高温还原La_(1–x)Sr_(x)Cr_(0.5)Mn_(0.5)O_(3)钙钛矿的晶体结构研究  

Crystal Structure of La_(1–x)Sr_(x)Cr_(0.5)Mn_(0.5)O_(3) Perovskites Reduced at High-Temperature

作　　者：陈冬梅 徐序 罗凌虹 王乐莹 程亮 余剑峰 杭琪 CHEN Dongmei;XU Xu;LUO Linghong;WANG Leying;CHENG Liang;YU Jianfeng;HANG Qi(School of Materials Science and Engineering,Jingdezhen Ceramic University,Jingdezhen 333403,Jiangxi,China;National Engineering Research Center for Domestic&Building Ceramics,Jingdezhen 333001,Jiangxi,China;Jiangxi Provincial Key Laboratory of Fuel Cell Material and Devices,Jingdezhen Ceramic University,Jingdezhen 333001,Jiangxi,China)

机构地区：[1]景德镇陶瓷大学材料科学与工程学院,江西景德镇333403 [2]国家日用及建筑陶瓷工程技术研究中心,江西景德镇333001 [3]景德镇陶瓷大学江西省燃料电池材料与器件重点实验室,江西景德镇333001

出　　处：《硅酸盐学报》2024年第6期1832-1840,共9页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(51762026,51802132);江西省自然科学基金重点项目(20224ACB204010);江西省教育厅科技落地计划(KJLD13072);江西省教育厅科技项目(GJJ2201009,GJJ2201010);景德镇市科技计划项目(2023GY001-06);景德镇市科技计划项目(20234ST005)。

摘　　要：La_(1–x)Sr_(x)Cr_(0.5)Mn_(0.5)O_(3)(LSCM)是一种因具有优良综合性能而受到广泛关注的固体氧化物电池(SOC)钙钛矿型燃料电极材料,但其在SOC工况下受Sr含量、温度、气氛等因素影响时的结构稳定性方面仍缺乏系统深入的研究。采用柠檬酸溶胶–凝胶法制备了不同Sr含量的LSCM粉体,对各样品在不同温度下还原处理后的晶体结构和晶型转变情况进行了XRD表征,发现经过还原热处理LSCM会发生菱方相和正交相之间的转变。详细探讨了LSCM的晶体结构随Sr含量和还原热处理温度变化的规律,并结合Fourier红外光谱和X射线光电子能谱表征以及第一性原理计算,从元素价态、金属—氧化学键强度、晶体结合能以及Jahn–Teller畸变等角度出发分析了Sr掺杂对体系结构稳定性的影响,阐明了与Sr含量及还原热处理温度相关的LSCM晶型转变机制。Introduction La_(1–x)Sr_(x)Cr_(0.5)Mn_(0.5)O_(3)(LSCM)perovskite as a SOC fuel electrode material has attracted much attention due to its excellent comprehensive performance.However,there is still a lack of systematic and in-depth research on the its structural stability that is affected by some factors such as Sr content,temperature,and atmosphere under operating conditions of SOC.In particular,previous work indicate that this material exhibits different electrode performances and crystal structures under Sr-free and Sr-containing conditions,having the Sr content impact on its structural stability and electrochemical performance.Therefore,this paper was to analyze the crystal structures of La_(1–x)Sr_(x)Cr_(0.5)Mn_(0.5)O_(3) heat-treated in a reducing atmosphere at elevated temperatures from 500℃to 1000℃.In addition,the mechanism of crystal structural transformation of LSCM in a high-temperature reducing atmosphere was also discussed.Methods The LSCM precursors with different Sr contents(i.e.,x of 0,0.1,0.2,and 0.3)were prepared by a citric acid sol-gel method.The precursors were calcined into LSCM powders in a muffle furnace at 1100℃.The LSCM powders were then thermally reduced in a reducing atmosphere at 500℃−1000℃.After reduction,the phase transformations of each sample were characterized by X-ray diffraction(XRD).The lattice constants of the samples were calculated based on the Rietveld method using a software named Rietica.In addition,the first-principles calculations,Fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS)were also performed to reveal the effects of Sr content and reduction heat treatment on the crystal transformation of LSCM.Results and discussion The samples with different Sr contents were calcined in air at 1100℃.A single trigonal phase appears when the Sr contents x≤0.2,while a small amount of SrCrO4 phase occurs besides the perovskite phase when x=0.3.After reduction at elevated temperatures,the sample with x of 0 transforms from a tr

关 键 词：固体氧化物电池 燃料电极 钙钛矿 相变 Jahn–Teller畸变 

分 类 号：TQ174.75[化学工程—陶瓷工业]