Relaxor behavior in lead-free Ba(Ti-1,Sc-x/Nb-2(x/2))O-3 ceramics

Solid solutions of (I-x)BaTiO3-xBaSc(1/2)Nb(1/2)O(3) (BT-BSN) with x=0.025, 0.05, 0.075, 0.1 and 0.125 were prepared by a high temperature solid-state reaction technique. The effects of the Ba(Sc1/2Nb1/2)O-3 addition on the phase composition, dielectric properties, as well as polarization-electric field (P-E) loops of the BT-BSN solid solution were investigated. The room-temperature X-ray diffraction analyses of all the ceramics revealed a perovskite phase after sintering at 1350 degrees C with a composition-dependent symmetry. Temperature and frequency dependence of the dielectric permittivity and losses have been explored: ceramics of compositions x <= 0.075 showed normal ferroelectric behavior, while ceramics with x >= 0.1 were of relaxor type. The degree of diffuseness and the relaxor effect increase while the transition temperature (T-c or T-O decreases when both scandium and niobium are introduced in the BaTiO3 lattice. Ceramics of composition x= 0.125 exhibited interesting relaxor characteristics at 10 kHz: Delta T-m = 20 K, epsilon(r) = 12,000, and T-m = 140 K. In addition, modeled using Vogel-Fuilcher relation, this same composition showed the fitting parameters: Ea = 0.0503 eV, f(0) = 1.129 x 10(14) Hz and T-vF =166.85 K. (C) 2014 The Ceramic Society of Japan and the Korean Ceramic Society. Production and hosting by Elsevier B.V. All rights reserved.