Ferroelectric phase transition and optical performance of PLZnNZT transparent ceramics

Lead-based Pb0.97La0.02(Zn1/3Nb2/3)0.3(Zr0.53Ti0.47)0.7O3 (PLZnNZT) transparent ceramics with the addition of 2 wt% excess PbO were prepared by hot-pressing sintering method. The hot-pressing sintered PLZnNZT ceramics exhibit dense and large-grained microstructure, and perovskite structure with distorted cubic-like symmetry. The ceramics exhibit normal ferroelectric-like dielectric behavior with slightly diffused ferroelectric phase transition characteristic. The PLZnNZT ceramics exhibit fully developed, symmetric and saturated P-E hysteresis loop and large piezoelectric constant d33, being 468 pC/N. The ceramics with 120 μm thickness exhibit maximum transmittance of 53% at 850 nm when Fresnel losses was not included, almost totally transparent in the mid IR region (2500-5600 nm), and low-lying optical band gap energy Eg of 3.23 eV. Three diffused Raman bands centering around 240 cm−1, 560 cm−1 and 750 cm−1 are observed by micro-Raman spectroscopy, which can be attributed to F2g [BO6] bending vibration, A1g [BO6] stretching vibration and “soft mode” mixed by the bending and stretching vibrations, respectively, confirming the normal ferroelectric-like characteristic.