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Baráček, Jan. "Aplikace metody sol-gel na syntézu dikalciumsilikátu a jeho tuhých roztoků." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-233387.
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The subject of this doctoral thesis was to elucidate the mechanism of reaction leading to the formation of dicalcium silicate (C2S), its solid solutions and other phosphatic calcium silicate phases using the sol-gel method of synthesis. SiO2 (Tosil A), CaO (calcium nitrate tetra-hydrate) and H3PO4 (as a source of P2O5) were used as starting materials. Series of samples with different content of P2O5 were synthesized. The characterization of Tosil A and samples was based on the following methods: DTA/TGA and EGA, XRD and SEM and EDS analy-ses. It is known, that phosphorous oxide can enter the structure of C2S and possibly form solid solutions and different phosphatic calcium silicate phases in C2S–C3P system. Depending on the P2O5 concentration in mixtures, three distinct phases are formed: larnite (2CaO•SiO2), Ca14,92(PO4)2,35(SiO4)5,65 and 5CaO•SiO2•P2O5, as detected by XRD. Local microanalysis de-monstrated the presence of calcium phosphate epicenters (C3P) containing SiO2, calcium sili-cate (C2S) zones with minimum content of P2O5 and intermediary areas of various phosphatic calcium silicates. The formation of two distinct islets of C2S and C3P is due the affinity of acid oxides (SiO2, P2O5) towards the basic one (CaO) during the sol-gel process. Then, the formation of various phosphatic calcium silicates results from the diffusion of P2O5 and SiO2 towards calcium silicate and calcium phosphate, respectively.
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Doboš, Petr. "Syntéza pěnové biokeramiky pro potenciálně lékařské aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216906.
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Cílem práce byla příprava porézních vzorků HAP pro potenciálně medicínské aplikace. HAP byl připraven metodou sol-gel a precipitační. Vzorky HAP byly podrobeny analýze FTIR, XRD, SEM. Takto připravený HAP byl napěněn pomocí houbové metody s jasně definovanými póry a pomocí polymerního a skleněného expanzelu s různou distribucí a velikostí pórů. U výsledných napěněných vzorků byla vyhodnocena mikrostruktura a povrchová analýza pomocí SEM, zjištěna porozita pomocí Hg porozimetru a sledována bioaktivita in vitro v SBF. Byly zjištěny jasně definované makro, mezo a mikro póry při různé distribuci. U houbové metody pomocí sol-gel došlo k vytvoření jasně definovaných a pravidelných pórů s monodisperzní porozitou. Dominantní velikost póru byla stanovena v rozmezí 1–5 µm. Celková porozita byla stanovena na 63,5 % s celkovým povrchem 3,048 1 m/g. Precipitační metodou s polymerním expanzelem došlo k polydisperznímu rozložení pórů s třemi hlavními fázemi v rozmezí: 50–100 µm, 5–10 µm a 0,5–1 µm. Celková porozita byla stanovena na 67,6 % s celkovým povrchem 19,090 3 m/g. Bioaktivita výsledných napěněných vzorků in vitro byla sledována po dobu 7 dnů v připraveném SBF. Při napěnění sol-gel houbovou metodou nevznikla výsledná bioaktivní vrstva. U precipitační metody napěněné pomocí polymerního expanzelu vznikla nepravidelná bioaktivní vrstva. Výsledky byly naměřeny pomocí SEM analýzy.
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Nowak, Petr. "Sledování vývoje pevnosti mezifáze sklo-keramika při její chemické modifikaci." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216346.
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Diploma thesis deals with the research of oxide interphase of ceramic composite in dependence on the amount of precursor used in sol – gel method for deposition of titanium dioxide thin layer on corundum.
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Šenk, Vít. "Keramické porézní materiály - příprava, struktura a vlastnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229407.
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The thesis targets to preparation a foam ceramics suitable for supporting, catalytic and biological applications. Theoretical part deals with methods of preparation, properties and applications of foam ceramics. Experimental part of work is focused on preparation foams by template method using polymer foam. Properties of ceramic slurry were evaluated according to discharge time of Ford cup. Foam structure is assessed using images and mechanical properties are judged by compressive tests.
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Ivan, Stijepović. "Dobijanje lantan-galata za primenu u gorivnim ćelijama." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2012. https://www.cris.uns.ac.rs/record.jsf?recordId=85671&source=NDLTD&language=en.
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U ovom radu su sintetisani prahovi na bazi lantan-galata, citratnom sol-gelmetodom i hemijskom sintezom u parnoj fazi (CVS), a njihovim presovanjemi sinterovanjem su dobijeni keramički uzorci kontrolisane mikrostrukture. Ciljdisertacije je bio dobijanje guste keramike koja bi mogla da se primeni kaojonski provodni elektrolit u gorivnim ćelijama sa čvrstim elektrolitom (SOFC),a koje bi radile na srednjim temperaturama od 500–700 °C (IT-SOFC). Po prviput su sintetisani nanoprahovi lantan-galata u gasnoj fazi i utvrđeno je da ovakodobijeni polazni prahovi, zbog svojih superiornih karakteristika omogućavajusnižavanje temperature sinterovanja za 150 °C, što je veoma povoljno kako sastanovišta dizajniranja mikrostrukture, tako i zbog uštede energije u procesuproizvodnje gorivnih ćelija. Ipak, zbog nedovoljne kontrole hemijskog sastavai stehiometrije sintetisanih prahova, što je i najveći nedostatak CVS metodedobijanja perovskitnog LaGaO3, nije bilo moguće dobiti keramiku koja bi ispunjavala zahteve za primenu u SOFC. S druge strane, citratna sol-gel metodapruža veliku kontrolu pomenutih parametara zbog čega je bila moguća sintezačitavog niza čvrstih rastvora lantan-galata. Ovom metodom su tako sintetisaničist lantan-galat (LG) i dopirani prahovi kod kojih je deo lantana supstituisanstroncijumom, a deo galijuma magnezijumom: La0,85Sr0,15Ga0,85Mg0,15O3-La1-xSrxGa0,8Mg0,2O3-, gde je x = 0,10, 0,15 ili 0,20 (LSGM). Svi ovako sintetisaniprahovi su zahtevali naknadnu kalcinaciju na 900 °C, ali su potrebnegustine (>95% teorijske gustine) postignute sinterovanjem na temperaturiod 1450 °C već nakon 2 h, što je izuzetno kratko imajući u vidu literaturnepodatke. Takođe, sinterovani uzorci su po faznom sastavu bili čista LSGMkeramika, a impedansna merenja su pokazala da je najveću provodljivost imaouzorak La0,85Sr0,15Ga0,8Mg0,2O3-. Ovaj sastav je dalje korišćen u cilju proveremogućnosti za dodatno povećanje provodljivosti te su pripremljeni i uzorci kod kojih je izvršena parcijalna supstitucija magnezijuma sa niklom ili kobaltom:La0,85Sr0,15Ga0,8Mg0,2-yMyO3-, gde je M = Ni ili Co, a y = 0,03 ili 0,05 (LSGMN iLSGMC). Pokazano je da dodatak male količine prelaznih metala značajno utičena mehanizam provođenja, ali da je na višim temperaturama jonska provodljivosti dalje dominantna. Konstatovano je da se dodavanjem male količine Ni ili Co uLSGM mogu dobiti materijali koji bi služili kao elektroliti u IT-SOFC, pri čemu jepotencijal nikla kao dopanta nešto veći nego kobalta.Powders based on lanthanum-gallate have been synthesised in this work by using citrate sol-gel method in the liquid phase and by chemical vapour synthesis (CVS). As-synthesised powders were calcined, pressed and finally sintered in order to produce ceramic samples with controlled microstructure. The main goal of this dissertation has been obtaining of dense ceramics for application in ion conducting electrolyte for solid oxide fuel cells working at 500–700 °C (IT-SOFC). Lanthanum-gallate nanopowders have been synthesised in the gas phase for the first time and it has been determined that these starting powders posses superior properties which could lower down the sintering temperature for about 150 °C. This is very significant considering microstructure design, but also high energy consumption during the manufacturing process of fuel cells. However, it has not been possible to obtain ceramics with exact properties needed for SOFC application using CVS due to the lack of control of chemical composition and stoichiometry of the as-synthesised powders, which are the main drawbacks of this method. On the other hand, citrate sol-gel method offered a possibility to precisely control aforementioned parameters which enabled synthesis of a whole range of lanthanum-gallate sollid solutions. So, pure perovskite lanthanum-gallate (LG) has been synthesised by using this liquid phase method, but also doped powders where part of lanthanum and gallium was supstituted with strontium and magnesium, respectively: La0,85Sr0,15Ga0,85Mg0,15O3- and La1-xSrxGa0,8Mg0,2O3-, where x = 0.10, 0.15 or 0.20 (LSGM). Calcination at 900 °C was necessary step during the processing of these sol-gel powders but the sintering time at 1450 °C was only 2 h which is quite short in comparison with available literature data. Additionaly, the sintered samples were phase pure LSGM ceramics and impedance measurement showed that the highest conductivity had sample La0,85Sr0,15Ga0,8Mg0,2O3-. Accordingly, this composition has been used to check the possibility of further improvement of conductivity. A set of new samples has been prepared where one part of magnesium has been substituted with nickel or cobalt: La0,85Sr0,15Ga0,8Mg0,2-yMyO3-, where M = Ni or Co and y = 0.03 or 0.05 (LSGMN i LSGMC). It has been shown that addition of small amount of transition metals significantly influences conduction mechanism, but at higher temperatures the ionic conductivity is still dominant. It has been found that electrolyte materials for IT-SOFCs could be obtained by incorporation of small quantities of Ni or Co into LSGM and that nickel is more promissing for this purpose than cobalt.
