Ceramics-Silikáty 47 (1) 8-12 (2003)

MICROSTRUCTURE AND ELECTRICAL RESPONSE OF 0.9Pb(Mg_1/3Nb_2/3)O₃-0.1PbTiO₃ RELAXOR CERAMICS

V. Kovaľ, J. Briančin

Ceramic samples of a solid solution of 10 mol.% lead titanate PbTiO₃ (PT) in lead magnesium niobate Pb(Mg_1/3Nb_2/3)O₃ (PMN) were investigated from the view-point of phase transition behavior and electrical properties. Dielectric spectroscopy in a frequency region of 102 - 106 Hz was carried out to study the temperature and frequency dependence of the weak-field dielectric response in 0.9PMN-0.1PT material prepared via a columbite precursor route. The temperature T_m of the observed maxima in the dielectric permittivity (e_m) was found to shift from 45.4 to 58.5°C and e_m decreased from 4500 to 4060 as the frequency increased from 100 Hz to 1 MHz. The characteristics of a diffuse phase transition (DPT) behavior (g » 1.8 and d_g » 30°C) were determined using an extended Curie-Weiss law. The relaxor features of ferroelectrics were also demonstrated by a "slim" ferro-electric hysteresis loop. Non-zero values of the piezoelectric parameters (k^p » 1.6 %, d₃₁ » -3.6 pC/N) and spontaneous polari-zation (Ps » 2.4 µC/cm2) were observed at 80°C, indicating the existence of nanopolar regions in the structure far above the T_m.

Keywords: PMN-PT, Dielectric, Piezoelectric, Ferroelectric properties, Diffuse phase transition