Journal articles: 'Synthèse sol-gel'

1

Khaldoune, Jalal, Monique Bernier, Eric van Bochove, and Michel C. Nolin. "Détection du gel et non-gel du sol en utilisant le radar polarimétrique à synthèse d’ouverture." Canadian Journal of Remote Sensing 34, no. 4 (January 2008): 418–29. http://dx.doi.org/10.5589/m08-031.

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Benhamza, H., A. Bouhaouss, FA Josien, and J. Livage. "Synthèse de matériaux phosphatés par de nouvelles méthodes basées sur le procédé sol – gel." Journal de Chimie Physique 88 (1991): 1875–83. http://dx.doi.org/10.1051/jcp/1991881875.

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Kroke, Edwin, Karl W. Völger, Alexander Klonczynski, and Ralf Riedel. "Eine Sol-Gel-Route zur Synthese von B4C." Angewandte Chemie 113, no. 9 (May 4, 2001): 1751–53. http://dx.doi.org/10.1002/1521-3757(20010504)113:9<1751::aid-ange17510>3.0.co;2-9.

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Khairy, Mohamed, Abdelrahman H. Mahmoud, and Kamal M. S. Khalil. "Synthesis of highly crystalline LaFeO3 nanospheres for phenoxazinone synthase mimicking activity." RSC Advances 11, no. 29 (2021): 17746–54. http://dx.doi.org/10.1039/d1ra02295d.

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Gonçalves, M. Clara. "Sol-gel Silica Nanoparticles in Medicine: A Natural Choice. Design, Synthesis and Products." Molecules 23, no. 8 (August 13, 2018): 2021. http://dx.doi.org/10.3390/molecules23082021.

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Silica is one of the most abundant minerals in the Earth’s crust, and over time it has been introduced first into human life and later into engineering. Silica is present in the food chain and in the human body. As a biomaterial, silica is widely used in dentistry, orthopedics, and dermatology. Recently amorphous sol-gel SiO2 nanoparticles (NPs) have appeared as nanocarriers in a wide range of medical applications, namely in drug/gene target delivery and imaging diagnosis, where they stand out for their high biocompatibility, hydrophilicity, enormous flexibility for surface modification with a high payload capacity, and prolonged blood circulation time. The sol-gel process is an extremely versatile bottom-up methodology used in the synthesis of silica NPs, offering a great variety of chemical possibilities, such as high homogeneity and purity, along with full scale pH processing. By introducing organic functional groups or surfactants during the sol-gel process, ORMOSIL NPs or mesoporous NPs are produced. Colloidal route, biomimetic synthesis, solution route and template synthesis (the main sol-gel methods to produce monosized silica nanoparticles) are compared and discussed. This short review goes over some of the emerging approaches in the field of non-porous sol-gel silica NPs aiming at medical applications, centered on the syntheses processes used.

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Schneider, Andreas, Stefan Kairies, and Klaus Rose. "Synthese von alkoxysilylsubstituierten Cyclophosphazenen und ihre Eigenschaften im Sol-Gel-Prozeß." Monatshefte fuer Chemie/Chemical Monthly 130, no. 1 (1999): 89. http://dx.doi.org/10.1007/s007060050165.

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Ui, Sang-wook, In-seok Choi, and Sung-churl Choi. "Synthesis of High Surface Area Mesoporous Silica Powder Using Anionic Surfactant." ISRN Materials Science 2014 (February 5, 2014): 1–6. http://dx.doi.org/10.1155/2014/834629.

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Over the past several years, synthesized mesoporous nanosilica (SiO2) powders have been developed by many different methods. The methods include precipitation and microemulsion, the Stöber method, chemistry, and technology. In this study, mesoporous silica powders are synthesized by the sol-gel method. The sol-gel method obtains a high purity silica powder; however, the process yields a low percentage. Past syntheses of SiO2 powder precursors are expensive, but this study needs to find a replacement precursor for low cost alternatives. A high surface area was used to form an anion surfactant sodium dodecyl sulfate, which regulates the molar concentration. The particles size variability was changed by the precursor molar ratio of the sodium silicate solution with hydrochloric acid.

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Antonelli, David M., and Jackie Y. Ying. "Synthese von hexagonal gepacktem, mesoporösem TiO2 mit einer modifizierten Sol-Gel-Methode." Angewandte Chemie 107, no. 18 (September 15, 1995): 2202–6. http://dx.doi.org/10.1002/ange.19951071828.

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Carstens, Simon, Ralf Meyer, and Dirk Enke. "Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations." Materials 13, no. 7 (April 10, 2020): 1787. http://dx.doi.org/10.3390/ma13071787.

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This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16–24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

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Drofenik, Miha, Darja Lisjak, and Darko Makovec. "The Synthesis and Properties of Magnetic Nanoparticles." Materials Science Forum 494 (September 2005): 129–36. http://dx.doi.org/10.4028/www.scientific.net/msf.494.129.

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Magnetic nanoparticles are materials of great interest because of the remarkable fundamental properties exhibited by these materials as well as their technological potential in the area of biomedicine and other areas. The technologically useful properties of magnetic nanomaterials are not limited to their structural, chemical or mechanical behaviour, but also involve the phenomena that arise from their finite size and the surface effects that dominate the magnetic behaviour of individual nanoparticles. New techniques that have been developed recently have permitted researchers to produce larger quantities of nanomaterials and characterize them better. Here, some of the most promising procedures are reported, including techniques based on hydrothermal syntheses, sol-gel syntheses, co-precipitation syntheses, mechanochemical syntheses, sonochemical syntheses, spray pyrolysis and microemulsion-assisted syntheses.

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Belet, Artium, Cédric Wolfs, Julien Mahy, Dirk Poelman, Christelle Vreuls, Nathalie Gillard, and Stéphanie Lambert. "Sol-gel Syntheses of Photocatalysts for the Removal of Pharmaceutical Products in Water." Nanomaterials 9, no. 1 (January 20, 2019): 126. http://dx.doi.org/10.3390/nano9010126.

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A screening study on seven photocatalysts was performed to identify the best candidate for pharmaceutical products degradation in water. Photocatalysts were deposited as thin films through a sol-gel process and subsequent dip-coating on glass slides. The efficiency of each photocatalyst was assessed through the degradation of methylene blue first, and then, through the degradation of 15 different pharmaceutical products. Two main types of synthesis methods were considered: aqueous syntheses, where the reaction takes place in water, and organic syntheses, where reactions take place in an organic solvent and only a stoichiometric amount of water is added to the reaction medium. Photocatalysts synthesized via aqueous sol-gel routes showed relatively lower degradation efficiencies; however, the organic route required a calcination step at high temperature to form the photoactive crystalline phase, while the aqueous route did not. The best performances for the degradation of pharmaceuticals arose when Evonik P25 and silver nanoparticles were added to TiO2, which was synthesized using an organic solvent. In the case of methylene blue degradation, TiO2 modified with Evonik P25 and TiO2 doped with MnO2 nanoparticles were the two best candidates.