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Marzini, Michael. "Automatisierung und Optimierung des Sol-Gel-Prozesses." [S.l. : s.n.], 2006.
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Sparks, Jeffery Scott. "Production of mullite fibers by the sol-gel method." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/9135.
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Čižauskaitė, Sigutė. "Sol-gel synthesis of perovskite structure aluminates and cobaltates." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20091202_112230-17664.
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In the present thesis the reported results let us to conclude that the developed aqueous sol–gel procedure could be successfully used for the low-temperature synthesis of monophasic perovskite gadolinium aluminate ceramics. It was also demonstrated that the selection of raw materials for the sol–gel processing should be done with care. Monophasic perovskite structure gadolinium aluminate GdAlO3 has been synthesized by sol gel synthesis method at 1000 oC, using gadolinium oxide as gadolinium raw material and 1.2 ethanediol, natural tartaric acid, citric acid or mixture of citric acid and ethanolamine as complexing agent. According to the XRD results, the Gd2O3 instead of Gd(NO3)36H2O preferably should be used as starting material for the preparation of GdAlO3. Monophasic perovskite structure strontium substituted gadolinium aluminate Gd0.90Sr0.10AlO3– was synthesized by the same sol gel synthesis method at 1000 oC, using gadolinium oxide as gadolinium raw material, strontium nitrate as strontium ion source and EDTA as complexing agent. It was proved that better gadolinium ion source is gadolinium oxide than gadolinium nitate hexahydrate, better complexing agent – EDTA than natural tartaric acid in the synthesis of GdAlO3 and strontium substituted Gd1–xSrxAlO3– (x = 0.10, 0.25, 0.50, 0.75) samples. According to the XRD results, increasing amount of strontium reduces amount of peaks of perovskite structure gadolinium aluminate. Besides, 800 ºC temperature is too low for the... [to full text]Šiame darbe vienfazis perovskito struktūros gadolinio aliuminatas GdAlO3 zolių-gelių metodu buvo gautas 1000 oC temperatūroje, gadolinio jonų šaltiniu naudojant Gd2O3, kompleksus sudarančiu reagentu – 1,2 etandiolį, natūralią vyno rūgštį, citrinų rūgštį arba citrinų rūgšties ir etanolamino mišinį. Sintetinant GdAlO3, gautų tyrimų rezultatai parodė, kaip yra svarbu zolių gelių procese pasirinkti tinkamas pradines medžiagas bei kompleksus su metalais sudarančius reagentus: gadolinio jonų šaltiniu naudojant Gd2O3 buvo gauti geresni rezultatai nei naudojant Gd(NO3)3•6H2O, vienfazis GdAlO3 gali būti sėkmingai susintetintas kompleksus sudarančiu reagentu naudojant tiek natūralią vyno rūgštį, tiek 1,2 etandiolį, tiek citrinų rūgštį, tiek citrinų rūgšties ir etanolamino mišinį. Nustatyta, kad sintetinant stronciu pakeistus gadolinio aliuminatus Gd1–xSrxAlO3– (x = 0,10, 0,25, 0,50, 0,75), tinkamesnis gadolinio jonų šaltinis yra gadolinio oksidas nei gadolinio nitratas heksahidratas, kompleksus sudarantis reagentas – EDTA nei natūrali vyno rūgštis. Vienfazis perovskito struktūros stronciu pakeistas gadolinio aliuminatas Gd0,90Sr0,10AlO3– buvo susintetintas zolių-gelių metodu 1000 oC temperatūroje, gadolinio jonų šaltiniu naudojant Gd2O3, stroncio jonų šaltiniu – Sr(NO3)2, kompleksus sudarančiu reagentu – EDTA. Be to, 800 ºC iškaitinimo temperatūra yra per maža šiems junginiams sintetinti. Pirmą kartą pasiūlytas vandeninis zolių gelių metodas lantano ir gadolinio kobaltatams... [toliau žr. visą tekstą]
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McAughey, Kevin. "Fabrication of high temperature piezoelectric ceramics by sol gel method." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/55918/.
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This research covers the fabrication of piezoelectric ceramics using a sol gel method. Commercial high temperature transducers are typically fabricated by a milled oxide method. The sol gel method presented here produced purer samples that can be prepared at lower temperatures than conventional milled oxide preparations. The performance of the samples as piezoelectric transducers was also investigated, with the samples produced by sol gel method exceeding the piezoelectric response of the commercial samples.
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Yang, Lan Vahala Kerry. "Fabrication and characterization of microlasers by the sol-gel method /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-06032005-115306.
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Dubnikova, Natalija. "Sol-gel synthesis and characterization of lanthanide aluminium garnets." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20111227_092034-78155.
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The development and application of advanced materials is a very important task of today's information society. Garnet crystal structure compounds because of their specific physical and chemical properties are widely used in information technology, manufacturing of solid-state lasers and optical equipments, medical equipments and many other areas. Therefore, these materials because of their unique properties and characteristics are of high interest so far.
For the first time Ce-Al-O, Pr-Al-O, Nd-Al-O, Tb-Al-O, Dy-Al-O, Ho-Al-O, Er-Al-O, Tm-Al-O, Yb-Al-O, Lu-Al-O, Y(Nd)-Al-O and Y(Sm)-Al-O acetate-nitrate-glycolate gels have been synthesized using environmentally friendly, economical and simple aqueous sol-gel method. They were used as starting materials for the synthesis of appropriate lanthanide aluminium garnets. The results of X-ray difraction analysis have indicated that single-phase terbium aluminium garnet (Tb3Al5O12), dysprosium aluminium garnet (Dy3Al5O12), holmium aluminium garnet (Ho3Al5O12), erbium aluminium garnet (Er3Al5O12), thulium aluminium garnet (Tm3Al5O12), ytterbium aluminium garnet (Yb3Al5O12) and lutetium aluminium garnet (Lu3Al5O12) have been synthesized by annealing Tb-Al-O, Dy-Al-O, Ho-Al-O, Er-Al-O, Tm-Al-O, Yb-Al-O and Lu-Al-O precursor gels for 10 hours at 1000 °C, respectively. For the first time these garnet structure compounds were synthesized using sol-gel method. Moreover, these lanthanide aluminium garnets were synthesized at relatively low... [to full text]Pažangių medžiagų bei technologijų kūrimas ir taikymas - tai labai svarbus šiandieninės informacinės visuomenės uždavinys. Granato kristalinės struktūros medžiagos, pasižymėdamos ypatingomis fizikinėmis bei cheminėmis savybėmis, yra plačiai naudojamos informacinių technologijų, kietafazių lazerių, optikos įrenginių gamybose, medicinos įrangose, bei daugelyje kitų sričių. Todėl jos dėl savo unikalių savybių ir plačiai tebetyrinėjamos iki šiol. Šiame darbe pirmą kartą buvo susintetinti Ce-Al-O, Pr-Al-O, Nd-Al-O, Tb-Al-O, Dy-Al-O, Ho-Al-O, Er-Al-O, Tm-Al-O, Yb-Al-O, Lu-Al-O, Y(Nd)-Al-O ir Y(Sm)-Al-O acetatiniai-nitratiniai-glikoliatiniai geliai zolių-gelių metodu vandeniniuose tirpaluose. Jie buvo panaudoti pradinėmis medžiagomis atitinkamų lantanoidų aliuminio granatų sintezei. Vienfaziai terbio aliuminio granatas (Tb3Al5O12), disprozio aliuminio granatas (Dy3Al5O12), holmio aliuminio granatas (Ho3Al5O12), erbio aliuminio granatas (Er3Al5O12), tulio aliuminio granatas (Tm3Al5O12), iterbio aliuminio granatas (Yb3Al5O12) ir liutecio aliuminio granatas (Lu3Al5O12) buvo gauti, terbio jonų šaltiniu naudojant terbio oksidą, disprozio – disprozio oksidą, holmio – holmio oksidą, erbio – erbio oksidą, tulio – tulio oksidą, iterbio – iterbio oksidą, lutecio – liutecio oksidą, kompleksus sudarančiu reagentu 1,2-etandiolį. Tyrimų rezultatai parodė, kad šių lantanoidų aliuminio granatai gauti santykinai žemoje temperatūroje (1000°C). Zolių-gelių metodu sintetinant cerio aliuminio granatą... [toliau žr. visą tekstą]
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Cesquini, Renato Giovani. ""Sintese de aluminas utilizando-se o metodo sol-gel : caracterização e aplicação em reações de epoxidação"." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249504.
