Phase composition, densification and electrical conductivity of Lasub(0.9)Srsub(0.1)Gasub(0.8)Mgsub(0.2)Osub(3-'delta') consolidated by the two-stage sintering method

Abstract

The influence of the method of sintering on densification, phase assemblage and electrical conductivity of Sr- and Mg-doped lanthanum gallate was investigated aiming to optimize the sintering process of this solid electrolyte. Powder mixtures were prepared by solid state reactions, and the sintering of green compacts was carried out by the two-stage method varying the temperature of the first stage (T1) and the isothermal temperature (T2) and time (t2) profile. The type and content of predominant impurity phases depend on specific parameters of the sintering process. In the first stage of sintering, the content of impurity phases, such as LaSrGaO4 and La4Ga2O9, decreases with increasing temperature. The relative density of sintered specimens reaches 99% whenever T1 is 1500 1C. The mean grain size varies from 1.45 to 4.9 mm. At 600 1C the electrical conductivity attains 12 mS cm 1 for T1 1400 1C and T2 1350 1C for 5 h, with activation energy of approximately 1 eV.