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Setina, Janina, Alona Gabrene, Inna Juhnevica, and Gundars Mezinskis. "Characterization of Iron Oxide Nanoparticles for Sol-Gel Dip-Coating Method Prepared Thin Films." Advanced Materials Research 704 (June 2013): 275–80. http://dx.doi.org/10.4028/www.scientific.net/amr.704.275.

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The paper describes two methods of syntheses of iron oxides, microstructure and morphology of magnetite nanoparticles. Nanocomposite thin films of SiO2/Fe3O4 have been prepared with sol-gel dip coating technique: dip-coating from SiO2/Fe3O4 sol and encapsulation magnetite between two SiO2 layers. Structural and morphological characteristics of iron oxides particles and prepared film were analyzed by X-Ray Diffraction, SEM, FTIR, DTA, AFM. AFM topography of surface and measurements of roughness has shown that using iron oxide encapsulation between two SiO2 layers to provide the even distribution of iron oxide, results as high quality films with low Rq values 1.5 2.7 nm.

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13

Garnweitner, G., and C. Grote. "Die nicht-wässrige Sol-Gel-Synthese - eine Alternative für die Herstellung hochqualitativer Metalloxid- Nanopartikel." Chemie Ingenieur Technik 82, no. 5 (March 29, 2010): 615–22. http://dx.doi.org/10.1002/cite.200900151.

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14

Müller, C., K. Kraushaar, E. Kroke, and A. V. Patel. "Aminosilan-basierende Sol-Gel-Synthese zum Einschluss von biologischem Material in Hydro- und Xerogelen." Chemie Ingenieur Technik 86, no. 9 (August 28, 2014): 1557. http://dx.doi.org/10.1002/cite.201450117.

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15

Rovai, Riccardo, Christian W. Lehmann, and John S. Bradley. "Oxidfreie Sol-Gel-Chemie: Synthese von Tris(dialkylamino)silazanen aus einem kohlenstofffreien, porösen Siliciumdiimidgel." Angewandte Chemie 111, no. 13-14 (July 12, 1999): 2073–76. http://dx.doi.org/10.1002/(sici)1521-3757(19990712)111:13/14<2073::aid-ange2073>3.0.co;2-6.

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16

Rouhani, Roya, Hamid Reza Aghabozorg, Mohsen Asadi Asadabad, and Hossein Aghabozorg. "Synthesis of Mo, W, and Mo- and W-Doped Multiwall VONTs via Sol-Gel and Hydrothermal Methods." Journal of Chemistry 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/243920.

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Mo, W, and Mo and W were doped into multiwall vanadium oxide nanotubes. The syntheses were performed using sol-gel method followed by hydrothermal method. The synthesized samples were characterized by XRD, SEM, EDX, and TEM techniques. The XRD patterns of the synthesized samples indicated that Mo and W could be doped into VONTs totally up to 50%. The SEM and TEM images showed that the prepared samples have tubular and multiwall morphology and open ends.

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Sheikh, Faheem A., Javier Macossay, Muzafar A. Kanjwal, Abdalla Abdal-hay, Mudasir A. Tantry, and Hern Kim. "Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles." ISRN Nanomaterials 2012 (November 19, 2012): 1–8. http://dx.doi.org/10.5402/2012/816474.

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The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems.

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18

Hintz, W., V. Jordanova, T. Nikolov, and J. Tomas. "Sol-Gel-Synthese zur Herstellung nanoskaliger Partikel aus Titan(IV)oxid– Reaktionskinetische Untersuchung der Peptisationsreaktion." Chemie Ingenieur Technik 75, no. 8 (August 25, 2003): 1132. http://dx.doi.org/10.1002/cite.200390377.

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19

Erigoni, Andrea, and Urbano Diaz. "Porous Silica-Based Organic-Inorganic Hybrid Catalysts: A Review." Catalysts 11, no. 1 (January 8, 2021): 79. http://dx.doi.org/10.3390/catal11010079.

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Hybrid organic-inorganic catalysts have been extensively investigated by several research groups in the last decades, as they allow combining the structural robust-ness of inorganic solids with the versatility of organic chemistry. Within the field of hybrid catalysts, synthetic strategies based on silica are among the most exploitable, due to the convenience of sol-gel chemistry, to the array of silyl-derivative precursors that can be synthesized and to the number of post-synthetic functionalization strategies available, amongst others. This review proposes to highlight these advantages, firstly describing the most common synthetic tools and the chemistry behind sol-gel syntheses of hybrid catalysts, then presenting exemplificative studies involving mono- and multi-functional silica-based hybrid catalysts featuring different types of active sites (acid, base, redox). Materials obtained through different approaches are described and their properties, as well as their catalytic performances, are compared. The general scope of this review is to gather useful information for those approaching the synthesis of organic-inorganic hybrid materials, while providing an overview on the state-of-the art in the synthesis of such materials and highlighting their capacities.

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Erigoni, Andrea, and Urbano Diaz. "Porous Silica-Based Organic-Inorganic Hybrid Catalysts: A Review." Catalysts 11, no. 1 (January 8, 2021): 79. http://dx.doi.org/10.3390/catal11010079.

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Hybrid organic-inorganic catalysts have been extensively investigated by several research groups in the last decades, as they allow combining the structural robust-ness of inorganic solids with the versatility of organic chemistry. Within the field of hybrid catalysts, synthetic strategies based on silica are among the most exploitable, due to the convenience of sol-gel chemistry, to the array of silyl-derivative precursors that can be synthesized and to the number of post-synthetic functionalization strategies available, amongst others. This review proposes to highlight these advantages, firstly describing the most common synthetic tools and the chemistry behind sol-gel syntheses of hybrid catalysts, then presenting exemplificative studies involving mono- and multi-functional silica-based hybrid catalysts featuring different types of active sites (acid, base, redox). Materials obtained through different approaches are described and their properties, as well as their catalytic performances, are compared. The general scope of this review is to gather useful information for those approaching the synthesis of organic-inorganic hybrid materials, while providing an overview on the state-of-the art in the synthesis of such materials and highlighting their capacities.

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21

Kim, Byung, Woongsik Jang, and Dong Wang. "Facile NiOx Sol-Gel Synthesis Depending on Chain Length of Various Solvents without Catalyst for Efficient Hole Charge Transfer in Perovskite Solar Cells." Polymers 10, no. 11 (November 6, 2018): 1227. http://dx.doi.org/10.3390/polym10111227.

