钙钛矿型复合氧化物LaM_yM_（1－y）~＇O_3的氧化还原性能的研究  

Redox Property of Perovskite-type Mired Oxides LaM_yM_(_1-y)′O_3

作　　者：刘社田[1] 于作龙[1] 吴越[1] 

机构地区：[1]中国科学院长春应用化学研究所,中国科学院大连化学物理研究所催化重点实验室博士后流动站

出　　处：《无机材料学报》1994年第4期443-449,共7页Journal of Inorganic Materials

基　　金：国家自然科学基金

摘　　要：用ＴＰＲ、ＸＲＤ和ＸＰＳ手段研究了Ｂ位二元复合钙钛矿型复合氧化物ＬａＭｙＭＯ３（Ｍ、Ｍ’＝Ｍｎ、Ｆｅ、Ｃｏ；ｙ＝０．０～１．０）中过渡金属离子的氧化还原性能和还原过程·ＬａＭｎＯ３和ＬａＣｏＯ３及富Ｍｎ和富Ｃｏ样品的还原分为两步：第一步对应于高价过渡金属离子的还原，且不破坏钙钛矿的骨架结构，但可使晶体的对称性及缺陷浓度发生改变；第二步还原使钙钛矿结构破坏，还原产物中出现单元氧化物和金属单质如Ｌａ２Ｏ３、ＭｎＯ、Ｃｏ．ＬａＦｅＯ３和富铁样品的还原过程比较复杂，温度低于１１２３Ｋ时结构基本保持不变，此温度范围内的还原主要是缺陷浓度的变化和高价金属离子数量的减少，第二种离子的加入及其之间的相互作用对样品的还原温度和氧化还原性能有明显的影响，这种影响的程度与样品的结构有关．Ｍｎ、Ｆｅ、Ｃｏ离子的氧化还原性能的强弱可用如下的反应表示：The Redox property and reduction procedure of transition metal ions of B-site mired perovskite-type oaldes LaMyMO3(M、M'=Mn' Fe、Co) were studied employing TPR, XRD and XPS techniques.The reduction of LaMnO3 and LaCoO3 as well as Mn-rich and Co-rich samples proceeds on two stages,each corresponding to the reduction of the higher valent ion to the lower. The lattice framework could be maintained in the first stage for the reduction of Mn(4+) and Co(3+), but the lattice symmetry and the defect concentration could be changed. The reduction of lower valent ions (Mn(3+), Co(2+)) in the second stage would destroy the lattice framework and there appeared in the reduced products La2O3, MnO and Co. The reduction of LaFeO3 and Fe-rich samples was complicated. The crystal structure could be maintained when the reduction temperature was below 1123K, which was mainly due to the change of defect concentration and the decrease of higher valent ions. The doping with foreign ions in.B-site and the interaction between defferent transition metal ions could modify, on some extent relating to thecrystal structure, the redox property and the reduction temperature. The Redox property of Mn, Fe, Coions could be expressed as the following equations:

关 键 词：钙钛矿 复合氧化物 氧化还原性能 程序升温还原 

分 类 号：O613.3[理学—无机化学]