Influence of La doping concentration and A-site deficiency on electrical conductivity of La substituted SrTiO3 and its chemical compatibility with ScSZ

Abstract

The influence of La doping concentration and A-site deficiency concentration on the electrical conductivity of La substituted SrTiO3 and its high-temperature chemical compatibility with ScSZ was investigated. It was found that the chemical compatibility between (LaxSr1-x)1-yTiO3-δ ((LxS1-x)1-yT) and 1CeO2-10Sc2O3–89ZrO2 (ScSZ) gradually deteriorates with the increase of La doping concentration from 10% to 40%. When the La doping concentration is 30–40%, chemical reaction will occur between LxS1-xT and ScSZ and La2Zr2O7 (LZO) will be generated, and the diffusion of Sc3+and Zr4+ in ScSZ to LxS1-xT is aggravated. A-site deficient (LxS1-x)1-yT can effectively inhibit the interfacial reaction and element interdiffusion between it and ScSZ. The first principle computation results indicate that the influence of La doping concentration and A-site deficiency on the vacancy formation energy (VFE) of Ti in (LxS1-x)1-yT determines its chemical compatibility with ScSZ. The results of electrical conductivity test and the first principle computation indicate that the La doping concentration and A-site deficiency will simultaneously influence the amount of Ti4+ to Ti3+ and the oxygen vacancy concentration in (LxS1-x)1-yT in reducing atmosphere, thus affecting its conductivity.