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Nickel oxide (NiOx)–based perovskite solar cells (PSCs) have recently gained considerable interest, and exhibit above 20% photovoltaic efficiency. However, the reported syntheses of NiOx sol-gel used toxic chemicals for the catalysts during synthesis, which resulted in a high-temperature annealing requirement to remove the organic catalysts (ligands). Herein, we report a facile “NiOx sol-gel depending on the chain length of various solvents” method that eschews toxic catalysts, to confirm the effect of different types of organic solvents on NiOx synthesis. The optimized conditions of the method resulted in better morphology and an increase in the crystallinity of the perovskite layer. Furthermore, the use of the optimized organic solvent improved the absorbance of the photoactive layer in the PSC device. To compare the electrical properties, a PSC was prepared with a p-i-n structure, and the optimized divalent alcohol-based NiOx as the hole transport layer. This improved the charge transport compared with that for the typical 1,2-ethanediol (ethylene glycol) used in earlier studies. Finally, the optimized solvent-based NiOx enhanced device performance by increasing the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF), compared with those of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)–based devices.

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Wypych, Aleksandra, Izabela Bobowska, Milena Tracz, Agnieszka Opasinska, Slawomir Kadlubowski, Alicja Krzywania-Kaliszewska, Jaroslaw Grobelny, and Piotr Wojciechowski. "Dielectric Properties and Characterisation of Titanium Dioxide Obtained by Different Chemistry Methods." Journal of Nanomaterials 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/124814.

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We made comparison of titanium dioxide powders obtained from three syntheses including sol-gel and precipitation methods as well as using layered (tetramethyl)ammonium titanate as a source of TiO2. The obtained precursors were subjected to step annealing at elevated temperatures to transform into rutile form. The transformation was determined by Raman measurements in each case. The resulting products were characterised using Raman spectroscopy and dynamic light scattering. The main goal of the studies performed was to compare the temperature of the transformation in three titania precursors obtained by different methods of soft chemistry routes and to evaluate dielectric properties of rutile products by means of broadband dielectric spectroscopy. Different factors affecting the electrical properties of calcinated products were discussed. It was found that sol-gel synthesis provided rutile form after annealing at 850°C with the smallest particles size about 20 nm, the highest value of dielectric permittivity equal to 63.7, and loss tangent equal to 0.051 at MHz frequencies. The other powders transformed to rutile at higher temperature, that is, 900°C, exhibit lower value of dielectric permittivity and had a higher value of particles size. The correlation between the anatase-rutile transformation temperature and the size of annealed particles was proposed.

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23

Yeh, Hui-Chun, Pei-Yung Hsu, Ah-Lim Tsai, and Lee-Ho Wang. "Spectroscopic characterization of the oxyferrous complex of prostacyclin synthase in solution and in trapped sol-gel matrix." FEBS Journal 275, no. 9 (April 4, 2008): 2305–14. http://dx.doi.org/10.1111/j.1742-4658.2008.06385.x.

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24

de, Farias, Cecilia Silva, and Thomaz Restivo. "Thermal study of the anatase–rutile structural transitions in sol-gel synthesized titanium dioxide powders." Journal of the Serbian Chemical Society 70, no. 4 (2005): 675–79. http://dx.doi.org/10.2298/jsc0504675d.

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Titanium dioxide powders were synthesized by the sol?gel process using titanium tetrabutoxide as the precursor. The syntheses were performed in saturated aqueous solutions of KCl, CaCl2, NiCl2, CoCl2 and MnCl2, and in dimethylformamaide (DMF) and dimethylsulfoxide (DMSO) solutions. The obtained X-ray diffraction patterns show that all samples were crystalline (anatase phase) with some minor amounts of a brookite phase. It is worth noting that the anatase phase was obtained independent of any previous or further treatment of the synthesized powder, such as hydrothermal or heat treatment. For the titanium dioxide powders synthesized in saturated aqueous solution of metal chlorides (mean crystallite size = 11 nm), the anatase?rutile transition occurred in the range 455?570 ?C, depending on the considered sample, as verified by DTA analysis. In the powders synthesized in DMF or DMSO solutions (means crystallite size = 6 nm), the same structural transition occurred at 485 ?C.

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25

Niu, Ben, Xin Wang, Kai Wu, Xianru He, and Rui Zhang. "Mesoporous Titanium Dioxide: Synthesis and Applications in Photocatalysis, Energy and Biology." Materials 11, no. 10 (October 9, 2018): 1910. http://dx.doi.org/10.3390/ma11101910.

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Mesoporous materials are materials with high surface area and intrinsic porosity, and therefore have attracted great research interest due to these unique structures. Mesoporous titanium dioxide (TiO2) is one of the most widely studied mesoporous materials given its special characters and enormous applications. In this article, we highlight the significant work on mesoporous TiO2 including syntheses and applications, particularly in the field of photocatalysis, energy and biology. Different synthesis methods of mesoporous TiO2—including sol–gel, hydrothermal, solvothermal method, and other template methods—are covered and compared. The applications in photocatalysis, new energy batteries and in biological fields are demonstrated. New research directions and significant challenges of mesoporous TiO2 are also discussed.

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Stoyanova, M. S., R. S. Schäfer, and M. N. Noack. "Charakterisierung und Vergleich der gastrennenden Eigenschaften von Membranen, hergestellt durch Polymer-Sol-Gel-Synthese aus Zr- und Si-Alkoxiden." Chemie Ingenieur Technik 76, no. 9 (September 2004): 1378–79. http://dx.doi.org/10.1002/cite.200490277.

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27

Rezqita, Arlavinda, Simeon Stankov, Jürgen Kahr, Raad Hamid, Irina Gocheva, and Atanaska Trifonova. "Combustion synthesis and electrochemical evaluation of Cr-substituted lithium vanadium (III) phosphate." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 3 (January 8, 2018): 787–93. http://dx.doi.org/10.1177/0954406217750690.

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In this work, the effect of Cr3+ partial substitution on vanadium site in monoclinic lithium vanadium(III) phosphate (LVP) structure resulting in compounds with general formula: Li3V2- xCr x(PO4)3-C ( x = 0, 0.05, 0.1, 0.15) was studied. A two-step sol-gel combustion method was employed in syntheses. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, coupled plasma optical emission spectroscopy, and flash combustion. The electrochemical performance of the active materials was examined through rate capability tests and cyclic voltammetry. The unsubstituted compound LVPC delivers higher capacity compared to the Cr-containing samples due to chromium inactivity in the potential range 3.0–4.4 V vs. Li/Li+. However, the Cr-substituted materials show better overall capacity retention (97–97.6%) in contrast to Li3V2(PO4)3-C (96%) in long cycling.

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Nikolic, Ljubisa, Vesna Nikolic, Miroslav Stankovic, Zoran Todorovic, and Zorica Vukovic. "Porous poly(methylmethacrylate) and poly(methylmethacrylate-co-acrylamide)." Chemical Industry 60, no. 11-12 (2006): 327–32. http://dx.doi.org/10.2298/hemind0612327n.