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Orientador: Ulf Friedrich SchuchardtDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Mestrado
Quimica Inorganica
Mestre em Química
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Eguiluz, Katlin Ivon Barrios. "Desenvolvimento de catalisadores preparados pelo método sol-gel para a oxidação de metanol." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-11092008-155151/.
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Este trabalho descreve o desenvolvimento e caracterização de novos materiais catalíticos para a oxidação de metanol em aplicações em células a combustível de metanol direto. Os materiais foram preparados utilizando o método sol-gel pela incorporação de diversas quantidades de metais, tais como: Ru, Ir, Ce, Mo e Pb sobre amostras de pó de Pt/C da E-Tek (10% Pt). Na maioria dos casos, o compósito resultante estava formado pelos referidos óxidos metálicos como observado nas medidas de caracterização física. Os sistemas estudados incluíram as seguintes misturas binárias: (Pt0,50-(RuO2)0,50/C, Pt0,50-(IrOx)0,50/C, Pt0,50-(CeO,sub>2)0,50/C, (PtOx)0,50-(PbOx)0,50/C, Pt0,50-(Môo3)0,50/C) e as misturas ternárias: (Pt0,25(RuO2-IrOx)0,75/C, Pt0,50 (RuO2-IrOx)0,50/C, Pt0,75(RuO2-IrOx)0,25/C, Pt0,25(RuO2-CeO2)0,75/C, Pt0,50 (RuO2-CeO2)0,50/C, Pt0,75(RuO2-CeO2)0,25/C, (PtOx)0,25(RuO2- PbOx)0,75/C, (PtOx)0,50 (RuO2-PbOx)0,50/C, (PtOx)0,75(RuO2-PbOx)0,25/C, Pt0,25(RuO2- Môo3)0,75/C, Pt0,50(RuO2-MoO3)0,50/C e Pt0,75(RuO2-MoO3)0,25/C). Medidas de difratometria de raios-X, mostraram que todos os metais incorporados às amostras de Pt/C sintetizam-se como óxidos (RuO2, IrO2, Ir2O3, CeO2, Pb3O4 e MoO3), enquanto que a platina manteve-se como Pt metálica com exceção nos compósitos contendo chumbo, nos quais na sua composição final mostraram Pt, assim como, PtO e PtO2. Os compósitos preparados pelo método sol-gel foram de tamanho nanométrico (2,8- 3,5 nm) como observado por microscopia eletrônica de transmissão assim como por difração de raios-X, enquanto que, medidas de energia dispersiva de raios-X mostraram que os compostos apresentam composições próximas aos valores usados na preparação experimental. A oxidação de metanol foi estudada em todos os compósitos por voltametria cíclica seguida pelas curvas de polarização em estado quase-estacionário com os correspondentes diagramas de Tafel e finalmente pelos testes cronoamperométricos com análise por cromatografia dos principais produtos na solução. x Os valores do coeficiente angular obtidos nos diagramas de Tafel (b) são um indicativo que a etapa determinante da velocidade da reação (rds) de eletro-oxidação de metanol sobre os catalisadores contendo Ir é a quebra de uma das ligações C-H na molécula de CH3OH com a transferência do primeiro elétron (b = 120 mV dec-1). Entretanto, para os outros catalisadores estudados os valores de (b estão em torno de 90 mV dec-1, indicando que a rds nesses casos pode ser à remoção oxidativa do COads pelos intermediários adsorvidos provenientes da oxidação da molécula de água (R-OH.). Por outro lado, análises cromatográficos dos produtos formados em solução durante os testes cronoamperométricos mostraram que o compósito Pt0,25(RuO2-IrOx)0,75/C apresentou o melhor desempenho catalítico para oxidação de metanol. Isto devido a que, sobre este catalisador, não foi observado acúmulo de formaldeído em quanto que o ácido fórmico remanescente foi menor do que o observado sobre os outros catalisadores estudados, usando cargas elétricas equivalentes. Isto é um forte indicativo de que a oxidação de metanol em este material é eficiente, oxidando também moléculas de formaldeído e ácido fórmico até CO2 sem a formação de intermediários solúveis na solução. Portanto, este estudo mostra claramente que os melhores catalisadores para a oxidação de metanol são: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50(RuO2-IrOx)0,50/C e Pt0,75(RuO2-IrOx)0,25/C, confirmando que a combinação de Pt, Ru e Ir é promissora para esta aplicação.The preparation and the physical and electrochemical characterization of several binary and tertnary new composite catalytic materials for the direct oxidation of methanol in fuel cell systems are described here. The materials were prepared using the sol-gel method for the incorporation of variable amounts of metals such as Ru, Ir, Ce, Mo and Pb onto commercial samples of Pt/C powder from E-Tek (10% Pt). In most cases, the resulting composite was formed by the corresponding metal oxides as indicated by the subsequent physical characterization measurements. The systems studied included the following binary mixtures: Pt0,50-(RuO2)0,50/C, Pt0,50-(IrOx)0,50/C, Pt0,50-(CeO,sub>2)0,50/C, (PtOx)0,50-(PbOx)0,50/C, Pt0,50-(Môo3)0,50/C and the ternary ones: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50 (RuO2-IrOx)0,50/C, Pt0,75(RuO2-IrOx)0,25/C, Pt0,25(RuO2-CeO2)0,75/C, Pt0,50 (RuO2-CeO2)0,50/C, Pt0,75(RuO2-CeO2)0,25/C, (PtOx)0,25(RuO2- PbOx)0,75/C, (PtOx)0,50 (RuO2-PbOx)0,50/C, (PtOx)0,75(RuO2-PbOx)0,25/C, Pt0,25(RuO2- Môo3)0,75/C, Pt0,50(RuO2-MoO3)0,50/C and Pt0,75(RuO2-MoO3)0,25/C X-ray diffraction measurements revealed that all metals incorporated to the Pt/C samples appeared as oxides (e.g. RuO2, IrO2, Ir2O3, CeO2, Pb3O4 e MoO3) while platinum remained metallic except for the composites containing lead where the final composition showed metallic Pt as well as PtO and PtO2. The sol-gel prepared composites were nanometric in size (2.8 - 3.5 nm) as shown by electronic transmission microscopy as well as by X-ray diffraction while energy dispersive Xray measurements indicated that the composites have compositions values very close to those of the experimental preparation. Methanol oxidation was studied on all composites by cyclic voltammetry followed by quasi steady-state polarization curves with the corresponding Tafel plots and, finally, by chronoamperometric tests with analyses of the main products in solution by chromatography. xii The measured values of the Tafel coefficient (b) are an indicative that the ratedetermining- step (rds) for methanol oxidation on catalysts containing Ir is the rupture of one of the C-H bonds in the CH3OH molecule with the transference of one electron (CH3OH = ~120 mV dec-1). For the other composites studied the b values are around 90 mV dec-1 indicating that the rds in those cases could be the oxidative removal of COads by the adsorbed intermediates of the water molecule oxidation (R-OH.). On the other hand, the chromatographic analyses of the products formed in solution during the chronoamperometric tests seem to point out that the Pt0,25(RuO2-IrOx)0,75/C composite is the one with the best catalytic performance for methanol oxidation. This is because for that material an accumulation of formaldehyde was not observed while the remnant formic acid was lower than for the other tested composites using equivalent electric charges. This is a strong indicative that the oxidation of methanol on that material efficiently also oxidizes the formaldehyde and the formic acid molecules to CO2 not leaving soluble intermediates in solution. Therefore, the present studies clearly show that the best catalysts for methanol oxidation are: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50(RuO2-IrOx)0,50/C e Pt0,75(RuO2-IrOx)0,25/C, thus confirming that a proper combination of Pt, Ru and Ir is very promising for such application.
