nb, Ta) series, which include some novel cerium(III) titanates, revealed systematic changes in the electronic structures of these materials. These were rationalised with respect to the energy of Ln 4f states. The proposed electronic structures present the partial achievement of the bulk MMCT hypothesis, with optical transitions from occupied Ce 4f midgap states to the unoccupied primarily Ti 3d conduction band. These Ce3+ /rr" charge transfer materials were inactive photocatalysts, attributed to the presence the Ce 4f-based midgap states that facilitate charge recombination. The double perovskite CaCu3T40IZ, with A-site Cu2+ and B-site Ti4+ cations and whose dielectric properties have been studied extensively in the past, is an ideal candidate for the two site MMCT strategy. Here, the optical and photocatalytic properties, rationalised with the aid of DFT calculations, present the partial achievement of the bulk MMCT hypothesis. Sol-gel derived Pt-CaCu3 Ti4012 is an active photocatalyst toward the visible light photo-oxidation of model pollutants methyl orange (MO) and 4-chlorophenol (4CP). Optical spectra and product analysis show that these reactions proceed via more selective routes than the typical reaction over TiOz P25 under DV light. Interestingly, the products of 4CP photo-oxidation were shown to be dependent on the wavelength of incident light. Cu-doping of BizTiz07 was found to stabilise the pyrochlore structure with respect to the Aurivillius phase Bi4 Ti3012 and to impart significant visible light absorption. Sol-gel derived Pt-BiI.6Cuo.4 Tiz07 photo-oxidised MO under visible light via conventional band gap excitation, as determined by quantum efficiency measurements. In contrast, sol-gel derived Pt-B4 Ti3012 photo-oxidised MO via the excitation of adsorbed MO, and was also active toward 4CP photo-oxidation under visible light. The excitation method, mechanisms and product distributions have been investigated for each of the photo-oxidation reactions presented in this thesis. In particular, the photo- oxidation of MO over some Pt-modified metal oxides has been shown to proceed via excitation of adsorbed MO and not of the semiconductor. Additionally, the mechanism and products of these processes are far more selective than the related DV reactions over TiOz P25, and have been shown to depend to some extent on the semiconductor support.
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Liu, Shuangxi. "NMR studies of inorganic solids." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627317.
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Branton, Philip Michael. "Molecular design of inorganic materials." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/844618/.
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Work on modelling compounds possessing die tetraaza[14]annulene (TAA) fragment is described. Modelling studies have been conducted to investigate both structural and electronic properties, of both single molecules and extended arrays of these compounds. The structural aspects have been investigated using molecular mechanics and crystallographic database investigations. Molecules based on the tetraaza[14] annulene structure have been found to adopt one of four conformations. The geometries of these conformations are planar, saddle-shaped, slightly twisted, and dome-shaped. The complexed metal centre and the arrangement of substituents on the periphery of the ligand, have been found to determine which conformation a molecule adopts. In order to model the compounds, three new atom types have been created for the Universal Force Field. The electronic aspects have been investigated using Hartree Fock based calculations for single molecules and Extended Huckel based calculations for extended systems. The electronics of die single molecules have shown there to be a linear trend in the LUMO energies, although die HOMO energies vary very little. The reason for this trend in the LUMOs is unknown, but appears not to be related to any obvious structural feature.
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Stoppiello, Craig Thomas. "Inorganic synthesis inside carbon nanotubes." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41855/.
