The Effect of Al Doping on Ferroelectric and Dielectric Properties of PLZT Transparent Electro-optical Ceramics

The PLZT (8.0/69/31) transparent ceramics with Al doping were prepared by hot-press sintering technique. A single perovskite structure was observed by X-ray diffraction in all samples. The ferroelectric and dielectric properties of the materials change obviously with increasing Al content: The maximum dielectric constant was raised to 16,000, while the dielectric constant (er) at room temperature presented a decreasing tendency from 5764 to 2501. The polarization versus electric field (P-E) hysteresis loops change from antiferroelectric (AFE) phase to ferroelectric (FE) phase at room temperature. The grains of the PLZT ceramics grow up with less Al doping, but the grain size decreases, while the Al-doping content increases further. The PLZT ceramics with a little Al (x = 0.50 mol%) doping exhibit a better transparency and conspicuous variations in ferroelectric and dielectric properties. This will be helpful for designing the materials for optical modulators.