Preparation of (0 2 0)-oriented BaTi2O5 thick films and their dielectric responses

Barium dititanate (BaTi2O5) thick films were prepared on a Pt-coated Si substrate by laser chemical vapor deposition, and ac electric responses of (0 2 0)-oriented BaTi2O5 films were investigated using several equivalent electric circuit models. BaTi2O5 films in a single phase were obtained at a Ti/Ba molar ratio (mTi/Ba) of 1.72–1.74 and deposition temperature (Tdep) of 908–1065 K as well as mTi/Ba = 1.95 and Tdep = 914–953 K. (0 2 0)-oriented BaTi2O5 films were obtained at mTi/Ba = 1.72–1.74 and Tdep = 989–1051 K. BaTi2O5 films had columnar grains, and the deposition rate reached 93 μm h−1. The maximum relative permittivity of the (0 2 0)-oriented BaTi2O5 film prepared at Tdep = 989 K was 653 at 759 K. The model of an equivalent circuit involving a parallel combination of a resistor, a capacitor, and a constant phase element well fitted the frequency dependence of the interrelated ac electrical responses of the impedance, electric modulus, and admittance of (0 2 0)-oriented BaTi2O5 films.