Ferroelectric and structural properties of Ba2−xSrxNaNb5O15 thin films prepared on La0.05Sr0.95TiO3 substrates

The Sr-substituted Ba2NaNb5O15 (Ba2-xSrxNaNb5O15) thin films were prepared on the La0.05Sr0.95TiO3 substrates by pulsed laser deposition. When the substrate temperature was fixed at 700 degrees C, the thin films exhibited highly c-axis orientation and smooth surface. The c-axis orientation and surface roughness do not depend much on Sr concentration. These thin films consisted of small grains with a diameter of 50-80 nm against the film thickness of 400 nm. The postannealed Ba2-xSrxNaNb5O15 thin films exhibited good P-E hysteresis loops. The remanent polarization (P-r) and coercive field (E-c) at x=1.4 were 2P(r)=59.4 mu C/cm(2) and 2E(c)=182.0 kV/cm, respectively. Its leakage current was 4.0 x 10(-7) A/cm(2). The low leakage current contributes to the increase in band gap with Sr substitution. (c) 2008 American Institute of Physics.