A study on the structural and electrical properties of lanthanum-doped strontium titanate prepared in air

In this study, La-doped SrTiO3 specimens were prepared in air, and the structural and electrical properties were studied. The lattice parameter of the Sr1-xLaxTiO3, which was sintered at 1723-1923 K in air, increased proportionally with increasing x. This proportionality relation agreed with a Vegard's law between SrTiO3 and LaTiO3. As a result of comparison with other literature data, it was proved that the lattice parameter in Sr1-xLaxTiO3 is highly dependent on the condition of sample preparation. Sr0.9La0.1TiO3 displayed a remarkable hysteresis in the temperature dependence of the conductivity under reducing atmospheres. On the other hand, Sr0.7La0.3TiO3 showed very low dependence of the conductivity on temperature and PO2. It is considered that the presence of point defect clustering and/or Ruddlesden-Popper phase in highly La-doped SrTiO3 specimens blocked the rapid diffusion of oxygen and electronic conduction between titanium ions.