Evaluation of Structural and Ferroelectric Properties in Spray Deposited (NH_4)_(0.39)K_(0.61)NO_3: Poly(vinyl alcohol) Composite Films

摘要

The composite films of (NH_4)_(0.39)K_(0.61)NO_3 (NKN)-poly(vinyl alcohol) (PVA) containing equal proportions of NKN and PVA have been prepared at different substrate temperatures, T_s (130-250 ℃) using spray deposition set up. The structural, phase stability, capacitance-voltage and ferroelectric properties of spray deposited NKN: PVA composite films were presented in this paper. Ferroelectric hysteresis loops were traced at room temperature for the composite films using modified Sawyer and Tower circuit. The remanent polarization (P_r) was found to be maximum in the composite films deposited on the substrate at 170 ℃. The stability of the P_r in the composite films exhibits improved fatigue compared with pure NKN films. The capacitance shows a strong bias dependence and exhibit nonlinear behavior. The X-ray diffraction studies confirm the existence of ferroelectric phase in these composite films. The atomic force microscopy images show that the composite films have uniform dispersion of NKN particles in the PVA matrix.