Bi系Co基氧化物热电材料制备及结构替代研究

Preparation and Structure Alternatives of Bismuth Cobalt Oxide Thermoelectric Materials

采用常压固相烧结法制备B i2SrCaCo2Oδ和B i2Ca2Co2Oδ氧化物热电材料,研究Sr、Ca位替代或掺杂对陶瓷材料制备条件、晶体结构和电学性能的影响。通过XRD、SEM、EDS等表征技术及标准四探针法研究了烧结温度和晶体结构参数对陶瓷物相、显微组织形貌和电学性能的影响。结果表明同族元素Ca、Sr的互相替代,B i系Co基氧化物仍然呈现岩盐型层片状晶体结构,且一定程度上表现出插层替代的特性,仍具有明显的c轴择优取向。由于Ca元素替代Sr元素,c轴尺寸减小,同时烧结温度上升;电阻率-温度关系图显示,样品呈现出明显的半导体特性。

Bi2SrCaCo2Oδ and Bi2Ca2Co2Oδ oxide thermoelectric materials were prepared by solid-state reactions.The effect of substitution Ca for Sr on ceramic preparation condition,electrical properties and crystal structure anisotropic were studied.Influence of sintering temperatures and doping content on microstructure as well as electrical properties of ceramics were investigated by XRD,SEM and a standard four probes method.The results indicate that the crystal structure of Bi2Sr2Co2Oδ is not destroyed by Ca substitution on the Sr,and also shows layered grown obviously,c-axis preferred orientation obviously.The c-axis size decreased due to the replacement of Sr with Ca.The sintering temperatures increase with the substitution Ca for Sr.Temperature dependence of electric resistivity showed obviously semiconductive behaviors.