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The use of single-walled carbon nanotubes (SWNTs) as test tubes for the encapsulation of metallic nanoparticles (MNPs) and the formation of inorganic nanomaterials has been advanced. A methodology to encapsulate the group 10 and 11 metals inside SWNTs to investigate their properties has been optimised. Each metal interacts with carbon differently at the atomic level, as shown by aberration-corrected high resolution transmission electron microscopy (AC-HRTEM), leading to the promotion of a plethora of different processes stimulated by MNPs under the electron beam. Additionally, interactions between SWNTs and small clusters of the group 10 metals have been examined, revealing marked differences between metal-carbon bonding for each metal. This has allowed for a useful insight into metal-carbon interactions on the atomic level which could have profound implications on the future development of new catalysts or nanoscale devices. Following on from this, a series of chemical reactions with platinum compounds were carried out within SWNTs which have shown SWNTs to be both a very effective reaction vessel and template for the formation of low-dimensional PtX2 (X = I, S) nanocrystals, materials that are difficult to create by traditional synthetic methods. The stepwise synthesis within SWNTs has enabled the formation of the platinum compounds to be monitored at each reaction stage by AC-HRTEM, verifying the atomic structures of the products and intermediates, and also by an innovative combination of fluorescence-detected X-ray absorption spectroscopy (FD-XAS) and Raman spectroscopy, monitoring the oxidation states of the platinum guest compounds within the nanotube and the vibrational properties of the host SWNT respectively. The stepwise synthesis has appeared to offer only limited preparative potential because of the lack of stoichiometric control in the resultant inorganic nanomaterials. A new approach for nanoscale synthesis in nanotubes developed in this study utilises the versatile coordination chemistry of platinum which has enabled the insertion of the required chemical elements (e.g. metal, and halogens or chalcogens) into the nanoreactor in the correct proportions for the controlled formation of PtI¬2 and PtS2 with the exact stoichiometry and structure. FD-XAS has also been used to probe the transformations of Pt(acac)2@SWNT to Pt@SWNT, and Cu(acac)2@SWNT to Cu2Ox@SWNT (where x > 1). It was shown that the temperature of both transformations was significantly lower than required for the same reactions in the bulk, which demonstrates the ability of SWNTs to lower the activation energy by polarising encapsulated molecules. Finally, a variety of novel MNPs and MO¬x¬ (M = Pt, Pd, Ni) materials were encapsulated within hollow graphitised carbon nanofibres (GNFs) and evaluated for the sensing of glucose. MOx@GNFs were revealed to be more active sensors than their corresponding MNPs which can be attributed to the increase in Lewis acidity of the metal centres upon oxide formation. Furthermore, the effectiveness of each metal and their corresponding oxides for glucose detection was found to increase in the order Pt > Pd > Ni which can be attributed to both physical and chemical properties of the respective metals. Overall, this thesis demonstrates that nanotubes can be used effectively to not only investigate chemical transformations on the atomic level, but also act as nano-sized test tubes and templates for the formation of novel, low-dimensional inorganic materials with bespoke structure and composition.
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Nobre, Sónia de Sousa. "Photoluminescent nanostructured organic/inorganic hybrids." Doctoral thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2686.
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Doutoramento em FísicaO presente trabalho propõe-se caracterizar a estrutura e as propriedades de fotoluminescência de materiais híbridos orgânicos/inorgânicos. A origem química e fotofísica subjacente à emissão de luz branca dos diureiasils, híbridos compostos por uma rede siliciosa ligada covalentemente por pontes ureia a cadeias poliméricas, foi estudada fazendo uso de dois compostos modelo que reproduzem, selectivamente, as componentes orgânica e inorgânica daquela rede híbrida. A emissão nos di-ureiasils resulta da convolução de uma componente originada nos grupos ureia com uma outra proveniente dos domínios siliciosos. A comparação entre os tempos de vida das emissões dos compostos modelo com as do híbrido, a dependência do tempo de vida destas emissões com a temperatura e a variação da curva de decaimento associada à emissão dos grupos ureia com o tempo de atraso entre o final da excitação e o início da medida, suportam a ocorrência de transferência de energia entre a componente originada nos domínios siliciosos e a proveniente dos grupos ureia. A taxa de transferência de energia foi quantitativamente estimada considerando os mecanismos de troca (3.7×108 s- 1 ) e dipolo-dipolo (1.3×109 s-1). Esta taxa foi, também, calculada para um diureiasil incorporando um complexo de Eu3+ tendo-se verificado que o canal mais eficiente para a luminescência é: (S0) Híbrido → (T) Híbrido → (T) Ligando → (5D1, 5D0) → 7 F0-4. Um precursor híbrido com cadeias alquílicas e grupos ureia (P12), preparado por catálise àcida ou nucleofílica, deu origem, respectivamente, a uma estrutura lamelar cristalina (L12) e a um material amorfo (A12). Iões Eu3+ foram incorporados nos dois sistemas. Para os híbridos obtidos por catálise nucleofílica, demonstrou-se que a sua morfologia é fortemente determinada pela presença e modos de coordenação dos iões Eu3+. Todos os híbridos são emissores de luz branca. A incorporação de iões Eu3+ diminui o rendimento quântico da rede híbrida, o que indica a existência de transferência de energia rede-iões Eu3+ . Um precursor incorporando bipiridina e grupos ureia foi preparado pelo método sol-gel através de catálise nucleofílica, dando origem a híbridos amorfos. Estes híbridos são caracterizados por uma emissão de banda larga atribuída à sobreposição de três componentes: i) estado tripleto da bipridina, recombinações electrão-lacuna originadas ii) nos grupos ureia e iii) nos domínios siliciosos. Valores de 0.18-0.22 foram obtidos para o rendimento quântico, para excitação no UV/azul. Foi demonstrado que os híbridos podem ser excitados com um LED de INGaN comercial, tornando-os materiais promissores para aplicações em fontes de luz de estado sólido. Os híbridos foram também preparados incorporando iões Eu3+, Gd3+, Tb3+ e Eu3+/Tb3+. Os materiais resultantes são emissores de luz branca onde a emissão intra 4-f dos iões lantanídeo se sobrepõe à emissão da rede híbrida.
