Relaxor ferroelectric properties of the (1–2x)BiScO3 · xPbTiO3 · xPbMg1/3Nb2/3O3 (0.30 ≤ x ≤ 0.46) system

Resumo

X-ray diffraction, dielectric, piezoelectric, and pyroelectric studies have been performed on ceramic samples of (1–2x)BiScO₃ · xPbTiO₃ · xPbMg_1/3Nb_2/3O₃ (0.30 ≤ x ≤ 0.46) perovskite-like solid solutions. The solid solution symmetry was found to vary from the rhombohedral (x ≤ 0.38) to tetragonal (x ≥ 0.42) as x increases. The samples with 0.30 < x ≤ 0.42 have properties characteristic of relaxor ferroelectrics, namely the existence of a wide peak in the temperature dependence of the dielectric permittivity at T_mε = 390–440 K that shifts to higher temperatures as the frequency increases, narrow unsaturated dielectric hysteresis loops, and an electric field-induced transition to the ferroelectric state at 318 K. The observed features of the dielectric, piezo-, and pyroelectric properties of these solid solutions are explained by the fact that they are relaxor ferroelectrics.