Growth and properties of highly oriented lead-free Mn-doped NaNbO3–BaTiO3 piezoelectric thin films prepared by chemical solution deposition

Abstract

Highly oriented lead-free piezoelectric NaNbO3–BaTiO3 (NN–BT) thin films have been fabricated by a chemical solution deposition method. Alkoxy-derived 1.0 and 3.0mol% Mn-doped 0.95NaNbO3–0.05BaTiO3 thin films directly crystallized into a perovskite phase with a (100) preferred orientation on Pt(100)/MgO(100) substrates at 650°C. The three-dimensional relationship between NN–BT(100) and Pt(100)/MgO(100) is confirmed by the fourfold symmetry of the pole figure. The fourfold symmetry indicates that synthesized films are oriented in both the c and a, b directions on the Pt(100) surface. The (100)-oriented Mn-doped 0.95NaNbO3–0.05BaTiO3 thin films showed typical ferroelectric polarization (P)–electric field (E) hysteresis and field-induced displacement curves at room temperature. The remanent polarization and coercive field values of the oriented 1.0 and 3.0mol% Mn-doped 0.95NaNbO3–0.05BaTiO3 films were 10.4, 11.6μC/cm2 and 62, 54kV/cm, respectively. Furthermore, from the slope of the field-induced butterfly loop characterized using a scanning probe microscopy, the effective piezoelectric coefficient (AFM-d33) of the films was found to be approximately 35–50pm/V.