The present work focuses on the characterization of the structural and photoluminescence (PL) properties of a series of organic/inorganic hybrids. The photophysical and chemical origin behind the white-light photoluminescent features of amide-functionalized hybrids lacking metal activators (di-ureasils) was studied making use of two model compounds that selectively reproduced the organic and inorganic counterpart parts. The comparison between the lifetimes of the two emissions of the inorganic and organic model compounds with those of the hybrids, the Arrhenius dependence with temperature of the siliceous-related lifetime in the hybrids, and the nonexponential behavior of the decay curve of the siliceous-related emission under lower excitation wavelengths are experimental evidence supporting the occurrence of energy transfer in the hybrids. This energy transfer rate is quantitatively estimated for a di-ureasil, generalizing the ideas proposed by Malta, considering the exchange (3.7×10 8 s-1) and dipole–dipole mechanisms (1.3×10 9 s-1). The energy transfer rates were also calculated for a di-ureasil incorporating a Eu3+ complex and it was found that the most efficient luminescence channel is (S 0)Hybrid → (T)Hybrid → (T)Ligand → ( 5 D 1, 5 D 0) → 7 F0-4. A di-urea cross-linked alkylsilane precursor prepared using HCl induced the formation of a crystalline lamellar structure (L12); when prepared with NH 4F an amorphous material (A12) was obtained. Eu3+ ions were incorporated in the two systems and the unique role played by the Eu3+ ions in the modulation of the morphology of Eu@A12 hybrids was for the first time demonstrated via inhibition of the growth of the siloxane network formed through sol-gel reactions and urea-mediated supramolecular self-assembly. All the hybrids are room temperature multi-wavelength emitters and the incorporation of Eu3+ into the L12 and A12 hybrids induces a decrease in the absolute emission quantum yield values, supporting the existence of hybrid-to-Eu3+ energy transfer. A di-urea cross-linked bipyridine (bpy) precursor prepared by sol-gel synthesis under nucleophilic catalysis, by TBAF and NH 4F, gave rise to amorphous hybrids (termed as H and M). They are characterized by emission spectra that consist of a broad band unequivocally ascribed to a superposition of three distinct components: i) bpy triplet state, ii) electron-hole recombinations originated in the NH/C=O groups of the urea cross-linkages and iii) siliceous nanoclusters. Quantum yield values of 0.22-0.18 were measured under excitation in the long-wavelength UV and blue spectral regions. It was demonstrated that H can be efficiently excited using a commercial LED, placing bpy-hybrids as promising materials for photonics and solid state lighting. M was also prepared in the presence of Eu3+, Gd3+, Tb3+, and Eu3+/Tb3+ and formed hybrids that are room temperature multi-wavelength emitters. This is due to the convolution of the emission arising from the hybrid's emitting centres and the Ln3+ intra-4f transitions. The emission colour is tuned across the CIE diagram depending on the Ln3+ ions and the excitation wavelength.
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Gao, Tongzhai. "Anticorrosive Organic/Inorganic Hybrid Coatings." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1412775013.
