Factors affecting the permittivity of Gd-doped BaTiO₃

The permittivity of BaTiO 3 doped with small concentrations of Gd 2 O 3 (0.01 approximately 0.1 mol.%) are found to be remarkably dependent on the type of the solid solution formed between Gd 2 O 3 and BaTiO 3 . The decrease of permittivity at the Curie peak with decreasing grain size for BaTiO 3 doped with concentrations of Gd 2 O 3 from 0.5 approximately 3 mol.% is attributed to the formation of defective non-ferroelectric grain boundary layers of low permittivity.