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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%。
Yb-doped perovskite-type Ca1-xYbxMnO3 (x = 0 ~ 0.2) solid solutions were prepared by sol-gel and pressureless sintering. In combination with X-ray Rietveld refinement, scanning electron microscopy and thermoelectric properties The effects of Yb doping amount on the phase composition, crystal structure, microstructure and thermoelectric properties of the product were systematically investigated. The results show that the doping of Yb causes the lattice distortion of CaMnO3, which leads to the decrease of the Mn-O2-Mn bond angle (the horizontal direction of the oxygen octahedron) decreases with the increase of Yb. The Yb doping decreases greatly The resistivity of the sample changes the electrical transmission characteristics: the absolute value of the Seebeck coefficient decreases significantly, and decreases further as the amount of doping increases. Yb doping significantly inhibited the grain growth, in addition, its heavy atomic properties and the formation of a small amount of second phase significantly reduces the thermal conductivity of the material. In the sample Ca0.9Yb0.1MnO3 with x = 0.1, the value of ZT reaches 0.093 at T = 700 ℃, which is 120% higher than that of single-phase CaMnO3.