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Mao, Runjie. "Heterogenous catalysis of inorganic reactions." Thesis, University of Central Lancashire, 2003. http://clok.uclan.ac.uk/20834/.
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Aluminosilicates, especially zeolite A, Surrey powder and alumina, are efficient and mild catalysts for ligand substitution reactions of inert Cr(" and Co(ffl) complexes. The reaction kinetics for the aquation of chromium(1H) chloride and chromium(llI) bromide hexahydrates, the anation reaction of Cr(H 20)631 by Cl- and the aquation of [Co(NH3)5C1]C12 with and without aluminosilicate catalysts were studied using ion exchange chromatography. Rate constants were determined for each reaction by application of a least squares modelling in Excel. Experimental observations agreed with literature data, that under the conditions employed and without catalysts, the aquation reactions of trans-[CrCl 2(H20)4]Ct2H20 and lrans-[Cr]3r2(H20)4JBr2H20 to [Cr(H2O)6] 3 , follow an I mechanism with a conjugate base pathway, indicating that a weakening of the Cr-X bond is crucial for accelerating the aquation reactions. The aluminosilicate catalysed aquation studies of CrC! j6H2O and CrBr3'6H20 appear to indicate that accessible tetrahedral aluminium species are necessary for successful catalysis of the reactions and the greater the number of these sites the faster the aquation. The aluminosilicates act simultaneously as bi-functional catalysts, i.e. as proton acceptors (base catalysis) and as electron pair acceptors (Lewis acid catalysis). Thus, the two possible activation mechanisms that agree with the experimental observations, appear to be: i) association of a halide ion with an accessible Lewis site (e.g. Al—OH2 and/or (AJ-0)2Cr 4), which is developed from weak base site Al-OH on the surface of the catalyst, enabling the halide to dissociate more readily; ii) base catalysis where the catalyst absorbs H allowing the Cr cation to lose fbrther protons from its aquation sphere, reducing the charge on the complex, weakening the Cr—Cl bond and thus making the halide more labile to substitution. This bi-functional catalysis was confirmed by the anation of Cr(H 2O)63 by Cl- and the aquation of [Co(NH3)5Cl]C12 catalysed by Zeolite A and Surrey Powder. The base catalytic functionality can be classified into two types according to how they increase the pH of the solution environments. The first group including zeolite A and intact montmorillonite clays, has low pzc but high cation ion exchange capacity and so raises the pH to a relatively high degree by proton/metal cation exchange. The second group consists of oxides with high pzc such as y-alumina, which raise the pH of their surrounding solutions by reactions to form surface hydroxyls. For the Lewis acid catalysis function, the three possible anion absorption mechanisms on the clay edges that appear to occur under our experimental conditions (pH !9 4 and in Cr3 solution), are: i) formation of Al—OH2 at low pH, which can attract anions by acid—base ion pairing; ii) formation of AI—OCr2 or (Al-0)2Cr by metal cation binding reactions; and iii) the absorption of anions by exchange with the surface OH groups. The adsorbed Cr3 (e.g. [A]-0]2Cr4) on the edge of the catalysts appeared to be playing the more important role as the Lewis acid sites. Surrey Powder and 5A molecular sieve were successful catalysts for the direct syntheses of potassium and sodium tris(oxalato)chromate(ll1), potassium and sodium tris(malonato)chromate(Ill) and tris(ethylenediamine)chromium(ffl) chloride from chromium chloride hexahydrate in water at room temperature. Although no attempts at optimising these yields were made, all yields of the catalytic syntheses were improved over the un-catalysed reactions.
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D'Elia, Eleonora. "Self-healing organic/inorganic composites." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/42229.
