Low-temperature synthesis and characterization of lead zinc niobate thick films

Perovskite Pb(Zn_1/3Nb_2/3)O₃ (PZN) thick films were prepared by a hydrothermal route at a low temperature (150°C) on Ti metal, where the titanium (Ti) metal served as both the substrate and bottom electrode for the PZN films. The thickness of the PZN film fabricated on the Ti substrate was about 20 μm. We have demonstrated that the concentration of KOH plays a key role in obtaining the perovskite structure in the PZN film. The dielectric relaxation was studied as a function of temperature and frequency. A dispersion of the maximum dielectric permittivity (ε_max) appears around the temperature of T_m, which shifts toward higher temperatures with increasing frequency. The variation of T_m with frequency follows the Vogel-Fulcher relationship. The variation of 1/ε with temperature above T_m deviates from the Curie-Weiss (CW) law but satisfies the modified CW law. The relaxation indication coefficient (γ) and broadening parameter (Δ) were estimated from a quadratic fit of the modified Curie-Weiss law and were found to be 2.00 and 42 K, respectively, indicating strong relaxor behavior. The samples showed excellent reproducibility in the measurements of leakage current, a remnant polarization of 14 μC/cm², and a coercive field of 300 kV/m.