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Pinheiro, Eduardo Antonio. "Uso de metodo sol-gel e de coprecipitação na preparação de oxidos metalicos." [s.n.], 1992. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249776.
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Orientador : Fernando GalembeckTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Doutorado
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D’Agostino, Simone <1981>. "Preparation of new crystal forms via photochemical, mechanochemical and sol-gel methods." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4650/.
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This work of thesis involves various aspects of crystal engineering. Chapter 1 focuses on crystals containing crown ether complexes. Aspects such as the possibility of preparing these materials by non-solution methods, i.e. by direct reaction of the solid components, thermal behavior and also isomorphism and interconversion between hydrates are taken into account.
In chapter 2 a study is presented aimed to understanding the relationship between hydrogen bonding capability and shape of the building blocks chosen to construct crystals. The focus is on the control exerted by shape on the organization of sandwich cations such as cobalticinium, decamethylcobalticinium and bisbenzenchromium(I) and on the aggregation of monoanions all containing carboxylic and carboxylate groups, into 0-D, 1-D, 2-D and 3-D networks.
Reactions conducted in multi-component molecular assemblies or co-crystals have been recognized as a way to control reactivity in the solid state. The [2+2] photodimerization of olefins is a successful demonstration of how templated solid state synthesis can efficiently synthesize unique materials with remarkable stereoselectivity and under environment-friendly conditions. A demonstration of this synthetic strategy is given in chapter 3.
The combination of various types of intermolecular linkages, leading to formation of high order aggregation and crystalline materials or to a random aggregation resulting in an amorphous precipitate, may not go to completeness. In such rare cases an aggregation process intermediate between crystalline and amorphous materials is observed, resulting in the formation of a gel, i.e. a viscoelastic solid-like or liquid-like material.
In chapter 4 design of new Low Molecular Weight Gelators is presented. Aspects such as the relationships between molecular structure, crystal packing and gelation properties and the application of this kind of gels as a medium for crystal growth of organic molecules, such as APIs, are also discussed.
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Pulmannová, Dorota. "Příprava a charakterizace substituovaných Y ferritů ve formě keramik a tenkých vrstev." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-354144.
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Title: Preparation and characterization of substituted Y ferrites in the form of ceramics and thin films Author: Dorota Pulmannová Department: Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague Supervisor: RNDr. Daniel Nižňanský, Ph.D. Consultant: Ing. Josef Buršík, CSc. Abstract: In this work we describe a preparation and characterization of a hexagonal ferrite series with composition BaSrCoZnXFe11O22 where X=Fe, Al, Ga, In and Sc. We have prepared these ferrites in the powder and ceramic form using the citrate synthesis and in the thin film form using the chemical solution deposition method. Using the powder neutron diffraction we have found that the sample containing only Fe has collinear magnetic structure that belongs to the C2/m or C2'/m' group. Magnetic structure of the samples substituted with In and Sc is similar, but the magnetic moments of the 18hVI site atoms are not aligned parallely with the other moments. Magnetic structure of Ga-substituted sample is different, it is modulated with a propagation vector k ≈ (0, 0, 3/4). Propagation vector of the Al-substituted ferrite is k ≈ (0, 0, 3/2). Substituting elements show strong preferences for the cation sites. Al and Ga prefer the 3bVI site, Zn prefers the tetrahedral 6cIV and In and Sc prefer the 6cVI site. Room...
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Ting, Wei-He, and 丁維和. "Prepare PZT powder by sol-gel method." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/42822461982389578388.
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Tsai, Cheng Che, and 蔡政哲. "Synthesis optical material with sol-gel methad." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/75828428742363705662.
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Tseng, Shin-Yi, and 曾心誼. "Ta2O5 thin films prepared by Sol-Gel method." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/35261148218995324385.
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碩士國立交通大學
材料科學與工程研究所
85
In this work we studied the preparation, structure and properties of Ta2O5 films grown by sol-gel method. The specimems were prepared byspin-coating the starting solution containing Ta(OC2H5)5 onto Si wafersfollowed by various heat treatments. X-ray and AES analyese indicted atthe film has [O]/ [Ta] ratio rather close to exact stoichiometry. The films annealed at 400℃for 4hrs exhibited the highest dielectric constant (24.27) and the best breakdown voltage (1.23MV/cm). However, as revealed by TEM, SEM and AFM characterizations, the Ta2O5 films prepared by sol-gelmethod contained many micro- defects and voids which severely restricted their electrical performance. Recrystallization during further annealsinduced even more defects in Ta2O5 films, which showed no benefication of both structure and electrical properties of the films.
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Huang, Shi-Xiang, and 黃詩翔. "Preparation for V2O5-SiO2 by Sol-Gel Method." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/82040213402673674342.
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Hwung, Shy-Shyang, and 黃詩翔. "Preparation for V2O5-SiO2 by Sol-Gel Method." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/43847380398273314356.
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Pai, Chia-Wei, and 白家維. "Mesoporous Leucite Porcelain Synthesized by Sol-Gel Method." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/228v93.
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碩士國立臺北科技大學
材料科學與工程研究所
97
The purpose of this study was tried to fabricate the leucite porcelain with ordered mesoporous structure. We have four topics in this plan to discuss. A study amount on the basis of the interactions between inorganic-organic to form meso-structured composites.The reaction temperature is relatively order of mesostructure. The pore structures of mesoporous materials depend on the temperature changing and pore condition of mesoporous materials depend on the pH value of micells formation. The results shown the temperature of calcination over 900℃ leucite crystal was obtained. The triblock copolymer surfactant (P123) was employed as the structure agents for synthesizing the mesopore leucite at room temperature. According to the isothermal nitrogen adsorption-desorption curve and the Barrett- Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) theories, the results shown that the mesoporous structure with the pore size of 7~8 nm. The concentration of the surfactant low micelle formation is difficult to great shape. P123 was 0.38 mol ratio to obtaine the best amount and order of mesopore. Pores were break down when the temperature of calcination were over 650℃.Decreasing surfactant mol ratio was helpful for order mesostructure formation when aging at 60℃.But it could be opposite when increasing surfactant. Then, poer size and the BET value were decreased with the increasing pH value. These results were confirmed by TEM and reveal a highly ordered 2D-hexagonal arrangement of one-dimensional channel with a symmetry p6mm space group.
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Wang, Chang-Long, and 王敬龍. "Preparation of ITO film by sol-gel method." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/29054700599327044952.
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Lyu, Chun Cheng, and 呂俊成. "Synthesis of Mesoporous Ta2O5 by Sol-gel Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08432998939674878733.
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碩士國立屏東科技大學
機械工程系所
98
Ta2O5 finds its promising application in catalysis, solid oxides fuel cells and sensors. After absorbing the ultraviolet ray, it has the light catalyst effect and further resulting in hydrolysis to producing the hydrogen energy. Many applications would benefit from the enhancement of the chemical reaction of Ta2O5. Mesostructured material due to its tailored pore structures and high surface area, thus improving the effectiveness of the material has attracted increasing attentions in recent years. Mesoporous Ta2O5 are obtained by the sol-gel process with the block copolymer as a natural template and Ni(NO3)2．6H2O as an inorganic precursor. In this work, we changed the precursors, with different ratios of block copolymer additives, to study their effect on the crystallinity, as well as the effect on the structure of Ta2O5 at various calcining temperatures. XRD, TEM, SAXS and N2 absorption-desorption isotherms were used to characterize the structure and the specific surface area of the samples.Our experiments demonstrated that Mesoporous Ta2O5 obtained by using 1.0~2.0g block copolymer with a temperature 700 ºC , expressed the orthorhombic structure . It had a surface area of 51.54 m2/g , and the average pore diameter was 49.19 Å.When increases block copolymer 1.0 g and temperature 600 ºC, because of the TEM analysis may observe the insect shape the hole structure，by N2 absorption-desorption isotherms May know the powder. Adding 2 wt％ Ni(NO3)2．6H2O with the calcination temperature of 500 ℃, the mesoporous Ta2O5 had a much higher specific surface area of 94.97 m2/g, and an average pore size of 44.20 Å.Increasing to 6 wt% Ni(NO3)2．6H2O with 600 ℃ the mesoporous Ta2O5 expressed the crystallization phase, which indicated that the appropriate increase of Ni(NO3)2．6H2O largely affects the crystallizing point.
