Effect of Al doping on structural and dielectric properties of PLZT ceramics

Polycrystalline samples of Al modified lead lanthanum zirconate titanate [PLZT] with Zr = 55% and Ti = 45%, have been synthesized by a high-temperature solid-state reaction technique. X-ray diffraction analysis of the compounds suggests the formation of a single-phase compound with tetragonal structure. Dielectric studies of the compounds as a function of temperature (from 30 to 350°C) at frequency (1, 10 and 100 kHz) show that the compounds undergo a phase transition of diffuse type.The transition temperature shifts towards higher side with increase in frequency a typical characteristic of a relaxor material. Diffusivity (γ) study of phase transition of these compounds provided its value between 1 and 2, indicating the variation of degree of disordering in the system. Measurement of dc resistivity (ρ) as a function of temperature (Room temperature, RT to 350°C) at a constant biasing field suggests the compounds have negative temperature coefficient of resistance (NTCR).