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The characteristics of two types of porous polymers: poly(methyl methacrylate) and copolymers of methyl methacrylate and acrylamide were investigated in this study. Poly(methyl methacrylate) was synthesized in suspension, using ethylene glycol dimethacrylate as the cross-linking agent, poly(vinyl pyrrolidone) as the protective colloid, and benzoyl peroxide as the initiator. The synthesis of poly(methyl methacrylate-co-acrylamide) was initiated in emulsion in the presence of dioctyl sulfosuccinate sodium salt, followed by a sol-gel process, and completely reacted to the solid state. Potassium persulfate was used as the initiator, and tetramethylol glycoluril as the cross-linking agent. Both types of syntheses were carried out in the presence of ethyl acetate. The porosity, specific surface and distribution of the pore sizes of the obtained polymers were determined by mercury porosimetry. The polymers were used as inert carriers for the immobilization of enzymes and whole cells of Saccharomyces cerevisiae yeast.

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Phulé, Pradeep P. "Sol-gel synthesis of ferroelectric lithium tantalate ceramics: FTIR investigation of the molecular modification of tantalum ethoxide." Journal of Materials Research 8, no. 2 (February 1993): 334–38. http://dx.doi.org/10.1557/jmr.1993.0334.

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Several sol-gel syntheses make use of “additives” in the sol-preparation step. These additives can react with metal alkoxides causing important structural changes. In order to demonstrate the nature of the reactions involved in the molecular modification process, a model system based on Ta(OC2H5)5, acetic acid and acetylacetone (as modifiers), was studied using FTIR spectroscopy. At room temperature, both modifiers react with the ethoxide to cause formation of new organotantalum precursors. The acetic acid modification was observed from the characteristic symmetric and asymmetric vibrations of the COO groups. The average difference in wave numbers (δv = vasymm – vsymm) between the two of 140 cm−1, observed for different ratios of ac/Ta, signifies a bridging nature of the acetate group. For ac/Ta ≥ 1, formation of ethyl acetate, probably as a result of the reaction between ethanol and excess acetic acid, was also observed using FTIR. Results of the acetylacetone modification showed the enol form of acetylacetone which has its v(C–O) and v(C–C) vibrations centered around 1625 cm−1, split into two bands at 1581 and 1518 cm−1, respectively, indicative of chelation of the acetylacetanate ligand to Ta. In the case of acetylacetone modification, the formation of ethanol was confirmed by FTIR analysis of the liquid fraction distilled at ∼80 °C.

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Yahya, Noorhana, Poppy Puspitasari, Krzysztof Koziol, and Giuseppe Pavia. "New Approach to Ammonia Synthesis by Catalysis in Magnetic Field." Journal of Nano Research 16 (January 2012): 119–30. http://dx.doi.org/10.4028/www.scientific.net/jnanor.16.119.

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Ammonia production is a capital-intensive industry as it requires high temperature (400-500oC) and also high pressure (150-300 bar) for its daily operations. An earnest effort was made to synthese ammonia gas using an in-house designed microreactor. The production of ammonia was carried out in a magnetic field reaction zone, with the reaction temperature of 30°C - 280°C and ambient operation pressure. Mn0.8Zn0.2Fe2O4 nanoparticles, synthesized using the sol gel method, were used as the catalyst for the ammonia synthesis. XRD confirmed the single phase ferrites and FESEM images revealed nanofibre-like morphology when sintered at 700oC in argon gas. Electron diffraction was performed using HRTEM and obtained diffraction patterns confirmed the crystal structure of the catalyst. By using the Kjeldahl method it was found that the reaction carried out in 1 Tesla magnetic field gave approximately 46% ammonia yield. The proposed new method could be appealing for ammonia manufacturers due to highly economical implication which may offer urea producers a potential contender in the competitive market place.

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Ruffo, Antonia, Maria Cristina Mozzati, Benedetta Albini, Pietro Galinetto, and Marcella Bini. "Role of non-magnetic dopants (Ca, Mg) in GdFeO3 perovskite nanoparticles obtained by different synthetic methods: structural, morphological and magnetic properties." Journal of Materials Science: Materials in Electronics 31, no. 20 (September 14, 2020): 18263–77. http://dx.doi.org/10.1007/s10854-020-04374-8.

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AbstractGdFeO3 perovskite attracted large interest in different fields thanks to peculiar magnetic and optical properties that are further tunable by means of doping processes and achievable on both Gd and Fe sites or by properly choosing the synthesis routes. In this paper, nanometric GdFeO3 compounds, undoped and doped with diamagnetic Ca2+ and Mg2+ ions, were synthesized by microwave assisted, sol–gel, and polyol syntheses and characterized by X-ray diffraction, showing solid solutions formation. Raman spectroscopy allowed us to confirm, from peak enlargements, the Ca and Mg substitution on Gd and Fe sites, respectively. The magnetic data showed the presence of magnetic domains as consequence of doping with diamagnetic ions, which seem to play a crucial role in the magnetic activity of the compounds. A superparamagnetic behaviour is evidenced; nevertheless, its intrinsic character is not definitely demonstrated. Indeed, the possible presence of traces of magnetic impurities, which are easily obtainable in these samples, such as iron oxides, must be taken into account.

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Ali, Wael, Valbone Shabani, Jochen S. Gutmann, Thomas Mayer-Gall, Omid Etemad-Parishanadeh, Alaa Salma, and Torsten Textor. "Stickstoff- und phosphormodifizierte Verbindungen für den Sol-Gelbasierten Flammschutz von Textilien." Technische Textilien 64, no. 3 (2021): 78–81. http://dx.doi.org/10.51202/0323-3243-2021-3-078.

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Im IGF-Projekt Nr. 19617 N wurden stickstoff- und phosphorsubstituierte Alkoxysilane hergestellt und ihre flammhemmenden Eigenschaften für Textilien untersucht. Die Synthesen erfolgten nach unterschiedlichen Strategien wie der Klick-Chemie und der nukleophilen Substitution kommerziell erhältlicher Organophosphorverbindungen mit aminobasierten Trialkoxysilanen und/oder Cyanurchlorid. Diese neuartigen, halogen- und aldehydfreien Flammschutzmittel wurden auf Stoffe aus Baumwolle (BW), Polyethylenterephthalat (PET), Polyamid (PA), sowie Mischgeweben daraus mit der industriell etablierten Pad-Dry-Cure-Technik und mittels Sol-Gel-Verfahren aufgetragen. Die flammhemmenden Eigenschaften wurden mit den Prüfverfahren nach EN ISO 15025 (Schutzkleidung – Schutz gegen Hitze und Flammprüfverfahren für begrenzte Flammenausbreitung) bewertet. Eine gute Schwerentflammbarkeit der hybriden organisch-anorganischen Materialien wurde bei einer geringen Menge von 3-5 Gew.-% auf Baumwollgeweben erreicht. Darüber hinaus konnten die Wasserlöslichkeit und die Waschbeständigkeit durch die an das Phosphoratom gebundenen funktionellen Gruppen und durch die Optimierung der Härtungstemperatur kontrolliert werden. Insgesamt zeigte das Forschungsprojekt, dass N-P-Silane sehr gute permanente Flammschutzmittel für Textilien sind.