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HSU, WEN-CHIEH, and 徐文傑. "Synthesis of Mesoporous Al2O3 by Sol-Gel Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/15849907978799946462.
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碩士國立屏東科技大學
機械工程系所
98
Al2O3 is an important element industrial chemistry that has applied widely as adsorbents, ceramics ,abrasives, catalysts and catalyst supports, ext. Especially organized mesoporous alumina has a high potential on commercial applications in catalysis. Mesostructured alumina compares with general nanometer materials which has the character of tailor pore structures and high surface areas .Thus ,it has become an important research study in recent years. First, in this study,organized mesoporous alumina is synthesized by the sol-gel process method with nitrate alumina as source of alumina, organic surfactant triblock copolymer F68 as template. Second, the influence of various conditions on the structure of organized mesoporous alumina was discussed. Finally, by XRD, BET, SAXS, SEM, TEM and N2 adsorption-desorption isotherms, we analyzed the microstructure and specific surface area. The results showed that using triblock copolymer as the template and calcined above 800 ℃, mesoporous γ-Al2O3 with the cubic structure was obtained by XRD analysis. Observing the TEM pattern of the mesoporous Al2O3 calcined at 500 ℃, we found it should be the structure of wormhole-like mesoporous Al2O3,and the mesoporous structure was decidedly. According to the nitrogen adsorption/desorption isotherms of the mesoporous Al2O3 ,the shape of type Ⅳ lagged curve was observed. It also represented the adduct having mesoporous structure. Analyzing from BET and BJH, we found the temperature at 500~800 ℃ was closely overlap when adding Ce(NO3)3 • 6H2O in the experiment. It can keep the N2 adsorption-desorption isotherms curves stability. That is to say adding its heat temperature stability. When adding Ce(NO3)3 to 1.5 g and calcined at 500 ℃, the mesoporous Al2O3 had a specific surface area of 87.69 m2/g and the average pore size of 147.7 Å. However, as the calcining temperature increasing to 800 ℃, the specific surface area of mesoporous Al2O3 became to 71.1 m2/g and the pore volume was 140.01 Å. Keywords : sol-gel method, mesoporous materials, surfactants,template
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Ren, Chi Chun, and 任啟中. "Use the Sol-Gel Method to Prepare Zirconia." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/09027812798387833577.
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Chen, Hong Ming, and 陳鴻銘. "Synthesis of Mesoporous Titania by Sol-gel Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/68891272606010457793.
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碩士國立屏東科技大學
機械工程系所
95
Recently, mesostructured materials with high surface areas and large pore sizes have attracted much attention because of their potential applications in the areas of adsorption and catalysis. In this study, mesoporous TiO2 was prepared by sol-gel process and the synthesis was accomplished by using block copolymer as the template, and TiCl4 as the inorganic precursor. TGA, XRD, TEM and N2 adsorption-desorption isotherms were used to characterize the microstructure of the samples. Using F108 block copolymer as the template, mesoporous TiO2 with the anatase structure was obtained at 300~400°C. Mesoporous TiO2 exhibits a high BET surface area of 284.75 m2/g, and an average pore size of 4.8 nm for 300℃ calcination and using 1.5 g block copolymer. The addition of block copolymer can affect the structure of mesoporous. The addition of block copolymer increased from 0.1 to 1.5 g, and the specific surface area increased from 63.14 to 229.17 m2/g, but the average pore size decreased from 11.04 to 5.0 nm after calcined at 350°C for 5hrs. The water content in the reaction system is believed to determine the crystal structure formation. Mesoporous TiO2 with pure anatase have been successfully synthesized with pure alcohol, but bicrystalline (anatase and rutile structures) were obtained when replaced with H2O. The results showed that mesoporous TiO2 prepared with 25 % replacement of H2O and calcined at 300°C for 5 hrs exhibits a high surface area of 565.4 m2/g and an average pore size of 5.2 nm.
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Huang, Jian-wei, and 黃健瑋. "Study of Neodymium Doped ZnO by Sol-Gel Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/87847394467618590140.
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碩士國立臺灣科技大學
電子工程系
95
We report the growth and characterization of neodymium doped ZnO prepared by sol-gel method. As-grown and annealed sample were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman Scattering Spectroscopy (Raman), and Photoluminescence (PL). PL study of Nd:ZnO by using a He-Cd laser at 325 nm shows bandgap emission at 377 nm and defect related luminescence. Nd:ZnO also shows luminescence of Nd3+ near 890 nm by using He-Cd laser. The infrared emission is due to the electrons transition from 4F3/2 to 4I9/2 of Nd3+. Nd:ZnO annealed at 400℃ shows stronger luminescence of Nd3+. The infrared emission of Nd3+ changed its intensity with variation of annealing temperature. XRD shows Nd2O3 appears when Nd:ZnO annealed at high temperature and it will influence luminescence of Nd3+.
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許鴻昇. "Optical wave-guide prepared by ZrO2 sol-gel method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/17139059522564888612.
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碩士明新科技大學
電子工程研究所
95
Abstract This project is to study SiO2/ZrO2/SiO2/Si wave guide deposited on Si(100) prepared by the sol–gel method. ZrO2 is an inexpensive , and wide band gap with high luminous transmittance, high refraction index, high K and hardness. ZrO2 thin films can be deposited by a number of techniques such as RF sputtering, chemical vapor deposition (CVD), pulsed laser deposition, and sol–gel method. The sol-gel process has the advantage of large area deposition, in addition to its low cost and convenience process control. Hence the method is suitable for frontier researches. ZrO2 films can be prepared by the sol–gel process under different recipe and annealing temperature . In this work, the effect of annealing temperature and recipe of the sol-gel process on structural and optical properties of the sol-gel derived ZnO thin films can be investigated.XRD, SEM, ellipsometer, and photoluminescence measurements investigate structural and optical properties.
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HUANG, JIAN-QING, and 黃建清. "Syntheses of silica glasses by the sol-gel method." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/76493347795822951267.
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ZHANG, GE-YING, and 張格滎. "CdS doped silica glasses prepared by sol-gel method." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/17229598545026405862.
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Hsu, HueiTing, and 許惠婷. "Preparation of Sol-Gel Antireflection Coating by Templating Method." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/77570078693443982034.
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碩士國立臺灣大學
化學工程學研究所
90
Antireflection coatings can reduce the intensity of light-reflection (and increase the transmittance) and increase the quality of optical lens system. Reflectance can be minimized at normal incidence, when refractive index and thickness satisfy two conditions: (i) n=√(n0nS) where n、 n0 and ns are refractive indices of the film, air and substrate, respectively. (ii) Film thickness (t) must be 1/4 of a reference wavelength in the film for the reflected light to interfere destructively. That is t=λ/(4n) . Therefore, when λ0 ~510nm is chosen and glass (ns=1.52) is used as a substrate, the optimum refractive index and thickness of antireflection film can be calculated as n~1.23 and t~100nm, respectively. In this presentation, a sol-gel derived porous SiO2 coating by surfactant templating method is introduced. Because the refractive index of a dense SiO2 film is also 1.52, the desired film refractive index can be reduced by adjusting the porosity of the SiO2 film. The spin coating process was used to deposit SiO2 thin films on glasses. The pore size and the pore volume of the film were controlled by the volume of the template (i.e. Tween 80). It was found in this research that the transmittance was increased from 92% to 99.6% by a single-layer porous SiO2 antireflection coating on both sides of the glass pane at ~600nm, over the range 540~740nm wavelength, the transmittance ＞99%. And the transmittance was increased from 92% to 99.4% by a double-layer porous SiO2 antireflection coating on both sides of the glass pane at ~713nm, over the range 570~800nm wavelength, the transmittance ＞99%.
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Chou, Chin-Sheng, and 周金生. "PTC thermistor of nano-titanate by Sol-gel method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/42772308070744168176.
