Dielectric and microstructural properties of barium titanate hafnate thin films

Barium titanate hafnate (BaTi1−xHfxO3, 0 ≤ x ≤ 0.25) thin films have been deposited by a chemical solution method on copper foil substrates. The films were crystallized at 900 °C and in a reducing atmosphere to prevent substrate oxidation. Perovskite phase formation was identified for each composition, accompanied by an increased pseudocubic lattice parameter. Temperature dependent dielectric measurements revealed a decreasing phase transition temperature and peak permittivity with increasing hafnium level. The decrease in permittivity resulted from grain size reduction with increasing hafnium content. Compositions containing 25 mol% barium hafnate display a deviation from Curie–Weiss behavior indicating the onset of relaxor behavior.