稀土离子半径对稀土锆酸盐的组织结构和电学性能的影响

Effect of rare-earth ionic radius on microstructure and electrical property of rare-earth zirconate ceramics

摘要:

采用X射线衍射、高分辨透射电镜、选区电子衍射、拉曼光谱以及阻抗谱等手段研究了稀土锆酸盐（A2Zr2O7）材料的晶体结构和电学性能，发现稀土锆酸盐A2Zr2O7的有序度随稀土阳离子半径的减小逐渐降低。Sm2Zr2O7和Eu2Zr2O7陶瓷为有序的烧绿石相，而Gd2Zr2O7和Dy2Zr2O7为无序的缺陷型萤石相。与其它几种稀土锆酸盐的电导率相比，有序度相对较低的烧绿石相Eu2Zr2O7具有最大的晶粒电导率(1.03?10–2S?cm–1, 1173K)。

Abstract:

The microstructure and electrical conductivity of A2Zr2O7 ceramic have been investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) coupled with selected area electron diffraction (SAED), Raman spectroscopy and Impedance spectroscopy. The results show that the degree of structural order of rare-earth zirconates A2Zr2O7 ceramics gradually decreases with decreasing ionic radius of rare-earth cations. The Sm2Zr2O7 and Eu2Zr2O7 ceramics exhibit an ordered pyrochlore phase, while Gd2Zr2O7 and Dy2Zr2O7 ceramics have a disordered fluorite phase. Pyrochlore-type Eu2Zr2O7 ceramic with a relatively low structural order degree shows the maximum grain conductivity of 1.03?10–2S?cm–1 at 1173K, as compared with that of the other rare-earth zirconates.