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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 38, Number 4
JKCSEZ 38(4)
August 20, 1994 

 
Title
Reactivity and Preparation of Perovskite-Type Mixed Oxides LaBO3(B = Mn, Fe, Co) by Citrate Sol-Gel Method

Citrate Sol-Gel법에 의한 Perovskite형 복합 산화물 LaBO3(B = Mn, Fe, Co)의 생성 및 환원 반응성
Author
Ho-Soon Hwang, Il-Hyun Park

황호순, 박일현
Keywords
Abstract
Citrate sol-gel법을 이용하여 perovskite형 복합산화물 LaBO3(B = Mn, Fe, Co)을 공기 중 850℃에서 24시간 동안 소성하여 제조하였다. X-선 회절분석(XRD)과 TPR결과에 의하면 이들 산화물의 결정구조와 산소화학양론은 LaMnO3.16(a = 5.507, c = 13.329 Å, hexagonal), LaFeO3.17(a = 5.554, b = 5.555, c = 7.863 Å, orthorhomibic), LaCoO3.0(a = 5.436, c = 13.095 Å, hexagonal)으로 수소 분위기(300torr)에서의 TPR결과에 의하면 이들 산화물은 2단계 환원반응으로 반응이 진행되며, 열적안정성은 LaMnO3 > LaFeO3 > LaCoO3순으로 나타났고, 반응속도론적 결과 역시 LaCoO3의 활성화에너지 값이 가장 낮음을 보였다.

Perovskite-type mixed oxides LaBO3(B = Mn, Fe, Co) were prepared by citrate sol-gel method in air(850℃, 24h). The oxygen stoichiometries and structures of these oxides were determined by XRD and TPR results as followings; LaMnO3.16(a = 5.507, c = 13.329 Å, hexagonal), LaFeO3.17(a = 5.554, b = 5.555, c = 7.863 Å, orthorhomibic), LaCoO3.0(a = 5.436, c = 13.095 Å, hexagonal). The temperature programmed reduction(TPR) experiments in static 300 torr H2 atmosphere shows that the reduction reaction of LaBO3(B = Mn, Fe, Co) proceeds into two stages, and thermal stabilities of these oxides decreased in the order of LaMnO3 > LaFeO3 > LaCoO3. According to the kinetic analysis the lowest activation energy was obtained for LaCoO3.

Page
276 - 282
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