Ferroelectric and piezoelectric properties of lead-free BaTiO3 doped Bi0.5Na0.5TiO3 thin films from metal-organic solution deposition

Lead-free 0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3) (BNT-BT) piezoelectric thin films were prepared by metalorganic solution deposition onto a Pt/Ti/SiO2/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700 degrees C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 mu C/cm(2) with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 x 10(-4) A/cm(2) at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d(33)) of the BNT-BT thin film was approximately 51.6 pm/V. (C) 2012 Elsevier B.V. All rights reserved.