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Nature provides us with amazingly complex and clever systems, structures and substances that make up the world we see around us. We can refer to nature, borrowing its ingenious solutions to solve engineering challenges or improve existing man-made materials. The process of assimilating real- world biological examples into technology is called 'bio-inspiration', and for many years scientists have been attempting to imitate the design of natural materials. This project seeks to mimic some of the complex architectures with outstanding properties found in nature: the shells of molluscs, with extraordinary toughness due to a highly hierarchical structure of platelets on the micro- and nano- scale, and human bone, with its ability to self-heal and regenerate its complex composite organic/inorganic microstructure after fracture. In this work it will therefore be investigated the effect of composite polymer/ceramic structures obtained via a manufacturing technique called freeze-casting, it is observed and optimised the role of the thin interface in self-healing organic/inorganic composites and the composition of the soft supramolecular phase and the inorganic phase is varied in order to obtain structures with properties closer to the behaviour of natural ones. The study couples interface and composite design with mechanical tests to determine interfacial adhesion in order to understand the factors that control the strength of the composite and the effectiveness and timescale of its self-healing. The same self-healing polymer is moreover used in the production of an innovative light composite exhibiting electrical conductivity and compression and flexion sensing capabilities in the attempt to mimic the outstanding properties of skin.
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Chen, Chih-Hsien 1977. "Hybrid organic on inorganic semiconductor heterojunction." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98949.
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Hybrid organic on inorganic semiconductor heterojunctions with a sandwich structure have been fabricated and studied using conjugated polymers. The inorganic semiconductor was n-type silicon substrate. The conjugated polymers used in this work include poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) containing polyhedral oligomeric silsesquioxanes (MEH-PPV POSS), regioregular poly(3-hexylthiophene) (RR-P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT).Current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed to characterize the devices. All the devices displayed a rectifying characteristic. Among these devices, the first ever reported PEDOT doped with BF3 on n-Si heterojunction devices showed the best performance with a rectification ratio around 5.7x105 at +/- 2 V and an ideality factor of 2.3. It is speculated that performance of the devices is inversely proportional to the potential barrier height at the organic-inorganic interface. Other results from this work also suggested that smaller energy level offset between the HOMO of the conjugated polymer and the work-function of anode metal will improve device performance. Contact resistance between the anode and polymer is large (∼MΩ range) and should be further investigated in the future.
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Moldoveanu, Georgiana A. "Crystallisation of inorganic compounds with alcohols." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85627.
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Crystallisation, one of the oldest unit operations, is of major economic importance in the hydrometallurgical industry for the separation and/or production of inorganic metal compounds in the form of good quality crystals, both in terms of purity and size. However, industrial crystallisation techniques usually have high energy requirements (e.g. evaporative crystallisation) and the residual solutions are often extremely corrosive, resulting in elevated operating and maintenance costs. Additionally, the majority of industrial crystallisation methods do not render to the appropriate supersaturation control, therefore the produced salts are agglomerates of fine crystallites with heavy solution entrainment and contamination.In this work, the Solvent Displacement Crystallisation (SDC) technique is investigated as an attractive alternative to the conventional crystallisation methods. SDC involves the addition of low-boiling point, water-miscible organic solvents (MOS) to aqueous solutions to cause salt precipitation based on the salting out effect. The crystals are separated by filtration whereas the solvent is subsequently recovered for reuse by low-temperature distillation. The present work was initiated with the main objective to develop a solid scientific understanding of the SDC process and propose specific applications to hydrometallurgical systems of practical interest.
Criteria for the selection of organic solvents with suitable physical and chemical properties have been established and various compounds screened to determine their amenability to SDC; 2-propanol was selected as an effective salting out agent to cause precipitation of most metallic sulphates of practical interest from acidic solutions and opted for use in further studies. Differences in crystallisation behaviour among the various metal sulphates were attributed to differences in hydration energy (the energy required for a hydrated ion to be separated from its bound water).
None of the tested metal chlorides could be successfully separated from HCl-H2O system with 2-propanol. This was explained in terms of enhanced metal chlorides solubilities in non-aqueous solvents relative to water by formation of chloro-complexes of larger stability constants. The preferential formation of chloro-complexes in mixed aqueous and organic solvents is the result of the almost linear drastic increase in the activity of Cl - with mole fraction organic.
Successful examples of using the SDC method in conjunction with an industrial process involve precipitation of NiSO4·6H2O from copper electrorefining spent electrolytes, residual sulphate removal as gypsum (CaSO4·2H2O) in chloride leaching processes and ZnO separation/NaOH regeneration in the system Na2ZnO2, - NaOH - H2O. By maintaining a low supersaturation (i.e. controlled addition of the solvent to the electrolyte) and heterogeneous crystallisation conditions (use of seed/product recycling), crystal growth is favoured while impurity uptake/contamination is minimised.