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Li, Hao, Laurence Raehm, Clarence Charnay, Jean-Olivier Durand, and Roser Pleixats. "Preparation and Characterization of Novel Mixed Periodic Mesoporous Organosilica Nanoparticles." Materials 13, no. 7 (March 28, 2020): 1569. http://dx.doi.org/10.3390/ma13071569.

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We report herein the preparation of mixed periodic mesoporous organosilica nanoparticles (E-Pn 75/25 and 90/10 PMO NPs) by sol-gel co-condensation of E-1,2-bis(triethoxysilyl)ethylene ((E)-BTSE or E) with previously synthesized disilylated tert-butyl 3,5-dialkoxybenzoates bearing either sulfide (precursor P1) or carbamate (precursor P2) functionalities in the linker. The syntheses were performed with cetyltrimethylammonium bromide (CTAB) as template in the presence of sodium hydroxide in water at 80 °C. The nanomaterials have been characterized by Transmission Electron Microscopy (TEM), nitrogen-sorption measurements (BET), Dynamic Light Scattering (DLS), zeta-potential, Thermogravimetric Analysis (TGA), FTIR, 13C CP MAS NMR and small angle X-ray diffraction (p-XRD). All the nanomaterials were obtained as mesoporous rodlike-shape nanoparticles. Remarkably, E-Pn 90/10 PMO NPs presented high specific surface areas ranging from 700 to 970 m2g−1, comparable or even higher than pure E PMO nanorods. Moreover, XRD analyses showed an organized porosity for E-P1 90/10 PMO NPs typical for a hexagonal 2D symmetry. The other materials showed a worm-like mesoporosity.

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Pfeifer, Mirko, Thomas Schwarz, Pengfei Cao, and Klaus Stöwe. "Reaction Analyses Based on Quaternary Metal/Metal Oxide Catalyst Testing in Micro-Structured Reactors Using Combinatorial High-Throughput Methods for Power-to-Gas Applications." Catalysts 11, no. 1 (December 23, 2020): 6. http://dx.doi.org/10.3390/catal11010006.

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To optimize the Sabatier process, quaternary supported catalyst materials are synthesized and tested. The syntheses are performed by the industrially established, reproducible and automated methods of impregnation and sol–gel synthesis. The screening of the 588 quaternary catalysts is carried out in a specially designed 10-fold parallel gas flow micro-structured reactor as wall catalysts in sequential operation mode at a temperature of T = 573 K and a pressure of p = 15 bar. For the description of the activity, the reaction parameters CO2 conversion, CH4 yield, and CH4/CO2 selectivity are used. These are determined by analyses of the gas phase composition using µGC-FID. The catalysts with the highest activities are validated in a micro-structured reactor with similar characteristics as the screening reactor in the temperature range between T = 573–673 K and a pressure of p = 15 bar. Characterization by powder X-ray diffraction, Raman spectra, and scanning transmission electron microscopic images data on the phase and element distribution after calcination and reduction was conducted.

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Mohammadi, Sayed, Hooshang Hamidian, and Zahra Moeinadini. "Separation of trace amounts palladium by SiO2/TiO2/Ce nanoparticles prior to flame atomic absorption spectrometry determination in anodic slime and wastewater samples." Open Chemistry 11, no. 11 (November 1, 2013): 1749–56. http://dx.doi.org/10.2478/s11532-013-0315-3.

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AbstractIn the present work, a new SiO2/TiO2/Ce, nanoparticle was synthesed using sol-gel method and evaluated as an adsorbent for preconcentration trace amounts of Pd(II) ions. The characterization of the nanoparticles has been studied by transmission electron microscope and X-ray diffraction. The preconcentration method is based on palladium adsorption onto the surface of nanoparticle at pH 8.5. The main factors affecting Pd(II) adsorption, such as pH of sample solution, concentration and volume of eluent, sample volume, interfering of the coexisting ions and flow rate of sample and eluent were investigated and optimized. At optimum conditions, linearity was maintained between 4.0 to 1000.0 ng mL−1. Detection limit based on 3Sb/m was 2.3 ng mL−1. Seven replicate determinations of a solution containing of 12.5 µg palladium gave a relative standard deviation ±1.7%. According to the Langmuir linear model, the maximum adsorption capacity of palladium was found to be 34.5 mg g−1. Finally, the feasibility of the proposed method for Pd(II) determination was assessed by analysis of certified reference materials, anodic slime and wastewater samples and satisfactory results were obtained.

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Startek, Kamila, Anna Szczurek, Thi Ngoc Lam Tran, Justyna Krzak, Alicja Bachmatiuk, and Anna Lukowiak. "Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil." Coatings 11, no. 5 (May 14, 2021): 573. http://dx.doi.org/10.3390/coatings11050573.

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The reported work was focused on sol–gel-derived organically modified and fluorinated silica coatings deposited on elastic polymeric foil. The structure and topography of the coatings were tested by infrared spectroscopy and microscopic studies. The functional properties were determined using thermal analysis, surface analysis, and oxygen permeability tests. The barrier feature of the investigated materials against oxygen was correlated with the properties of the coatings. The hybrid (organic–inorganic) structure of the coatings was proven, demonstrating the presence of a silica network modified with alkyl and fluoroalkyl groups since precursors with the isooctyl group or different lengths of the fluoroalkyl chains were used for the syntheses. The coatings were free of defects and had a smooth surface except for the sample containing the longest fluoroalkyl chain (perfluorododecyl group), which showed a wrinkle-like surface. The hydrophobic character of the coatings increased, whereas the oxygen permeation coefficient values decreased (reaching a fourfold lower coefficient in comparison to the bare substrate) with a higher content of the fluorinated carbon atoms in the structure. The results were enriched by the information from the thermomechanical analysis as well as nanoindentation and scratch tests giving values of the glass transition temperature, thermal expansion coefficient, coatings adhesion, and hardness of the investigated systems.

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Shahbazi, Pariya, Mahmood Kazemzad, and Amirali Yuzbashi. "Growth of Carbon Nanotube on the Ni-Mesoporous Alumina Catalysts for Use as Adsorbent." Advanced Materials Research 829 (November 2013): 559–62. http://dx.doi.org/10.4028/www.scientific.net/amr.829.559.

