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Synthesis and characterization of CeO2-Bi2O3 solid solution

dc.contributor.advisorKremenović, Aleksandar
dc.contributor.otherKaranović, Ljiljana
dc.contributor.otherMatović, Branko
dc.creatorPrekajski, Marija D.
dc.date.accessioned2016-08-27T16:04:15Z
dc.date.available2016-08-27T16:04:15Z
dc.date.available2020-07-03T09:10:33Z
dc.date.issued2014-04-04
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=3664
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/6348
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:12470/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=45734927
dc.description.abstractNanoprahovi kristalnih faza iz serije čvrstih rastvora u pseudo-binarnom sistemu CeO2-Bi2O3 sintetisani su primenom jednostavne i ekonomične samopropagirajuće metode na sobnoj temperaturi korišćenjem nitrata metala i natrijum-hidroksida kao polaznih supstanci. Osim krajnjih članova niza, CeO2 i niskotemperaturne polimorfne modifikacije α-Bi2O3, sintetisani su i čvrsti rastvori nominalnog sastava Ce1-xBixO2-δ, gde je x = 0,1; 0,2; 0,3; 0,4; 0,5; 0,6; 0,7; 0,8; 0,9. Rezultati proučavanja metodom rendgenske difraktometrije na polikristalnom materijalu i ramanske spektroskopske analize pokazali su da su sintetisani prahovi sa nižim sadržajem bizmuta (x = 0,1 – 0,5) monofazna jedinjenja koja kristališu teseralno sa fluoritskim tipom strukture, kakvu imaju CeO2 i visokotemperaturna polimorfna modifikacija, δ-Bi2O3. Utvrđeno je da granica rastvorljivosti jona Bi3+ u strukturi CeO2 iznosi 50 at.% Bi i da sa povećavanjem sadržaja Bi iznad 50 at.% dolazi do izdvajanja sekundarne faze, α-Bi2O3. Veličine kristalita za sva sintetisana jedinjenja su nanodimenzione sa prosečnom veličinom manjom od 5 nm, izuzev u slučaju α-Bi2O3, čija veličina kristalita iznosi 541 nm. Iz Ritveldove analize difrakcionih podataka dobijenih na polikristalnim uzorcima koji sadrže do 50 at.% Bi, proizilazi da se sa porastom koncentracije Bi i ugradnjom većeg jona Bi3+ na mesto manjeg Ce4+, povećavaju parametri a jediničnih ćelija dok rezultati analize difrakcionih profila pokazuju porast mikrostrukturnih naprezanja. Hemijski sastav sintetisanih čvrstih rastvora, koji je određen pomoću skenirajuće elektronske mikroskopije u kombinaciji sa EDS analizom, približno je jednak željenom, tj. nominalnom sastavu. Sintetisani prahovi pokazuju strukturu neuniformno raspoređenih rastresitih aglomerata sa srednjom veličinom čestica od 0,1 do 0,4 μm. Optička svojstva proučavana su metodom spektroskopske elipsometrije, pri čemu je utvrđeno da dopiranje niževalentnim jonima Bi3+ dovodi do pomaka energijskog procepa ka nižim energijama, tj. apsorpciona granica Ce1-xBixO2-δ pomera se ka vidljivom delu spektra, u odnosu na nedopiran CeO2, kod kojeg se apsorpciona granica nalazi u UV oblasti...sr
dc.description.abstractA series of nanocrystalline powders of solid solutions in pseudo-binary CeO2-Bi2O3 system has been prepared from metal nitrates and sodium hydroxide using the simple and cost effective self-propagating room temperature reaction. Besides the end-members of the sequence, CeO2 and low-temperature polymorphic modification, α-Bi2O3, solid solutions with nominal composition Ce1-xBixO2-δ, x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, were also synthesized. The results of the study by X-ray powder diffraction and Raman spectroscopic analyses showed that the synthesized powders with lower bismuth contents (x = 0.1 – 0.5) are monophased samples which have the bodycentered cubic fluorite-type structure like CeO2 and high-temperature polymorphic modification, δ-Bi2O3. The experimentally determined solubility limit of Bi3+ in the crystal structure of CeO2 is 50 at.% of Bi3+ ions. The increase of Bi quantity above 50 at.% causes the formation of the α-Bi2O3 as a secondary phase. Crystallite size of all synthesized powders is in the nanometric range with an average less than 5 nm in size, except in the case of α-Bi2O3 where the crystallite size is 541 nm. The Rietveld and diffraction profile analysis of samples containing up to 50 at.% Bi showed that the unit cell parameter a and microstrains increase with the increasing of bismuth amount and the entrance of the larger Bi3+ ion at the Ce4+ position. The chemical composition of the synthesized solid solutions, which was determined by scanning electron microscopy coupled with EDS analysis, is very close to the desired nominal one. The synthesized powders have the structure of non-uniform spread of loose agglomerates with average particle sizes ranging from 0.1 to 0.4 μm. The optical properties were studied using spectroscopic ellipsometry. It was shown that the incorporation of Bi3+ ions of lower oxidation state than Ce4+ in CeO2 leads to a shift of the energy gap to lower energies. This is associated with the shift of the absorption limit of Ce1-xBixO2-δ solid solutions toward the visible spectrum compared to the undoped CeO2 in which the absorption limit is in the UV range...en
dc.formatapplication/pdf
dc.languagesr
dc.publisherУниверзитет у Београду, Рударско-геолошки факултетsr
dc.relationinfo:eu-repo/grantAgreement/MESTD/Integrated and Interdisciplinary Research (IIR or III)/45012/RS//
dc.rightsopenAccessen
dc.sourceУниверзитет у Београдуsr
dc.subjectnanostrukturni materijalisr
dc.subjectnanostructured materialsen
dc.subjectčvrsti rastvorisr
dc.subjectCeO2sr
dc.subjectBi2O3sr
dc.subjectrendgenska difraktometrija prahasr
dc.subjectRitveldova metodasr
dc.subjectmikrostrukrurna analizasr
dc.subjectsolid solutionsen
dc.subjectCeO2en
dc.subjectBi2O3en
dc.subjectX-ray powder diffractionen
dc.subjectRietveld refinement methoden
dc.subjectmicrostructural analysisen
dc.titleSinteza i karakterizacija nanoprahova u CeO2-Bi2O3 sistemusr
dc.titleSynthesis and characterization of CeO2-Bi2O3 solid solutionen
dc.typedoctoralThesis
dc.rights.licenseBY-NC
dcterms.abstractКременовић, Aлександар; Матовић, Бранко; Карановић, Љиљана; Прекајски, Марија Д.; Синтеза и карактеризација нанопрахова у ЦеО2-Би2О3 систему; Синтеза и карактеризација нанопрахова у ЦеО2-Би2О3 систему;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/15142/Disertacija4313.pdf


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