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碩士國立高雄應用科技大學
化學工程與材料工程系
98
The high quality nanoscale barium titanate (BaTiO3) and strontium titanate (SrTiO3) powders were made by Sol-gel method, and then these powders were put into the manufacture production process to fabricate brand new PTC thermistor. In order to make sure the solution can be dissolved clearly and homogeneous, the starting materials of barium acetate, strontium acetate and Titanium(IV) isopropoxide etc. were used to keep all the mixing process to be controlled under solution state. The distributions of elements for sintered ceramic produced by Sol-gel method are more homogenous than by Solid-state method. Dissolution and reaction process were achieved by adding water, 2,4 - pentanedione and other solvents. Too much solvent will reduce the formation of crystalline barium titanium. The fewer amount of the solvents were used for Sol-gel process according to the mixing condition. The better volume ratio of solvent is that water：2,4 – pentanedione：ethylene glycol monomethyl ether：ethanol = 1：0.11：0.19：0.19。 The temperature of calcination required is 900℃at least for the trial run by X-ray diffraction analysis. But the temperature of calcination required is raised to 1200℃ at least for the pilot run. The crystalline phase of barium titanate can be observed clearly. PTC thermistors were made by the calcinated powders. The content of Sm is proportional to the resistivity of 25℃. The ratio of raw materials and the process of production need to be adjusted to get the electric characteristics of other applications.
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Fang, Jian-Zh, and 方建智. "Al doped ZnO films prepared by Sol-gel method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/42098775011659675224.
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碩士中原大學
物理研究所
100
In this study, we used the sol-gel method to prepare ZnO films and Al doped ZnO films. We investigated how the speed of spin coating, annealing temperature and annealing atmosphere affect the ZnO films, and how the Al doping affects the AZO films. In our experiments, we used scanning electron microscope (SEM) to analyze surface morphology, energy dispersive X-ray spectrometer (EDS) to measure sample composition, X-ray diffraction (XRD) to analyze crystal phase, photoluminescence (PL) to measure band gap, the van der Pauw method to measure resistivity, and UV/VIS spectrometer to measure transmittance of the ZnO and AZO films. Then we used these results to explain our experimental data. The resistivity of pure ZnO films prepared on glass substrates is about 30 Ω-cm. It reduces to about 0.02 Ω-cm after Al doping, and the transmittance of the films is higher than 80% in visible region. To decrease the resistivity, we annealed the sample in Ar to increase the vacancies of oxygen. Then we found that the resistivity of pure ZnO films decreases to ~8 Ω-cm and the resistivity of AZO films decreases to ~3×10-3 Ω-cm. The transmittance is still kept higher than 80%.
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Chen, Rei-Lin, and 陳瑞琳. "Preparing Electrochromic material Tungsten Oxide by Sol-Gel method." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/64645832319371835409.
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碩士逢甲大學
化學工程學所
92
Electrochromism is currently attracting more attentions from the academia and industries. There are many commercial applications for the electrochromic devices, such as sunroof window in a car, smart windows in order to balance the lighting in a house, antiglare mirror and electrochromic displays. Electrochromic materials include two types that are inorganic and organic ones. Especially for the inorganic type it can tolerate the dramatic environmentally changes, the typical materials are ITO, WO3 and NiOx, etc. The WO3 is the most investigated inorganic material, cause of its high transmittance difference. In this study sol-gel method is main concerned for the preparations of the tungsten oxide. The method has some advantages, which are low cost, easy to scale up to the large surface area and even the different aspect. At first, the solutions of sol-gel were prepared by using different precursor and catalyst (precursor : WOCl4 , WCl6), and spin-coating process used to deposit tungsten oxide film on the ITO glass, then conducted with the IR heat treatment. The deposited films were characterized by X-ray diffraction, scanning electronic microscopy and α-step film thickness. Several tungsten precursors were investigated in this study. The acid and base sol-gel solutions are also tested to observe the coloration of electrochromical films. From the CV/UV-VIS spectra we found that the sol-gal method is promising and WCl6 precursor is the better one.
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Huang, Hung-tai, and 黃鴻泰. "Preparation of WO3/V2O5 electrochromic glassby sol-gel method." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/58295080690905623848.
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碩士逢甲大學
化學工程學所
94
The rapid development of electrochromic materials has draw much attention to the academic research and technological application in recent years. The key to decide the electrochromic device in commercial purpose is the electrochromic performance and durability, such as response time, optical density change, cyclic lifetime and environmental test. In this study, sol-gel method is adopted to prepare the electrochromic films. It has advantages of low cost, and can be applied to large size of substrate. We use different factors of preparation to study the electrochromic performance and durability. After inserting Li+ ion into vanadium oxide film, the electrochromic device(ECD) with tungsten oxide film and vanadium oxide film is fabricated. The configuration of the device is Glass/ITO/WO3/electrolyte/V2O5/ITO/Glass. The performance of the device is evaluated by its cyclic lifetime and memory affect. Examined by the optical transmittance of color/bleach cyclic test, the tungsten oxide film shows the maximum transmittance change at λ=450nm. It attains about 46% with the optical density change of 0.33. Under the same condition, the vanadium oxide film gives the maximum transmittance change about 29% with the optical density change of 0.21. For the performance of the electrochromic device(ECD) with the size of 2.5 cm × 4 cm, it is found that the transmittance of the device can shift from 55% to 25% when a potential of ±2 V is applied. No deterioration is observed for up to 1000 cycles. The ECD prepared in this study also shows excellent memory characteristic.
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Fu, Chun-Hao, and 傅俊豪. "The preparation of TiO2 powder by Sol-Gel method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/8d63a3.
Full textAbstract:
碩士國立臺北科技大學
材料及資源工程系所
93
The purpose of this experiment is attempted to investigate Nano TiO2 in Sol-Gel method and analysis its physical characteristic. In the experiment process, the nitric acid and hydrochloric acid as the hydrolysis depressants, the product SiO2-Sol would be gained after hydrolysis. Therefore, make TGA/DTA to decides the temperature of calcining. In the same time, the functional-group analysis of Ti(OH)4 powder was demonstrated by FT-IR. Finally, we could gain Nano TiO2 powder after calcination. The basic characteristic of Nano TiO2 were analyzed: the particle size of powder was collected by Laser particle analysis, the morpography of the surface powder and particle size were observed by SEM. The result of XRD analysis reveal the phase of TiO2 is Anatase as the calcining temperature is about 450℃, the Rutile phase will appear at 500℃, the phase transform would be along with the exaltation of the calcining temperature. In the estimation of surface, we can find the calcining TiO2 powder has the good surface area by BET analysis (compare with business class types P-25), Under the SEM analysis, the powder gathering phenomenon would be observed.
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Cheng, Wen-Yang, and 鄭文禓. "Application the Sol-gel Method to Fabricate Magenta Pigment." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/07369216525435375881.
Full textAbstract:
碩士明新科技大學
化學工程與材料科技系碩士班
103
This paper presents the application of the sol-gel method to fabricate magenta pigment with aluminum isopropoxide as the foundation. We manipulated various factors during the experiment, including (1) the foundation, (2) the drug formula, (3) sintering temperature, and (4) sintering time to determine their influence on the color of the pigment. We found that to obtain a magenta toner, the number of chromium nitrate molarity must be fixed, as it controls the color of the pigment. Therefore, the primary factor manipulated was zinc nitrate, followed by the temperature and time of sintering.
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Liu, Chia Wei, and 劉家維. "Synthesis of Nanocrystalline Manganese Oxide by Sol-gel Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/55814368264607580446.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
97
Manganese oxides are important materials due to their wide-range applications, such as catalysts, electrochemical materials, soft magnetic materials, and for air purification. Nanostructured manganese oxide materials have unique properties in comparison with powder materials and recently have gathered increasing attention. In this study, the manganese oxides were prepared by surfactant-mediated method and the synthesis was accomplished by using triblock copolymer as the surfactant, by manganous acetate and manganous chloride as the inorganic precursors. TGA, XRD, FTIR, SEM, TEM and BET analyses were used to characterize the microstructure and morphology of the samples. The effect of experimental parameters such as calcination temperatures, the additive of precursors and NaOH on microstructure are discussed in this study. In this study, using 0.015 mol manganous acetate as the precursor and the sample calcined at 350℃ was composed of only Mn3O4. However, as the calcining temperatures were increased to 450 and 550℃, tricrystalline (Mn3O4, Mn2O3 and MnO2) were formed. But the crystal structure of the samples prepared with manganous acetate as precursor (any concentration of manganous acetate) and calcined at 350℃ were only Mn3O4. Using 0.015 mol manganous chloride as the precursor and the samples calcined at 350~550℃ were composed of a mixture of MnO2, Mn3O4 and Mn2O3 crystal structures (Mn3O4 was the main phase). The crystal structure of the samples prepared with manganous chloride as precursor (any concentration of manganous chloride) and calcined at 350℃ also showed the mixed phases of MnO2, Mn3O4 and Mn2O3. Using 0.005 M NaOH and the sample calcined at 350℃, demonstrates the coexistence of a mixed phase with Mn3O4 and Mn2O3. However, as the calcining temperatures were increased to 450 and 550℃, tricrystalline of MnO2, Mn3O4 and Mn2O3 were obtained.