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Marín, Beloqui José Manuel. "Solution processed inorganic semiconductor solar cells." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/334407.
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En aquesta tesi, l'estudi optoelectrònica i fabricació de diferents solució de processament de semiconductors inorgànics com ara PBS Quantum Dots i cèl·lules solars perovskita s'han fabricat. Al llarg d'aquesta tesi mesuraments optoelectrònics com fotoinducidas càrrega Extracció (PICE), fotoinducidas transitòria fotovoltaje (PIT-PV), fotoinducidas transitòria fotocorriente (PIT-PC) Laser transitòria Espectroscòpia d'Absorció (L-TAS) s'han realitzat a les cèl·lules solars eficients per tal de estudiar els diferents processos elèctrics interns presents en el dispositiu sota condicions de treball.
Usant aquestes tècniques, el desdoblament dels nivells de Fermi s'han trobat per ser l'origen de la tensió en PBS QD cèl·lules solars (Capítol 2).
A més, en el capítol 4.1 d'un estudi optoelectrònic intensiva s'ha realitzat a les cèl·lules solars perovskita mesoporosos, on es van descobrir decaïments biexponenciales de TPV i càrrega diferencial es va proposar manera tan adequada per obtenir la càrrega generada en el dispositiu.
D'altra banda, els dispositius van ser fabricats utilitzant diferents polímers com HTM, i els resultats proporcionats van confirmar que la regeneració va ser superior al 90%, i que PIT-PV realitzat en condicions de foscor corresponen a la recombinació entre els orificis de la HTM i els electrons en el TiO2, com presentat en el capítol 4.2.
A més, els resultats presentats en el capítol 4.3 mostrar que una capa de Al2O3 monoatòmic alentir el recombinació en el dispositiu d'augment de la tensió del dispositiu.En esta tesis, el estudio optoelectrónico y la fabricación de diferentes solución de procesado de semiconductores inorgánicos tales como PbS Quantum Dots y células solares de perovskita se han fabricado. A lo largo de esta tesis medidas optoelectrónicos como fotoinducidas carga Extracción (PICE), fotoinducidas transitoria fotovoltaje (PIT-PV), fotoinducidas transitoria fotocorriente (PIT-PC) Laser transitoria Espectroscopia de Absorción (L-TAS) se han realizado a las células solares eficientes con el fin de estudiar los diferentes procesos eléctricos internos presentes en el dispositivo bajo condiciones de trabajo. Usando estas técnicas, el desdoblamiento de los niveles de Fermi ha sido encontrado como el origen de la tensión en PbS QD células solares (Capítulo 2). Además, en el capítulo 4.1 de un estudio optoelectrónico intensiva se ha realizado a las células solares perovskita mesoporosos, donde se descubrieron decaimientos biexponenciales de TPV y carga diferencial se propuso manera tan adecuada para obtener la carga generada en el dispositivo. Por otra parte, los dispositivos fueron fabricados utilizando diferentes polímeros como HTM, y los resultados proporcionados confirmaron que la regeneración fue superior al 90%, y que PIT-PV realizado en condiciones de oscuridad corresponden a la recombinación entre los huecos de la HTM y los electrones en el TiO2, como presentado en el capítulo 4.2. También, los resultados presentados en el capítulo 4.3 mostraron que una capa de Al2O3 monoatómico ralentiza la recombinación en el dispositivo de aumento de la tensión del dispositivo.
In this thesis, the optoelectronic study and fabrication of different solution processed inorganic semiconductor such as PbS Quantum Dots and perovskite solar cells have been fabricated. Along this thesis optoelectronic measurements such as PhotoInduced Charge Extraction (PICE), PhotoInduced Transient PhotoVoltage (PIT-PV), PhotoInduced Transient PhotoCurrent (PIT-PC) Laser Transient Absorption Spectroscopy (L-TAS) have been performed to efficient solar cells in order to study the different inner electrical processes present in the device under working conditions. Using these techniques, the splitting of Fermi levels have found to be the origin of the voltage in PbS QD solar cells (Chapter 2). Besides, in chapter 4.1 an intensive optoelectronic study has been performed to mesoporous perovskite solar cells, where biexponential decays of TPV were discovered and Differential Charging was proposed as suitable way to obtain the charge generated in the device. Moreover, devices were fabricated using different polymers as HTM, and results provided confirmed that the regeneration was over 90%, and that PIT-PV performed in dark conditions correspond to the recombination between the holes in the HTM and the electrons in the TiO2, as presented in chapter 4.2. Also, results presented in chapter 4.3 showed that a monoatomic layer of Al2O3 slow down the recombination in the device increasing the device voltage..
