Ferroelectric Properties of (Na0.5K0.5)NbO3-Based Thin Films Deposited on Pt/(001)MgO Substrate by Pulsed Laser Deposition with NaNbO3 Buffer Layer

Abstract

(Na0.52K0.44Li0.04)(Nb0.84Ta0.10Sb0.06)O3 (NKLNTS) thin films with a thickness of about 1.4 µm were fabricated on Pt/(001)MgO substrate, on which an NaNbO3 buffer layer was introduced, by pulsed laser deposition (PLD). The X-ray diffraction pattern (XRD) showed that the 001 orientated NKLNTS thin films were grown on Pt/(001)MgO substrate. A rocking curve measurement revealed that the fluctuation of the crystalline orientation of the 001 orientated NKLNTS thin films is very small. The lattice parameters of the 001 orientated NKLNTS thin films were a=0.3911 nm and c = 0.3942 nm, determined by reciprocal space map. The dielectric constant, εr, and the dielectric loss, tan δ, of the NKLNTS thin film were 398 and 0.22 at 1 kHz, respectively. The large tan δ is due to NKLNTS having a morphotropic phase boundary region around room temperature. The P–E hysteresis loops of the NKLNTS thin films showed clear ferroelectricity. The remanent polarization, Pr, and coercive electric field, Ec, were 26.3 µC/cm2 and 28.6 kV/cm, respectively. The NKLNTS thin films exhibited larger Pr value than NKLNTS ceramic.