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Hung, Cheng-Yen, and 洪晟晏. "Investigation of Electrochromism WO3 Films by Sol-gel Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/48750235790324103762.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
96
In recent years, electrochromism has been extensively utilized due to its potential application in smart windows utilized in architecture and those in automobile glazing. These have its repercussions in preventing energy wastage concomitant with modulation of light and solar radiation transmission.In this study, the precursor solutions were synthesized by sol-gel method while conventional low cost spin –coating technique was utilized for deposition of thin films, no need of high vacuum. Experimental results indicated that the WO3 films comprising of 2M H2O2 concentration exhibited the optimum electrochromic properties. WO3 films were found to retain their amorphous phase up to 300oC. The onset of the crystalline phase occurs at 400oC and it become completely crystalline at 500oC. After annealing the electrochromic properties of WO3 deteriorate, however their chemical stability is better than the amorphous counterparts. At the last, the polystyrene intermediate layer was used in order to generate porosity in the WO3 layers, eventually enhancing their surface area. This leads to improve its electrochromic properties and retent its chemical stability, which is the prime requisite for applications in smart windows.
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Li, Ming Cong, and 李明聰. "Synthesis of Mesoporous Tungsten Oxide by Sol-gel Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/33204086395658895278.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
95
Nanomaterials have unique properties in comparison with powder materials. Mesostructured materials with tailored pore structures and high surface areas in order to improve sensitivity have gathered increasing attention in recent years. In this study, mesoporous WO3 was prepared by sol-gel process and the synthesis was accomplished by using block copolymer as the template, and tungsten chloride as the inorganic precursor. We investigated the effects of synthesis variables on the structure of mesoporous WO3, such as the concentration of triblock copolymer, hydrolysis reaction, and the calcination temperatures. Thermo-gravimetric analysis, X-ray diffraction, transmission electron microscopy and N2 adsorption-desorption isotherms were used to characterize the microstructure of the samples. Mesoporous WO3 have been synthesized by using triblock copolymer F108 as a template and monoclinic structure were obtained after calcined at 300~400°C. The mesoporous WO3 is shown to have a high specific surface area of 129.5 m2/g as calcined at 300°C, and mesoporous structure was stable up to 350 °C. The addition of block copolymer can affect the structure of mesoporous. The addition of block copolymer increased from 0.1 to 1.0 g, and the specific surface area increased from 67.5 to 124.7 m2/g after calcined at 300°C. The microstructure of mesoporous WO3 is determined by the calcination temperature. From 300 to 400 ℃, the grain size increased from 6 to 12 nm, it can be seen that by increasing the calcined temperature a larger crystallite size is favored. Additionally, the crystallinity of mesoporous WO3 is controlled by the water content of the reaction system. From XRD results, the mesoporous WO3 with the better crystallinity are obtained with the increasing of the water content. Replaced with water from 0 to 50 %, the BET surface area decreased from 124.7 to 48.12 m2/g, but the average pore size increased from 7.79 to 14.098 nm after calcined at 300 ℃.
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Kai, Huang Chih, and 黃致凱. "Fabricate high voltage varistor by using the sol-gel method." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/78705900573688203663.
Full textAbstract:
碩士國防大學中正理工學院
應用化學研究所
92
The varistor precursor powders was fabricated by using the sol-gel method followed by calcination, ball milling, drying, pressing, sintering, electrode coating, and lead connecting to make a ZnO-based varistor. The more uniform and smaller particle size powders were made by sol-gel method. The experimental results showed that the stable gel was obtained during the precursor making step if the molar ratio of zinc nitrate to ethylene glycol was kept above 1:7. Furthermore, the mean particle size of the precursor powders was approximately 20nm after calcination of the gel. During the varistor preparation, the ZnO-based varistor with the better structure were obtained when the sintering temperature and the holding time was kept at 950℃ and one hour, respectively. The varistor through the sol-gel process has a high breakdown voltage 895V/mm and a nonlinear coefficient 58 compared to those through the conventional mixed oxide method. Through the pulse wave tests, the largest breakdown voltage is 4kV in the response time of 20ns. The experimental results reveal that the ZnO-based varistors with a high breakdown field through a sol-gel method can be applied on the use of high current circuits and the surge suppressor for the electromagnetic pulse protection.
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bo-jie, Jhang, and 張博傑. "ZrO2 S Type Optical Waveguide Prepared by Sol-gel Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/92944612487713852535.
Full textAbstract:
碩士明新科技大學
電子工程研究所
96
This project is to study optical waveguide of SiO2/ZrO2/SiO2/Si thin films deposited on Si(100) prepared by the sol-gel method. ZrO2 is an inexpensive, and wide band gap with high luminous transmittance, high refraction index, high K and hardness. The ZrO2 thin film can be deposited by a number of techniques such as RF sputtering, chemical vapor deposition (CVD), pulsed laser deposition, and sol-gel method. The sol-gel process has the advantage of large area deposition, in addition to its low cost and convenient process control. Hence the method is suitable for frontier researches. Then we use photolithography and etching to design optical waveguide patterns. We use light of He-Ne laser to test and verify our designed optical waveguide patterns if it can transmit light of He-Ne laser effort. ZrO2 sol-gel processes can be prepared under constant recipe and temperature. In this study, the effect of revolutions per minute (rpm) of spin coating and annealing temperature of the ZrO2 thin film processes on structural and optical properties derived the ZnO thin film can be investigated. XRD, SEM, ellipsometer, and photoluminescence measurements investigate structural and optical properties.
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何祐誠. "Study of the Thermochromic VO2 Film by Sol-Gel Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/72794914703628512333.
Full textAbstract:
碩士明新科技大學
化學工程研究所
95
In this study, a combination technique, sol-gel method and spin-coating was used to prepare the VO2 thin film. The optical property of the prepared thin film was characterized by the UV-Vis / NIR Spectrometer. In addition, analytical instruments of SEM and XRD were also employed to investigate the morphology and the crystallinity of the synthesized VO2 thin film. Furthermore, Universal tester was applied to study the adherence between VO2 thin film and glass. Results showed that the synthesized VO2 thin film had a better thermochromic effect during the calcination temperature between 475 to 500℃. Moreover, the thermochromic transition temperature can be tuned down from 68℃ to 30℃ as a small amounts of W6+ were doped into the VO2 thin film. However, while SiO2 was added into the film, an inhibition of the VO2 nucleation was observed, but the transparency was enhanced simultaneously. Further, the adherence of the synthesized film depended on both factors of calcination temperature and amounts of W6+ dopant. The adherence was almost linearly increased with calcination temperature.
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Feng, Hsiao Jen, and 蕭人逢. "The Preparation of Chitosan / Silica Hybrid by Sol-Gel Method." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/07079009758636199871.
Full textAbstract:
碩士中國文化大學
材料科學與製造研究所
90
Abstract The combination of sols containing silica polymers, prepared by the sol-gel method under conditions of nearly linear chain growth, with solutions of the biopolymer chitosan has allowed us to obtain hybrid materials in the form of films or particles. Aquagels, where the solid phase consists of both chitosan and silica, can be easily prepared by using an acidic solution of chitosan to catalyze the hydrolysis and condensation of tetraethylorthosilicate. The chitosan and the oligomer of silicon ethoxide were mixed in acidic water and the oligomer of silicon ethoxide was hydrolyzed, polycondensed and cross-linked with the hydroxyl group of chitosan. This chitosan-silica solution was cast in a polypropylene’s vessel to make a uniform membrane of chitosan/ silica hybrid. The aim of this research is to prepare monodispersed slica and chitosan particles with nano-hybrid materical. That is confirmed through SEM、FT-IR、XRD、BET and UV-Vis measurements. Lysozyme test has been carried out to show enzymatic hydrolysis behavior for resulting chitosan/silica hybrid. In addition, the prepared hybrid materical can’t be dissolved in orginal acid solution, which indicates chitosan has been immobilized within silica. Similar order of adsorption capacity has also been achieved when compared with chitosan and silica.