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Ordered mesoporous materials with high specific surface area and large pore volume have high potential for commercial applications in adsorption and catalysis. In this study, ordered mesoporous alumina (γ-alumina) with high thermal and chemical resistance was synthesized by the sol-gel method using various organic compounds, i.e. aminoacids and carboxylic acids as template. The obtained data showed that γ-Al2O3 produced in the presence of carboxylic acids as template results in very well catalytic activities for CNT growth. The best results obtained using Ni catalysts supported on alumina at a temperature of 900 °C. Since the method and amount of the catalyst deposited on a porous support affects its efficiency in CVD growth of CNT, the above parameters have been also optimized in this work. Alumina supported CNT,s were applied as adsorbent for removal of some organic compounds from aqueous samples. The microstructure, morphology, and chemical composition of the adsorbents were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM). Efficiency of synthesized samples for adsorption organic compounds was investigated by high performance liquid chromatography (HPLC) analysis of filtrate. This work showed that, although mesoporous alumina supported CNT can be applied as a good adsorbent for removal of trace amounts of organic compounds from drinking water efficiency of the adsorbents are extremely dependent on the porous adsorbent syntheses condition.

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Shchipunov, Yury. "Bionanocomposites: Green sustainable materials for the near future." Pure and Applied Chemistry 84, no. 12 (October 22, 2012): 2579–607. http://dx.doi.org/10.1351/pac-con-12-05-04.

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Bionanocomposites are a novel class of nanosized materials. They contain the constituent of biological origin and particles with at least one dimension in the range of 1–100 nm. There are similarities with nanocomposites but also fundamental differences in the methods of preparation, properties, functionalities, biodegradability, biocompatibility, and applications. The article includes two parts. Bionanocomposite definition and classification along with nanoparticles, biomaterials, and methods of their preparation are initially reviewed. Then, novel approaches developed by our team are presented. The first approach concerns the preparation of bionanocomposites from chitosan and nanoparticles. It is based on the regulated charging of polysaccharide by the gradual shift of solution pH. When charges appear, the biomacromolecules come into the electrostatic interactions with negatively charged nanoparticles that cause the jellification of solutions. It is also applied to form films. They have a nacre-like structure from stacked planar nanoparticles separated by aligned biomacromolecules. The second approach deals with the biomimicking mineralization of biopolymers by using a novel silica precursor. Its advantage over the current sol-gel processing is in the compatibility and regulation of processes and structure of generated silica. Another example of the mineralization is presented by titania. Syntheses are performed in anhydrous ethylene glycol. Processes and structure of bionanocomposites are regulated by water that is added in an amount to only hydrate functional groups in the carbohydrate macromolecule.

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Yilmaz, Mehmet, Maria Luisa Grilli, and Guven Turgut. "A Bibliometric Analysis of the Publications on In Doped ZnO to be a Guide for Future Studies." Metals 10, no. 5 (May 4, 2020): 598. http://dx.doi.org/10.3390/met10050598.

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This study aims to examine the studies regarding In doped ZnO published in the Web of Science database. A total of 777 articles were reached (31 March 2020). The articles were downloaded for the bibliometric analysis and collected in a file. The file was uploaded to VOSViewer programme in order to reveal the most used keywords, words in the abstracts, citation analyses, co-citation and co-authorship and countries analyses of the articles. The results showed that the most used keywords were “ZnO”, “photoluminescence”, “optical properties”, “thin films” and “doping”. These results indicate that the articles mostly focus on some characteristics of In doped ZnO thin films such as structural, optical and electrical features. When the distribution of the number of articles using the keywords by year was searched, it was found that recent articles focus mainly on synthesis of In doped ZnO film via chemical routes such as sol-gel and hydrothermal syntheses, and on ZnO-based device applications such as solar cells and gas sensors. The most used keywords were also found to be films, X-ray, glass substrate, X-ray Diffraction (XRD), spectra and layer. These results indicate that the studies mostly focus on In doped ZnO thin films as transparent conductive oxide (TCO) material used in device applications like solar cells. In this context, it was found that structural, topographical, optical, electrical and magnetic properties of In doped ZnO films were characterized in terms of defected structure or defect type, substrate temperature, film thickness and In doping content. When the distribution of these words is shown on a year-by-year basis, it is evident that more recent articles tend to focus both on efficiency and performance of In doped ZnO films as TCO in solar cells, diodes and photoluminescence applications both on nanostructures, such as nanoparticles, and nanorods for gas sensor applications. The results also indicated that Maldonado and Asomoza were the most cited authors in this field. In addition, Major, Minami and Ozgur were the most cited (co-citation) authors in this field. The most cited journals were found to be Thin Solid Films, Journal of Materials Science Materials in Electronics and Journal of Applied Physics and, more recently, Energy, Ceramics International, Applied Physics-A, Optik, Material Research Express, ACS Applied Materials and Interfaces and Optical Materials. The most co-cited journals were Applied Physics Letters, Thin Solid Films, Journal of Applied Physics, Physical Review B, and Applied Surface Science. Lastly, the countries with the highest number of documents were China, India, South Korea, USA and Japan. Consequently, it is suggested that future research needs to focus more on synthesis and characterization with different growth techniques which make In doped ZnO suitable for device applications, such as solar cells and diodes. In this context, this study may provide valuable information to researchers for future studies on the topic.

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Pénard, Anne-Laure, Thierry Gacoin, and Jean-Pierre Boilot. "Luminescent Sol-Gel Coatings Based on Nanophosphors." MRS Proceedings 988 (2006). http://dx.doi.org/10.1557/proc-988-0988-qq03-16.

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AbstractNanoparticles of lanthanide vanadate (YVO4:Ln) and phosphate (LaPO4:Ln) are obtained by simple aqueous syntheses. The nanoparticles obtained are stabilized in colloidal suspensions and deposited in sol-gel films by spin-coating using a silicate as inorganic binder. The influence of the thermal treatment on the brightness and the ability to achieve multilayer coatings are discussed.

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"Synthesis and Catalytic Activity of Spinel Ferrites: A Brief Review." Biointerface Research in Applied Chemistry 12, no. 4 (August 15, 2021): 4399–416. http://dx.doi.org/10.33263/briac124.43994416.

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The spinel ferrites have earned enormous interest worldwide because of their attractive potential applications. This review highlights different synthetic protocols of spinel ferrites such as co-precipitation, sol-gel, microemulsion, solid-state, hydrothermal, and thermal decomposition, where each method can influence the properties of ferrites. The use of ferrites in heterogeneous catalysis of various organic syntheses is discussed therein; the activity is mostly particle size-dependent. The catalytic activity of spinel ferrites towards photo-irradiated dye degradation is also studied. In the presence of H2O2 producing a Fenton-type system, ferrites have tremendous potential for dye degradation in an advanced oxidation process.

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Souza, Flávio L., Paulo R. Bueno, Ronaldo C. Faria, Elson Longo, and Edson R. Leite. "Sol-Gel Non-hydrolytic Synthesis of a Nanocomposite Electrolyte for Application in Lithium-ion Devices." MRS Proceedings 822 (2004). http://dx.doi.org/10.1557/proc-822-s3.1.

