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Priprava lantanovega galata iz mešanega sistema reducentov in nitrata
Zupan, Klementina (Author), Maček, Jadran (Author), Pejovnik, Stane (Author), Kapun, Barbara (Author)

URLURL - Presentation file, Visit http://www.dlib.si/details/URN:NBN:SI:DOC-793YRYPZ This link opens in a new window

Abstract
Lantanov galat (LaGaO3), dopiran z dvovalentnimi elementi, je ionski prevodnik tako v oksidativni kot reduktivni atmosferi z zanemarljivo elektronsko prevodnostjo in je zato možen material za elektrolit za novo generacijo keramičnih gorivnih celic, ki bodo delovale pri temperaturah okoli 800 [kompozitum]C. nastaja v binarnem sistemu La2O3-Ga2O3 kot ena od dveh spojin, druga spojina je La4Ga2O9. Nedopiran lantanov galat smo pripravljali z zgorevalno sintezo iz raztopin v sistemu kovinski nitrati - urea in/ali citronska kislina. Pri sintezi iz reakcijskih zmesi mešanih reducentov poteka sinteza pri višji temperaturi kot pri uporabi enega samega reducenta. Pri sintezah s stehiometrijskim razmerjem med reducentom (ureo ali cintronsko kislino) in nitrati samovzdrževalna reakcija poteče, vendar je temperatura sinteze prenizka za nastanek lantanovega galata. V mešanem sistemu reducentov, kjer predpostavljamo, da ena vrsta kovinskih ionov reagira s citronsko kislino, druga pa z ureo, se reakcija intenzivira. Po sintezi z mešanim reducentom (citronska kislina / urea = 1/3) in po predgrevanju reakcijske zmesi v komorni peči pri 500 [kompozitum]C smo z rentgensko praškovno analizo detektirali lantanov galat. Za primerjavo smo lantanov galat pripravili tudi s kalcinacijskim postopkom iz La(OH)3 in Ga2O3. Perovskitna oblika se prvič pojavi po žganju pri temperaturi 1000 [kompozitum]C.

Language:Slovenian
Keywords:lantanov galat, mešani reducent, zgorevalna sinteza
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:FKKT - Faculty of Chemistry and Chemical Technology
Year:2004
Publisher:Inštitut za kovinske materiale in tehnologije
Number of pages:str. 171-175
Numbering:Letn. 38, št. 3/4
UDC:546.654:543.57
ISSN on article:1580-2949
COBISS.SI-ID:360362 Link is opened in a new window
Views:597
Downloads:159
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Record is a part of a journal

Title:Materiali in tehnologije
Shortened title:Mater. tehnol.
Publisher:Inštitut za kovinske materiale in tehnologije
ISSN:1580-2949
COBISS.SI-ID:106193664 This link opens in a new window

Secondary language

Language:Unknown
Title:Lanthanum gallate preparation from a mixed reductant-nitrate system
Abstract:
Lanthanum-gallate-based material is a candidate for the electrolyte in a new generation of low-temperature ceramic fuel cells due to its good ionic and negligible electronic conductivity. Lantn[!]an[!]um gallate is one of two compounds in the binary system La2O3-Ga2O3 together with La4Ga2O9. Undoped lanthanum gallate was prepared using combustion synthesis from metal nitrates and a reducing agent (urea and/or citric acid). In the mixed-fuel-type system the reaction intensifies and higer temperatures are achieved than in the redox system with one reducing agent. In the systems with one reducing agent a self-sustaining reaction occurs, but the temperature is too low for lanthanum gallate formation. In the mixed reducing system we used the principle where one cation reacts with the urea and the other with citric acid. The ratio between the citric acid and the urea was calculated to be 1:3. The combustion was carried out in a chamber furnace to increase the reaction mixture is starting temperature to 500 [compositum]C. In the product, lanthanum gallate was determined using X-ray powder diffraction. Whenlanthanum gallate was prepared by the calcining method from La(OH)3 the perovskite modification first appeared after calcination at 1000 [compositum]C.

Keywords:lanthanum gallate, mixed reducing agents, combustion synthesis

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