The influence of in situ thermal treatment on electric properties of BaBi2Nb2O9 ceramics

The chemical composition as well as impedance spectroscopy were investigated for BaBi2Nb2O9 ceramics obtained by conventional mixed oxides method, before and after the sample was thermally treated (for 1 h) in an ultra-high vacuum (5 × 10−11 bar) at the temperature of 900 °C. The obtained results indicate the loss of stoichiometry as a result of applied thermal treatment, and lead to conclusion, that the chemical formula of the obtained material should be determined as BaBiNb2O9-x. The suggested formula emphasises the oxygen deficiency due to Bi–O saturated precipitate, along with lack of barium ions at the surface of the sample, and has major influence on material's electric properties.