Effect of Gd on dielectric and piezoelectric properties of lead zirconate titanate ferroelectric ceramics

ABSTRACT

In view of the importance of rare – earth modified PZT, Gd-modified lead zirconate titanate (PGZT) ceramics with a general chemical formula Pb_1-xGd_x(Zr_0.35Ti_0.65)_1-x/4O₃ (x = 0, 0.07,0.10,0.12) near morphotropic phase boundary (MPB) have been prepared using  high-temperature solid-state reaction route. The X-ray diffraction (XRD) study shows the formation of single phase rhombohedral structure for x $\le$ 0.07 and tetragonal structure for x > 0.07 at room temperature. Dielectric properties (ϵ_r and tanδ) were studied as a function of temperature (25–500°C) at different frequencies (1–1000 kHz) exhibit a systematic change in dielectric constant, phase transition temperature and diffusivity. Results of detailed dielectric study indicate the diffuse phase transition at higher value of gadolinium concentration and non-relaxor behavior. The ac conductivity spectrum of PGZT/x/35/65 ceramics is found to obey Jonscher's Universal power law. The appearance of hysteresis loops below transition temperature supports the existence of ferroelectric properties in the studied compounds. The enhancement of remnant polarization (P_r) and piezoelectric constants (d₃₃) was obtained with substitution of Gd for the PZT ceramics which can be used for multilayer capacitor, sensor and actuator applications.

KEYWORDS:

• PGZT
• XRD
• dielectric studies; non-relaxor
• ferroelectricty