Ferroelectric properties of NaNbO3-BaTiO3 thin films deposited on SrRuO3/(001)SrTiO3 substrate by pulsed laser deposition

Abstract

(NaNbO3)1-x(BaTiO3)x (NN-xBT) thin films with low BaTiO3 (BT) concentrations x (x = 0.05 and 0.10) were fabricated on SrRuO3/(001)SrTiO3 (SRO/(001)STO) substrate by pulsed laser deposition (PLD). X-ray diffraction pattern (XRD) and transmission electron diffraction pattern (TED) showed that NN-0.10BT thin film was epitaxially grown on SRO/(001)STO substrate with a crystallographic relationship of [001]NN-xBT||[001]STO. From reciprocal space maps, the lattice parameters of the out-of-plane direction of NN-xBT thin films became larger with an increase in BT concentration, although the lattice parameter of the in-plane was hardly changed by the BT concentration. The value of relative dielectric constant er of the NN-xBT thin films were increased with BT concentration. The er and the dielectric loss tanδ of NN-0.10BT were 1220 and 0.02 at 1 kHz, respectively. The P-E hysteresis loops of the NN-xBT thin films showed clear ferroelectricity. Although the value of remanent polarization Pr decreased with the BT concentration, the behaviors of er, Pr, and coercive electric field Ec of the NN-xBT thin films against the BT concentration accorded with those of NN-xBT ceramics, in which NN-0.10BT ceramics exhibited the largest piezoelectric property. Therefore, the NN-0.10BT thin film is expected to show high piezoelectricity.