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Huang, C.-Ju, and 黃政儒. "Transparent Conducting ZnO:B Thin Films Deposited by sol-gel method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/96093130764713466347.
Full textAbstract:
碩士義守大學
材料科學與工程學系碩士班
94
Transparent conducting thin films deposited by sol gel method. It makes advantage of expenses reduce to deposit films under room temperature, and not need expensive vacuum equipment, etc. We can make up by controlling the solution, and change the composition of the transparent conducting thin films. In recent years, making the improvement of the fabrication method has already become equal character of thin films with sputtering deposition method. The electrical conductivity of pure zinc oxide is not enough high. In order to improve the electrical conductivity of zinc oxide thin films which prepared by the sol gel method. Increasing doped with boron atom, when the solution is prepared. We want to replace Zn2+ by B3+ so as to produce more the free electron. Concentration of boron atom is at 0.1 at% ~ 2.0 at%. Heat treatment in different annealing temperature is at 350 oC、450 oC、550 oC、650 oC. The experimental result shows that the concentration of boron atom at 0.7 at% can get the best electrical conduction, so the electrical property increased with increasing doping concentration. Annealing temperature rising contributes to forming zinc oxide films. It has better properties that the films with 0.7 at% boron doping concentration zinc oxide films, and heat treatment temperature at 550 oC. the zinc oxide surface exhibits smooth and compacts structure, because its crystallization is better, The transmittance is more than 80%, too. However, the electron conduction still can be improved, so we fix the composition (0.4 M and 0.7 at% B) of the regular solution in this experiment and change and make a parameter, such as heat treatment at different atmosphere, thickness of the thin films, concentration of the solution, and pH value of the solution, etc. It can find out the best solution composition and heat treatment condition. Making character analysis just like micro-structure, surface shape, composition, electrical and optics properties is with a view to researching the parameter changes for zinc oxide films In different parameters, they have better properties which the films with 0.7 at% boron doping concentration zinc oxide films, and heat treatment at 550 oC, while in reducing atmosphere (95 %H2 + 5 %N2). The better properties could be explained by the absorption of oxygen in grain boundaries which act as traps for the carriers, leading to an increase in the carrier’s concentration when the annealed treatment is performed in reduced atmosphere. And heat treatment in reduce atmosphere, it can take oxygen atom away and make films produce more oxygen vacancy. And the reduced atmosphere will make the crystallization of the films lower; it is helpless to the forming of the zinc oxide. So when the flow is too high, it debased the electrical and optical properties of the films.
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Lin, Hong-Xun, and 林宏勳. "The Study of Transparent Conducting Films by Sol-Gel Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/43798450555370581898.
Full textAbstract:
碩士元智大學
電機工程學系
98
Because of low resistivity and high transmission characteristic , therefore TCO is always used for Optoelectronic Devices .The common methods of TCO are Evaporation、sputter、Chemical Vapor De- position and the sol- gel . To mand Indium-Tin Oxide(ITO) by evaporation , It has advanta- ges of film thickness、low resistivity and high transmission ,but it also has disadvantage of expensive equipment and long time of process .How to reduce cost and decrease process time are two important topics . In this experiment , We made TCO by sol-gel . Then we found that the SnCl2 dopes under 16wt% , and use 500℃ to anneal thickness 2500Å in 15 minutes , then the resistivity is 11Ω and the transmission is 80% , It is the best optical and electrical characteristics . The way use in process of LED , at As type , when input current is under 50mA , the brightness is bigger than use evaporation method of ITO , but if use the process in bonding process , the LED will have a serious peeling issue .
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Fang, Sheng Yu, and 方聖予. "Preparation of Mesoporous Yttria-Stabilized Zirconia by Sol-Gel Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26241528448898498953.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系
98
Since the mesoporous silica material, MCM-41 has been presented by Mobil company in 1922, there has been much interest in expanding the compositions of mesoporous inorganic materials. The mesoporous materials exhibit many applications due to the high specific surface area, uniform pore size and the adjustment of pore size.In this study, the mesoporous yttria-stabilized zirconia(YSZ) and nickel oxide/YSZ(NiO/YSZ) were prepared by sol-gel process and the complexes were synthesized by using block copolymer as the templates, and ZrCl4, YCl3, Ni(NO3)2 as the inorganic precursors. TGA, XRD, TEM and N2 adsorption-desorption isotherms measurement were used to analyze the specific surface area and characterize the microstructure of the samples. The effects of experimental parameters, such as molar ratio of Yttrium, concentration of triblock copolymer and calcination temperatures, on pore morphology and specific surface area were discussed.The mesoporous YSZ and NiO/YSZ have been synthesized with high surface area, about 114.2 m2/g and 103.4 m2/g, uniform pore size about 3.3 nm and 5.9 nm. There are four important results obtained in this study. First, the addition of YCl3 resulted in the decrease of reaction rate of condensation, increase of the micellization and high surface area, stability of the crystalline structures of ZrO2 i.e., cubic phase, high surface area and uniform pore sizes of mesoporous YSZ. Second, the highly ordered mesoporous materials were obtained by mixing proper ratio of surfactant and inorganic precursor. Third, the mesopores were collapsed with increased temperctures. Fourth, the addition of Ni(NO3)2 inhibited the reaction rate of condensation. The mesoporous NiO/YSZ was synthesized with low concentration block copolymer exhibited high surface area, wormhole-like structures by TEM observation. Keywords: YSZ, sol-gel method, block copolymer, mesoporous materials
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Huang, Chi-Liang, and 黃啟量. "Preparation of transparent conductive ZnO：Al film by sol-gel method." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36201757018910775513.
Full textAbstract:
碩士中興大學
電機工程學系所
99
The main purpose of this thesis is to fabricate the transparent conductive AZO (ZnO：Al) film by sol-gel method, the atomic ratio of Al and Zn in AZO film is 1 to 100. The films were spin coated on Eagle 2000 glass with strain point 666 ℃. The annealing temperature is operated between 400 to 800 ℃ which is across the strain point. The result shows that 700 ℃ anneal has the best resistivity, but reveals the worst transmittance in the visible region. The resistivity is more than ten times lower than that of the samples receiving other annealing temperature. The transmittance of 700 ℃ annealed samples is more than 86 % which is about 3 to 4 % less than that of samples with different anneal temperatures. Different annealing ambient is also carried out in this research , the samples under vacuum annealing reveals the highest transmittance; samples annealed in air reveals a better surface in smoothness , while the samples annealed in nitrogen has the best crystallinity and lowest resistivity. In addition, the cooling down process is modified with three different schemes; the slow cooling in vacuum can lead to the lowest resistivity. The improvement can be as high as 30 to 180 folds. AZO films were then treated in hydrogen plasma with different RF power from 25 W to 100 W. The resistivity can be reduced to at least 65 % with hydrogen plasma treatment. Finally, the samples were aged in air at room temperature for 30 days to see the stability of the AZO films. For both plasma treated and un-treated samples, the resistivity all increased two folds after 30 days. This aging result implicates that hydrogen plasma treatment can also effectively prevent the aging of the AZO films treatment AZO thin films.
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Liu, Chan-Chin, and 劉展志. "Electrochromic MoO3 thin films derived from a sol-gel method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/87961614035146399567.
Full textAbstract:
碩士正修科技大學
電機工程研究所
96
Electrochromic molybdenum trioxide (MoO3) films were deposited on ITO/Glass substrates using a sol-gel process in this study. The effects of heat-treatment temperature (150 ~ 500℃), ambient atmosphere (Vacuum, N2, Air and O2), thin film thickness (76 ~ 294 nm) and electrolyte concentration (0.5 ~ 2 M) on the electrochromic properties of MoO3 films were investigated by cyclic voltammetry (CV) in propylene carbonate (PC) non-aqueous solution containing lithium perchlorate (LiClO4). Experimental results showed that the amorphous MoO3 films can be obtained at heating temperatures below 300℃ in oxygen ambient atmosphere. The optimal electrochromic MoO3 film with a thickness of 130 nm and electrolyte concentration of 1 M exhibited a maximum transmittance variation of 30.1%, an optical density change of 0.213, an insertion charge of 8.47 mC/cm2 and a coloration efficiency of 25.1 cm2/C between the colored and the bleached states at the wavelength of 550 nm.