Effects of the substitution of titanium by iron and niobium on the structure and dielectric properties in BaTi1-x(Fe0.5Nb0.5)xO3 solid solution

Polycrystalline samples of BaTi1-x(Fe0.5Nb0.5)(x)O-3 with x = 0.025, 0.05, 0.075, 0.1, 0.125 and 0. 15 have been synthesized by high-temperature solid-state reaction technique. The effects of cationic substitution of iron and niobium for titanium in the B sites for BaTiO3 perovskite lattice on symmetry and dielectric properties were investigated. X-ray diffraction at room temperature and dielectric permittivity in the temperature range from 85 to 500 K with frequencies range from 10(3) to 2 x 10(5) Hz, respectively, were studied. The evolution from a normal ferroelectric to a relaxor ferroelectric is emphasized. T-C or T-m decreases when both iron and niobium are introduced in the lattice of BaTiO3. A high dielectric constant of around 30,000 at T-C = 280 K was found for BaTi0.925(Fe0.5Nb0.5)(0.075)O-3 ceramic. A relaxor ferroelectric with Delta T-m = 12 K and epsilon'(r) about 13,800 at 10 kHz with T-m = 186 K was found for BaTi0.875 (Fe0.5Nb0.5)(0.125)O-3 sample. (c) 2006 Elsevier B.V. All rights reserved.