Structural and electrical properties of La2-xSrxMo2O9-δ

• Published in: Journal of rare earths Vol. 31; no. 4; pp. 428 - 434
• Main Author: 闫柏军 李明 张家芸
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2013
• Subjects: Argon; Atmospheres; Conductivity; Dopants; Electronics; impedance spectroscopy; inorganic compounds; ionic conduction; La2Mo2O9; Polarization; Rare earth metals; rare earths; Strontium; X-ray diffraction; 化学计量系数; 电子电导率; 电气性能; 离子迁移数; 空气气氛; 立方结构; 锶掺杂; X-ray diffraction; impedance spectroscopy; ionic conduction; inorganic compounds; rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/S1002-0721(12)60299-3

Sr-doped La2Mo2O9 were prepared by solid state reaction and characterized by XRD, impedance spectroscopy and Hebb- Wagner polarization method. XRD patterns of the samples indicated that the solubility limit of Sr2＋ in La2-xSrxM02O9 -δ was in the range of 7 mol.% to 7.5 tool.%, i.e., the maximum stoichiometric coefficient x in La2~SrxMo209_a was larger than 0.14 and less than 0.15. The cubic lattice parameter of La2 xSrxM02Og-δ （0〈x〈4） increased linearly with the content of dopant Sr2＋ increasing and the relationship could be expressed as： a=0.7154＋0.0045 lx （ram）. The total conductivities of Sr-doped La2M0209 were measured by im- pedance spectroscopy method in argon and air atmosphere, respectively. The results indicated that substituting Sr2＋ fbr La3＋ could suppress the first order phase transform ofLa2M02O9 and stabilize the cubic structure to room temperature, and tile conductivities of Sr-doped La2M02O9 were more sensitive to the change of atmosphere than that of undoped La2M02O9. The conductivity variation of Sr-doped La2M02O9 with the dopant content exhibited similar trend in air and argon atmosphere, firstly decreased and then increased with the dopant content increasing, and a minimum value appeared at x=0.1. The electronic conductivities of Sr-doped La2M02O9 were measured using Hebb-Wagner polarization method in argon atmosphere. It could be found that Sr-doping caused the increase in electronic conductivity and decrease in oxide-ion transport numbers, but the conducting species were predominantly oxide ions. And the oxide-ion transport numbers of some St-doped La2Mo2O9 samples could also reach 0.99.