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AbstractA new nanocomposite electrolyte was synthesized using a simple non-hydrolytic sol-gel route without specific treatment of the reagents. The nanocomposite ion conductor was prepared with citric acid, tetraethyl orthosilicate and ethylene glycol, forming polyester chains. The time-consuming drying step that is a necessary part of most chemical syntheses was not required in the preparation of the present nanocomposite electrolyte of the polyelectrolyte class, because only Li+ is mobile in the polymeric chain. The effects of the concentration of Li, SiO 2 and SnO2nanoparticles were investigated in terms of Li+ ionic conductivity. Conductivity measurements as a function of the metal oxide nanocrystal content in the nanocomposite revealed a significant increase in conductivity at approximately 5 and 10 wt % of nanoparticles. The new nanocomposite conductor proved to be fully amorphous at room temperature, with a vitreous transition temperature of approximately 228K (−45°C). The material is solid and transparent, displaying an ionic conductivity of 10−4to 10−5 (O.cm)−1at room temperature presenting excellent reproducibility of all these characteristics. Cyclic voltammetry measurements indicate that the hybrid electrolyte possesses outstanding electrochemical stability.

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Chen, Yen-Tai, and Leo Chau-Kuang Liau. "Preparation of opal-based PBG crystals to develop multiple stop bands." MRS Proceedings 817 (2004). http://dx.doi.org/10.1557/proc-817-l2.6.

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AbstractOpal-based photonic band gap (PBG) crystals with multiple stop bands were prepared utilizing a sol-gel method. The fabricating procedure includes colloidal crystal syntheses, dispersion, sedimentation, coating, and thermal treatments. Each of the steps can affect the PBG properties, such as stop band locations and ranges. Different stop bands of the photonic crystals can be produced by controlling the particle sizes prepared by the colloidal crystal syntheses. A PBG crystal film with a certain stop band was formed using a particular size of the colloidal crystals coated on glass substrates. In this study, two layers of different particle sizes of PBG crystal were fabricated by different deposition conditions to demonstrate the feasibility of producing multiple stop bands. These conditions can affect the stack layers and structural regularity for forming the PBG layers. In addition, the stop band intensity of the PBG layer can be further improved by the step of thermal treatments. Results imply that multiple stop bands can be feasibly designed and produced as multiple PBG layers coating with a certain SiO2 particle size for each layer.

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Stodolny, Mikolaj, Michal Thiel, Marcin Wlodarczak, and Marek Laniecki. "Siliceous Materials for Immobilization of Photoheterotrophic Bacteria." MRS Proceedings 1326 (2011). http://dx.doi.org/10.1557/opl.2011.1394.

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ABSTRACTPreparation of transparent silica as potential carrier for photocatalysts and photosynthetic bacteria is presented. SiO2 was obtained by sol-gel techniques using tetraethyl orthosilicate as precursor. Glycol and glycerol were used as solvents. The increase of porosity of the studied materials was reached by application of soluble and commercial potato starch as a filler. Calcinations at 825 K for 6 hours removed all organic compounds. The rate of gelation was enhanced applying hydrochloric acid. Different materials were obtained in a series of syntheses with different concentrations of individual components. Transparency of the obtained materials varied between 50 and 97% (in range of λ 350 - 800 nm). Surface area varied between 300 and 400 m2/g and pore diameter was 5 – 18 nm. Samples were studied with SEM, nitrogen sorption at 77 K and UV-Vis spectroscopy. The obtained transparent materials with occluded TiO2 or CaTiO3 were tested in photocatalytic splitting of water.

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Chong, S. V., B. Ingham, and J. L. Tallon. "Two Synthetic Routes to The Formation of Tungsten Oxide Hybrid Compounds." MRS Proceedings 847 (2004). http://dx.doi.org/10.1557/proc-847-ee13.14.

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ABSTRACTThe syntheses of tungsten oxide-organic amine hybrids via homogenous and heterogeneous routes were explored and compared. In the former case, tungstic acid (H2WO4) and an appropriate amine were dissolved in ammonia solution under nitrogen atmosphere, and the product was precipitated out via evaporation of the solvent. In heterogeneous synthesis, a non-aqueous approach was employed in which H2WO4 powder was aged in a solution consisting of the amine dissolved in an appropriate organic solvent. XRD and FTIR showed that the hybrid materials obtained from the two different methods are identical. Based on these findings, we were able to prepare tungsten oxide hybrid films for the first time, by dip-coating tungstic acid films prepared from sol-gel techniques, in a non-aqueous diamine solution. The XRD spectra of these films exhibit a series of harmonic peaks, indexed as [00k ], which correspond to the Bragg peaks for the hybrid compounds. SEM shows the morphology of tungstic acid changes from the irregularly shaped platelets to a needle-like structure of the hybrids and resulted in a loosely packed coating.

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46

Govardhane, Sharayu, and Pravin Shende. "Integration of green nanotechnology with silica for corrosion inhibition." Corrosion Reviews, April 6, 2021. http://dx.doi.org/10.1515/corrrev-2020-0115.

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Abstract Silica is a chemically inert molecule with an ability of adsorption on the metal to form a layer of barrier for preventing it from the atmospheric damage. However, a larger amount of silica is required for producing the impactful anticorrosive activity, leading to toxic and carcinogenic effects in the environment, and thus limiting the applications of silica. Application of nanotechnology in the synthesis of silica nanocomposites provides, for example, the advantages of better biocompatibility, systemic stability, ineffective response towards pH changes large multifunctionality. However, uses of harmful solvent, low penetration and toxicity, remain the major concerns for silica nanoparticles. Synthesis of silica nanocomposites with green technology will be an attractive approach to offer reduction in toxicity associated with the silica, higher surface area, effective penetration, easy spreadability, better adsorption over the metal surface and also provided the controlled release of chemical agents on contact with metal surface. The present article enlightens the use of green syntheses in the formulation of silica nanocomposites for corrosion inhibition in comparison to conventional synthetic method and provides the insights of various green nanocarriers such as nanocontainers, sol-to-gel nanoparticles, metallic nanostructures and silica nanocomposites for enhancing the proficiency of corrosion inhibition.

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SHARMA, MANISH, and R. P. GAIROLA. "PERFORMANCE EVALUATION OF ZNO DOPED DIDYMIUM NANO POWDER SAMPLES." International Journal of Electronics and Electical Engineering, January 2015, 202–5. http://dx.doi.org/10.47893/ijeee.2015.1155.

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In the recent years, much attention has been focused on wide band gap semiconductors materials because of their excellent potential for blue light emitting devices, short-wavelength laser diodes and detectors in UV-blue spectral region. The wide band gap ZnO is gaining much importance for the possible application due to the capability of ultraviolet lasing at room temperature and possibilities to engineer the band gap for further use. In order to attain the potential offered by ZnO, both high-quality n-and p-type ZnO are essential. In this work we synthese the ZnO nanopowder by Sol–gel method & after that the ZnO is doped with rare earth material didymium. Didymium is a naturally occurring element with major constituent Nd and Pr and is used in many applications. The FTIR, SEM and EDX characterization techniques are applied to study the sample & it has been found that the formation of pure phase of ZnO having wurtzite hexagonal structure occurs at 1%, But at higher concentration of Di (3%, 5%) the system shows mixed phase. Moreover SEM shows that the Di doped ZnO has well ordered morphology, has low aggregation and homogeneous distribution of particle size. Note that the synthesized system is also having band gap of 3.24 eV which is comparable with the standard value.

