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

  • 황호순 (성균관대학교 이과대학 화학과) ;
  • 박일현 (성균관대학교 이과대학 화학과)
  • Published : 19940400


Perovskite-type mixed oxides LaBO$_3$(B = Mn, Fe, Co) were prepared by citrate sol-gel method in $air(850^{\circ}C$, 24h). The oxygen stoichiometries and structures of these oxides were determined by XRD and TPR results as followings; LaMnO$_{3.16}$(a = 5.507, c = 13.329 $\AA$, hexagonal), LaFeO$_{3.17}$(a = 5.554, b = 5.555, c = 7.863 $\AA$, orthorhomibic), LaCoO$_{3.0}$(a = 5.436, c = 13.095 $\AA$, hexagonal). The temperature programmed reduction(TPR) experiments in static 300 torr H$_2$ atmosphere shows that the reduction reaction of LaBO$_3$(B = Mn, Fe, Co) proceeds into two stages, and thermal stabilities of these oxides decreased in the order of LaMnO$_3$ > LaFeO$_3$ > LaCoO$_3$. According to the kinetic analysis the lowest activation energy was obtained for LaCoO$_3$.



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