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Obtaining of lanthanum-gallate for fuel cells application

dc.contributor.advisorSrdić, Vladimir
dc.contributor.otherNikolić, Ljubica
dc.contributor.otherSrdić, Vladimir
dc.contributor.otherStojanović, Goran
dc.creatorStijepović, Ivan
dc.date.accessioned2018-10-15T11:08:31Z
dc.date.available2018-10-15T11:08:31Z
dc.date.available2020-07-03T13:54:54Z
dc.date.issued2012-12-28
dc.identifier.urihttps://nardus.mpn.gov.rs/handle/123456789/10031
dc.identifier.urihttps://www.cris.uns.ac.rs/DownloadFileServlet/Disertacija139409817507776.pdf?controlNumber=(BISIS)85671&fileName=139409817507776.pdf&id=1494&source=NaRDuS&language=srsr
dc.identifier.urihttps://www.cris.uns.ac.rs/record.jsf?recordId=85671&source=NaRDuS&language=srsr
dc.identifier.urihttps://www.cris.uns.ac.rs/DownloadFileServlet/IzvestajKomisije153899168789886.pdf?controlNumber=(BISIS)85671&fileName=153899168789886.pdf&id=12102&source=NaRDuS&language=srsr
dc.description.abstractU ovom radu su sintetisani prahovi na bazi lantan-galata, citratnom sol-gel metodom i hemijskom sintezom u parnoj fazi (CVS), a njihovim presovanjem i sinterovanjem su dobijeni keramički uzorci kontrolisane mikrostrukture. Cilj disertacije je bio dobijanje guste keramike koja bi mogla da se primeni kao jonski provodni elektrolit u gorivnim ćelijama sa čvrstim elektrolitom (SOFC), a koje bi radile na srednjim temperaturama od 500–700 °C (IT-SOFC). Po prvi put su sintetisani nanoprahovi lantan-galata u gasnoj fazi i utvrđeno je da ovako dobijeni polazni prahovi, zbog svojih superiornih karakteristika omogućavaju snižavanje temperature sinterovanja za 150 °C, što je veoma povoljno kako sa stanovišta dizajniranja mikrostrukture, tako i zbog uštede energije u procesu proizvodnje gorivnih ćelija. Ipak, zbog nedovoljne kontrole hemijskog sastava i stehiometrije sintetisanih prahova, što je i najveći nedostatak CVS metode dobijanja perovskitnog LaGaO3, nije bilo moguće dobiti keramiku koja bi ispunjavala zahteve za primenu u SOFC. S druge strane, citratna sol-gel metoda pruža veliku kontrolu pomenutih parametara zbog čega je bila moguća sinteza čitavog niza čvrstih rastvora lantan-galata. Ovom metodom su tako sintetisani čist lantan-galat (LG) i dopirani prahovi kod kojih je deo lantana supstituisan stroncijumom, 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 sintetisani prahovi su zahtevali naknadnu kalcinaciju na 900 °C, ali su potrebne gustine (>95% teorijske gustine) postignute sinterovanjem na temperaturi od 1450 °C već nakon 2 h, što je izuzetno kratko imajući u vidu literaturne podatke. Takođe, sinterovani uzorci su po faznom sastavu bili čista LSGM keramika, a impedansna merenja su pokazala da je najveću provodljivost imao uzorak La0,85Sr0,15Ga0,8Mg0,2O3-. Ovaj sastav je dalje korišćen u cilju provere mogućnosti 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 i LSGMC). Pokazano je da dodatak male količine prelaznih metala značajno utiče na mehanizam provođenja, ali da je na višim temperaturama jonska provodljivost i dalje dominantna. Konstatovano je da se dodavanjem male količine Ni ili Co u LSGM mogu dobiti materijali koji bi služili kao elektroliti u IT-SOFC, pri čemu je potencijal nikla kao dopanta nešto veći nego kobalta.sr
dc.description.abstractPowders 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.en
dc.languagesr (latin script)
dc.publisherУниверзитет у Новом Саду, Технолошки факултетsr
dc.rightsopenAccessen
dc.rights.urihttps://creativecommons.org/licenses/by-nd/4.0/
dc.sourceУниверзитет у Новом Садуsr
dc.subjectLantan-galatsr
dc.subjectLanthanum-gallateen
dc.subjectFuel Cellsen
dc.subjectNanopowder synthesisen
dc.subjectCVS Citrate sol-gel methoden
dc.subjectImpedance Spectroscopyen
dc.subjectConductivityen
dc.subjectGorivne ćelijesr
dc.subjectSinteza nanoprahovasr
dc.subjectCVSsr
dc.subjectCitratna sol-gel metodasr
dc.subjectImpedansna spektroskopijasr
dc.subjectProvodljivostsr
dc.titleDobijanje lantan-galata za primenu u gorivnim ćelijamasr
dc.title.alternativeObtaining of lanthanum-gallate for fuel cells applicationen
dc.typedoctoralThesisen
dc.rights.licenseBY-ND
dcterms.abstractСрдић, Владимир; Срдић, Владимир; Стојановић, Горан; Николић, Љубица; Стијеповић, Иван; Добијање лантан-галата за примену у горивним ћелијама; Добијање лантан-галата за примену у горивним ћелијама;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/40446/Disertacija.pdf
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/40447/IzvestajKomisije.pdf
dc.identifier.fulltexthttps://nardus.mpn.gov.rs/bitstream/id/40447/IzvestajKomisije.pdf
dc.identifier.fulltexthttps://nardus.mpn.gov.rs/bitstream/id/40446/Disertacija.pdf
dc.identifier.rcubhttps://hdl.handle.net/21.15107/rcub_nardus_10031


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