Investigation of Ba2-xSrxTiO4: Structural aspects and dielectric properties

Investigation of solid solution of barium-strontium orthotitanates of the type, Ba2-xSrxTiO4 (0 ≤x≤ 2), show that pure phases exist only for the end members, Ba2TiO4 and Sr2TiO4, crystallizing in the β-K2SO4 and K2NiF4 structures, respectively. The intermediate compositions (till≥ 1) lead to a biphasic mixture of two Ba2TiO4-type phases (probably through a spinodal decomposition) with decreasing lattice parameters, indicating Sr-substitution in both the phases. Forx > 1, Sr2TiO4 along with a secondary phase is obtained. The dielectric constant and dielectric loss were found to decrease with Sr substitution till the nominal composition ofx = 1. However, pure Sr2TiO4 shows higher dielectric constant compared to the solid solution composition. Sr2TiO4 shows very high temperature stability of the dielectric constant.