Ferroelectric Properties of (Na0.5K0.5)NbO3–BaZrO3–(Bi0.5Li0.5)TiO3 Thin Films Deposited on Pt/(001)MgO Substrate by Pulsed Laser Deposition

Abstract

0.92(Na0.5K0.5)NbO3–0.06BaZrO3–0.02(Bi0.5Li0.5)TiO3 (NKN–BZ–BLT) thin films with a thickness of about 2.0 µm were fabricated on a Pt/(001)MgO substrate by pulsed laser deposition (PLD). The X-ray diffraction pattern (XRD) showed that the NKN–BZ–BLT thin films that were oriented in both the 001pt and the 101pt directions [determined by pseudo-tetragonal perovskite (pt)] were grown on the Pt/(001)MgO substrate. A rocking curve measurement revealed that the fluctuations of the crystalline orientation of the 001pt- and 101pt-oriented NKN–BZ–BLT grains are very small. The reciprocal space map and pole figure showed that the 001pt-oriented NKN–BZ–BLT grains epitaxially grew on the Pt/(001)MgO substrate. On the other hand, the 010pt axis (existing in the in-plane) of the 101pt-oriented NKN–BZ–BLT grains rotated by 45° for the 100 axis (existing in the in-plane) of the (001)MgO substrate. The dielectric constant εr and the dielectric loss tan δ of the NKN–BZ–BLT thin films were 682 and 0.076 at 1 kHz, respectively. The P–E hysteresis loops of the NKN–BZ–BLT thin films showed clear ferroelectricity. The remanent polarization Pr and coercive electric field Ec were 24.5 µC/cm2 and 29.3 kV/cm, respectively. The NKN–BZ–BLT thin films exhibited larger Pr values than NKN–BZ–BLT ceramics.