Dielectric and Raman Spectroscopic Studies of Na_(0.5)Bi_(0.5)TiO_3-BaSnO_3 Ferroelectric System

摘要

A series of lead-free perovskite solid solutions of (1 - x) Na_(0.5)Bi_(0.5)TiO_3(NBT)-x BaSnO_3(BSN), for 0.0 ≤ x ≤ 0.15 have been synthesized using a high-temperature solid-state reaction route. The phase transition behaviors are studied using dielectric and Raman spectroscopic techniques. The ferroelectric to relaxor phase transition temperature (T_(FR)) and the temperature corresponding to maximum dielectric permittivity (T_m) are estimated from the temperature-dependent dielectric data. Dielectric studies show diffuse phase transition around ～335℃ in pure NBT and this transition temperature decreases with increase in x. The disappearance of x-dependence of A_1 mode frequency at ～134 cm~(-1) for x ≥ 0.1 is consistent with rhombohedral-orthorhombic transition. In situ temperature dependence Raman spectroscopic studies show disappearance and discontinuous changes in the phonon mode frequencies across rhombohedral (x ＜ 0.1)/orthorhombic (x ≥0.1) to tetragonal transition.