Structural and ferroelectric properties of spray deposited sodium nitrite:poly(vinyl alcohol) composite films

Abstract

The composite films of sodium nitrite (NaNO2) and poly(vinyl alcohol) (PVA) have been deposited by spray technique at different substrate temperatures. The x-ray diffraction study revealed structural distortion (b/a ratio) in the composite films. The field-emission scanning electron microscopy images suggest that PVA polymer facilitate the homogeneous distribution of spherical grains of NaNO2 with less porosity. The grain size is found to increase with the deposition temperature. The study of hysteresis loop characteristics gave optimum Pr at deposition temperature of 200 °C, which may be due to large structural distortion and less porosity. The back switching calculations and the switching characteristics indicate that 180° domains contribute more in the composite than the pure NaNO2 film. The 1/ϵ0(dP/dE)-E curves exhibit two coercive fields correspond to 180° and 90° domains. The composite film also showed improved fatigue characteristics.