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Feierabend, Karl Joseph. "Spectroscopy of atmospherically relevant inorganic acids." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207718.
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Spinu, Maria. "Silicon-based organic and inorganic polymers." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-02052007-081236/.
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Lees, Rachel Jane Elizabeth. "Solvothermal synthesis of novel inorganic materials." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2087.
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Solvothennal and hydrothennal synthesis is widely applied in the generation of . metastable crystalline phases, and is used in this work to prepare a range of novel antimony-sulphide and rare-earth oxy-anion compounds in' the presence of linear, branched and macrocycle amines. The new crystalline phases were characterised using single-crystal X-ray diffraction, elemental analysis, diffuse reflectance spectroscopy and SQUID magnetometry. Transition-metals included in the reactions resulted in the fonnation of both binary antimony-sulphide and ternary transition-metal-antimony-sulphide structures. Binary phases include [Fe(en)3]Sb2Ss.0.55H20, [Fe(en)3hSb4Sg, [T(dien)2]Sb6SIO.xH20 (T= Ni, Co), [Co(en)3]SbgS13 and tNi(en)3]Sb12S19, where discrete [Sb2Sst units, SbS2chains, Sb6SI0 6- and SbgS13 2- layers and a three-dimensional Sbl2Slt framework are charge balanced by transition-I.l1etal-amine complexes. The ternary phases synthesised using tris(2-aminoethyl)amine (tren) and diethylenetriamine (dien) include [Cr(tren)]Sb4S7 chains with [Cr(tren)f+ pendent complexes, and [T(dien)hSblgS30[ T(dien)2] (T= Mn, Fe, Co), in which complex antimony-sulphide chains are bridged via dimeric [T2S2] units to fonn novel layers. The transition-metal ions all exhibit paramagnet~c behaviour and the band gaps of the phases were found to increase from 1.79(4) to 2.46(1) eV with increasing framework density. The first examples of hydrothennal antimony-sulphide reactions using a macrocycle, cyclam, as the structure directing agent resulted in the synthesis of novel , layered and three-dimensional phases of[cyclarnH2]Sb6SIO and [cyclamH2]Sb4S7. By including transition-metal salts in the reaction mixture, it was possible to incorporate transition-metal ions within the macrocyclic rings in [Ni(cyclam)]Sb4S7 and [Co(cyclam)]x[cyclarnH2]J_xSb4S7, where the C02+ occupancy varies between O.08
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O'Brien, Duncan L. J. "Preparation of environmentally-friendly inorganic pigments." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/9591.
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A series of compounds that have potential as environmentally-friendly inorganic pigments have been prepared using solid-state methods. The materials have been characterised using a variety of techniques including powder X-ray diffraction, colour measurements, EDX, Mössbauer spectroscopy and solid state NMR. Materials based on the industrial pigment, ultramarine blue, have been investigated using a variety of methods to determine the source of the favoured red-hue. Industrial materials of different shades as well as laboratory synthesised and ion-exchanged ultramarine materials have been analysed for colour, impurities using bromine insoluble method and structure by Rietveld analysis. ICP analysis has been shown to have limited success in determining the AI:Si ratio for ultramarine materials. The role of small levels of potassium in the formation of red-shade blue and the introduction of impurities by the use of feldspar in the industrial formulation has been confirmed. The investigation of a green pigment based on CuO-B203 mixtures has been investigated by varying the ratios of the two components. In the copper-rich region, the materials produced have similar colour properties to the industrial green standard, chrome oxide. The blue boron-rich materials have relatively poor pigment properties and the colour weakens dramatically on grinding and mixing with diluents such as titanium oxide. The poor acid and water stability of the products suggest that the use of these materials as pigments would be limited. A solid solution in the CoO-A1203-GeO2 spinel system has been investigated. As the germanium level increases, the firing temperature required to produce a pure phase decreases. The samples range in colour from blue at the aluminium-rich end through purple to pink at the germanium-rich end. The use of mineralisers appears to have a favourable effect on the colour of the materials. Rietveld refinement of the materials suggests