The Preparation of Pure and Phosphrous-Doped La<sub>2</sub>Mo<sub>2</sub>O<sub>9</sub> Oxide Ion Conductor by a Modified Precipitation Method

Abstract

Lanthanum molybdate, La2Mo2O9, has been attracted considerable attention owing to its high concentration of intrinsic oxygen vacancies. In this paper, pure and phosphrous-doped La2Mo2O9 (LAMOX) is prepared by means of a modified precipitation method. The properties of the series of compounds have been characterized by thermal analysis (TGA-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and conductivity measured by a.c. impedance spectroscopy (IS). The electrical conductivity of pure La2Mo2O9 prepared by this method reaches a value of 0.15 S/cm at 800 °C, much higher than that of the sol-gel prepared material. P-doped La2Mo2O9 underwent a slightly structural phase transition, and the transition temperature is found to decrease with increasing P content. Electrical conductivity measurements show a slightly increase in the conductivity at low temperature after the tiny doping of P.