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SHARMA, MANISH, and R. P. GAIROLA. "PERFORMANCE EVALUATION OF ZNO DOPED DIDYMIUM NANO POWDER SAMPLES." International Journal of Electronics and Electical Engineering, January 2015, 202–5. http://dx.doi.org/10.47893/ijeee.2015.1155.

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In the recent years, much attention has been focused on wide band gap semiconductors materials because of their excellent potential for blue light emitting devices, short-wavelength laser diodes and detectors in UV-blue spectral region. The wide band gap ZnO is gaining much importance for the possible application due to the capability of ultraviolet lasing at room temperature and possibilities to engineer the band gap for further use. In order to attain the potential offered by ZnO, both high-quality n-and p-type ZnO are essential. In this work we synthese the ZnO nanopowder by Sol–gel method & after that the ZnO is doped with rare earth material didymium. Didymium is a naturally occurring element with major constituent Nd and Pr and is used in many applications. The FTIR, SEM and EDX characterization techniques are applied to study the sample & it has been found that the formation of pure phase of ZnO having wurtzite hexagonal structure occurs at 1%, But at higher concentration of Di (3%, 5%) the system shows mixed phase. Moreover SEM shows that the Di doped ZnO has well ordered morphology, has low aggregation and homogeneous distribution of particle size. Note that the synthesized system is also having band gap of 3.24 eV which is comparable with the standard value.

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Alexandrov, Alexander A., Mariya N. Mayakova, Valery V. Voronov, Daria V. Pominova, Sergey V. Kuznetsov, Alexander E. Baranchikov, Vladimir K. Ivanov, Elena I. Lysakova, and Pavel P. Fedorov. "Синтез ап-конверсионных люминофоров на основе фторида кальция." Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 22, no. 1 (March 20, 2020). http://dx.doi.org/10.17308/kcmf.2020.22/2524.

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Исследование посвящено созданию люминофора на основе фторида кальция, легированного редкоземельными элементами: 5% Yb, 1% Er, с использованием методики синтеза из раствора в расплаве. В качестве растворителя использован нитрат натрия NaNO3, в качестве фторирующего агента – фторид натрия NaF. Полученные образцы охарактеризованы методами рентгенофазового анализа, рентгеноспектрального микроанализа, растровой электронной микроскопии и люминесцентной спектроскопии.В ходе работы исследовано влияние параметров синтеза на фазовый состав и морфологию частиц. Было установлено, что для формирования однофазных образцов – твёрдых растворов на основе фторида кальция – необходимо проводить синтез при температуре не ниже 400 °C, оптимальное время выдержки составило 3 ч. Установлен состав полученных образцов, он отличается от номинального и может быть записан как Ca0.88(Yb, Er)0.06Na0.06F2. Показано, что совместное вхождение натрия и ионов редкоземельных элементов повышает границы растворимости фториданатрия во фториде кальция. Энергетический выход люминесценции составил 1.21 %.По результатам работы был получен новый материал, обладающий ап-конверсионными свойствами. ЛИТЕРАТУРА Овсянкин В.В., Феофилов П.П. О механизме суммирования электронных возбуждений в акти-вированных кристаллах. Письма в ЖЭТФ. 1966;3(12):494–497. Режим доступа: http://www.jetpletters.ac.ru/ps/782/article_12079.pdf Auzel F. Compteur quantique par transfert d’energie entre deux ions de terres rares dans un tungstate mixte et dans un verre. C. R. Acad. Sci. B. 1966;262: 1016–1019. Fedorov P. P., Kuznetsov S. V., Osiko V. V. Elaboration of nanofl uorides and ceramics for optical and laser applications. In: Tressaud A., Poeppelmeier K. (eds.) Photonic and electronic properties of fl uoride materials: Progress in fl uorine science series. Amsterdam: Elsevier; 2016. p. 7–31. DOI: http://doi.org/10.1016/B978-0-12-801639-8.00002-7 Kostiv U., Rajsiglova L., Luptakova D., Pluhacek T., Vannucci L., Havlicek V., Engstova H., Jirak D., Slouf M., Makovicky P., Sedlacek R., Horak D. Biodistribution of upconversion/magnetic silica-coated NaGdF4:Yb3+/Er3+ nanoparticles in mouse models. RSC Adv. 2017;7: 45997–46006. DOI: https://doi.org/10.1039/c7ra08712h Zhao J., Zhu Y.-J., Chen F. Microwave-assisted solvothermal synthesis and upconversion luminescence of CaF2:Yb3+/Er3+ nanocrystals. J. Colloid Interface Sci. 2015;440: 39–45. DOI: http://doi.org/10.1016/j.jcis.2014.10.031 Rakov N., Maciel G. S., Xiao M. Upconversion fl uorescence and its thermometric sensitivity of Er3+: Yb3+ co-doped SrF2 powders prepared by combustion synthesis. Electron. Mater. Lett. 2014;10(5): 985–989. DOI: https://doi.org/10.1007/s13391-014-4030-9 Zhiping Z., Yingsen Y., Quamin S., Xiaotang L., Bingfu L., Yun Y. Preparation and characterization of CaF2:Yb3+, Er3+ up-conversion phosphor. Sci. Adv. Mater. 2017;9(3-4): 523–527. DOI: https://doi.org/10.1166/sam.2017.2334 Вахренёв Р. Г., Маякова М. Н., Кузнецов С. В., Рябова А. В., Поминова Д. В., Воронов В. В., Фёдоров П. П. Исследование синтеза и люминесцентных характеристик фторида кальция, легированного иттербием и эрбием, для биомедицинских приложений. Конденсированные среды и межфазные границы. 2016;18(4): 487–493. Режим доступа: https://journals.vsu.ru/kcmf/article/view/157 Yu. S., Zhi Y., Su H. Hydrothermal synthesis and upconversion properties of CaF2:Er3+/Yb3+ nanocrystals. J. Nanosci. Nanotechnol. 2014;14: 3380–3386. DOI: https://doi.org/10.1166/jnn.2014.7991 Ansaru A. A., Yadav R., Rai S. B. Physiochemical properties of greatly enhanced photoluminescence of aqueous dispersible upconversion CaF2:Yb/Ernanoparticles. Photochem. Photobiol. Sci. 2017;16: 890–896. DOI: https://doi.org/10.1039/c6pp00448b Rehmer A., Scheurell K., Kemnitz E. 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