that the series shows disordering of the cations over both tetrahedral and octahedral sites and that the materials become cobalt deficient as the aluminium level increases. Doping, annealing and mineralisation of the SnO-Nb2O5 series using cation (V, Ca, Ta) and anion (Cl, S) doping has produced two different phases with very different properties. The foordite structure, SnNb2O6 is a very stable stoichiometric yellow phase that shows good temperature and gaseous environment resistance. The pyrochlore phase, SnII2x_N, b2y.S n7yO7_7h, owever is very susceptible to changes in atmosphere and readily undergoes substitution at both anion and cation sites to produce phases that vary in colour from yellow through to red. The product phases have mixed divalent and tetravalent tin across two different sites. Substitution of some of the oxygen with sulfur (to a limit of 0.3 per unit cell) leads to a reddening of the sample and stabilisation of the divalent tin within the structure. Mössbauer analysis indicates the presence of both divalent and tetravalent tin in the compound where the level of tin (IV) decreases on substitution of sulfur. Thermal treatment of both tin samples facilitates a reversible temperature dependent change in the colour of the samples from yellow/orange through to bright red. Temperature dependent XRD analysis has shown that the colour change does not result from a change in the structure.
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Rooke, Joanne Claire. "Oxynitride systems as potential inorganic pigments." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494463.
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Inorganic oxynitride materials, with potential applications as pigments, have been synthesised and characterised in terms of their crystal structure, band gap energies and physical properties using powder X-ray and powder neutron diffraction (PXD,PND), solid state UV-Visible spectroscopy, L*a*b* colour measurements, scanning electron microscopy (SEM), energy dispersive analysis of X-rays and thermal analysis. Oxynitride perovskites, AII,IIIBV(O,N)3, where A is a group 2 or lanthanide metal and B an early transition metal have been synthesised by the direct ammonolysis of stoichiometric metal oxides and carbonates at high temperatures, typically 850°C, with the inclusion of group 1 and 2 metal halide salts acting as mineralisers. Powder X-ray diffraction studies show the synthesised perovskites to have primarily an orthorhombic distortion, crystallising in the space group Pnma, similar to CaTaO2N. Exceptions include compounds crystallising in a rhombohedral system, Ca0.77Eu0.23TaO1.77N1.23 or in a monoclinic system, LaTaON2. PXD profiles have highlighted the presence of a competing pyrochlore phase, which becomes more prevalent as the radius of the divalent and trivalent cations decreases such that perovskite phases for smaller lanthanides do not form. Neutron diffraction studies show that the oxygen to nitrogen ratio in the orthorhombic perovskite is Ca0.5Nd0.5TaO1.5N1.5 and there is a slight ordering of O/N over the two anionic sites. In the octahedra forming the framework, the axial positions have greater nitrogen occupancy, whereas the equatorial positions favour oxygen. In contrast to this, the group 2 substitutions onto the lanthanide position in LaTaON2 yielding A(1-x)LaxTaO(2-x)N(1+x), have shown a random distribution of oxygen and nitrogen over both positions. UV-Visible spectroscopy of these oxynitrides reveal broad reflectance bands and a steep absorption edge, which is directly related to the and gap energy of the compound. By varying the doping levels on the B site with transition elements other than Ta such as Nb, Ti, W and Zr, the colour of the compound can be seen to visibly alter. Solution methods, such as co-precipitation techniques, have been employed to deposit oxide precursors onto mica flakes, which are then fired under flowing ammonia to target thin films of oxynitride pigment on mica to produce interference effects. SEM has shown the presence of two separate morphologies, mica and pigment, thus resulting in unsuccessful depositions. Although the pearlescent nature of mica remains after heat treatment with ammonia, solution methods do not yield the same intense colours seen by the solid state route. This necessitates the use of halide salts to target pigments with high quality hues but this destroys the pearlescent effects seen in mica.
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Key, Philip Henry. "Excimer laser micromachining of inorganic materials." Thesis, University of Hull, 1989. http://hydra.hull.ac.uk/resources/hull:11090.
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