Microstructure evolution and oxidation states of Co in perovskite-type oxide Ba_(1.0)Co_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) annealed in CO_2 atmosphere

作     者：Chengzhang Wu He Wang Xingxing Zhang Yuwen Zhang Weizhong Ding Chenghua Sun 

作者机构：Shanghai Key Laboratory of Modern Metallurgy and Materials Processing Shanghai University School of Chemistry Monash University Clayton VIC 3800 Australia 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2014年第23卷第5期

页      面：575-581页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 070301[理学-无机化学] 

基　　金：supported by the National Natural Science Foundation of China(No.51274139,51174133) the Innovation Program of Shanghai Municipal Education Commission(13YZ019) the Doctoral Fund of Ministry of Education of China(20123108120020) the Innovative Foundation of Shanghai University 

主　　题：perovskite oxygen permeation carbon dioxide corrosion sulfate 

摘      要：Ba1.0Co0.7Fe0.2Nb0.1O3-γ（BCFN） oxide with perovskite cubic structure was synthesized by solid state reaction method. COa corrosion of BCFN membrane was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, diffuse reflectance infrared Fourier- transformed spectroscopy （DRIFT） and X-ray absorption fine structure spectroscopy （XAFS）. Cobalt （Co） K-edge absorption spectra of BCFN annealed in COa reveal that the oxidation states of Co in all the samples were larger than ＋3 and they decreased with the increase of calcination time. At 800 ℃, 1% CO2 introduced into He could speed up the reduction of Co cations in comparison with pure He. In addition, sulfate ions in the bulk of BCFN membrane preferred to migrate to the surface under CO2 calcination and form monoclinic Ba（CO3）0.9（SO4）0.1 besides orthorhombic witherite. Moreover, SEM results indicate that the nucleation and growth of carbonates grains started at the grain boundary of the membrane.