镱掺杂的Ca1-xYbxMnO3(x=0～0.2)化合物的Rietveld结构精修和热电性能  

Rietveld Refinement and Thermoelectric Properties of Ytterbium Doped Ca_(1-x)Yb_xMnO_3(x=0～0.2) Compounds

作　　者：路清梅[1] 张冰心[1] 张飞鹏[1] 张忻[1] 张久兴[1] 

机构地区：[1]北京工业大学材料科学与工程学院,新型功能材料教育部重点实验室,北京100124

出　　处：《中国稀土学报》2010年第4期471-477,共7页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金(50702003);北京市教委科技发展计划资助项目

摘　　要：采用溶胶-凝胶和无压烧结的方法制备了Yb掺杂的钙钛矿型Ca1-xYbxMnO3（x=0~0.2）系列固溶体,并结合X射线R ietveld精修、扫描电子显微镜及热电性能测试,系统研究了Yb掺杂量对产物相组成、晶体结构、显微结构和热电性能的影响。结果表明,Yb的掺杂引起了CaMnO3的晶格畸变,导致Mn-O2-Mn键角（氧八面体在水平方向的扭转）随着Yb的增加而减小;Yb的掺杂大幅度降低了样品的电阻率,并改变了电传输特性：Seebeck系数绝对值显著降低,同时随着掺杂量的增加,进一步减小。Yb的掺杂明显抑制了晶粒长大,此外,其重原子特性和少量第二相的生成显著降低了材料的热导率。其中x=0.1的样品Ca0.9Yb0.1MnO3在T=700℃时,ZT值达到0.093,较单相的CaMnO3提高了120%。A series of Yb-substituted Ca1-xYbxMnO3（x=0~0.2） solutions with perovskite structure were synthesized via sol-gel and non-pressure sintering method,and the influence of Yb-doping on phase,crystal structure,microstructure and thermoelectric performance were investigated systematically based on X-ray Rietveld refinement,SEM,and thermoelectric properties measuring system.The refinement showed that the Yb-substitution for Ca site led to lattice distortion of CaMnO3,and so the Mn-O2-Mn angles（distortion of oxygen-octahedron parallel to ac plane） decreased with increasing content of Yb.Substituting the Ca site with rare earth Yb caused a strong decrease of resistivity and changed the transport characteristic;Seebeck coefficient value decreased with further doping of Yb.In addition,Yb-substitution restrained grain growth and its larger mass and secondary phase decreased thermal conductivity.As a result,ZT value of sample with x=0.1 reached its peak of 0.093 at 700 K which was about 120% higher than CaMnO3.

关 键 词：钙钛矿 掺杂 RIETVELD精修 热电性能 稀土 

分 类 号：O649[理学—物理化学]