| 摘 要： | Single-phase La_(2–x)Nd_xMo_2O_9(0≤x≤1.8) compounds were prepared using solid-state reaction technique. Their structural and thermal p roperties were characterized by room and high temperatures X-ray diffraction(XRD), thermo gravimetric analysis-differential scanningcalorimetry(TG-DSC), and high temperature Raman spectra. The transport properties were investigated using D.C. four-probe technique and Hebb-Wagner polarization method. The substitution limit of Nb~(3+) in La_(2–x)Nd_xMo_2O_9 was determined to be in the range of 1.8x1.9, and the cubic lattice parameter of La_(2–x)Nd_xMo_2O_9 decreased linearly with the increasing of x. When the Nb~(3+) substitution content x was larger than 0.6, the α/β phase transition could be depressed to such a great degree that the phase transition thermal enthalpy was not detected by DSC. The temperature dependence of electrical conductivities for La_(1.4)Nd_xMo_2O_9 below 873 K and that for LaNdMo_2O_9 below 923 K obeyed the Arrhenius law, while above 873 and 923 K Vogel-Tammann-Fulcher(VTF) model could describe the conduction behaviors satisfactorily. The transition of transport mechanism from Arrhenius to VTF was caused by the change of structure, which was supported by the high temperature XRD and Raman results. The ionic transport number of La_(1.4)Nd_xMo_2O_9 in air was larger than 0.99 at 1073 K, and with the increasing of temperature it was close to 0.98 at 1173 K. In view of the phase transition, thermal expansion and conductivity properties, La_(1.4)Nd_xMo_2O_9 should be a promising electrolyte material in La_(2–x)Nd_xMo_2O_9 series.
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