Structure and dielectric properties of a new tantalate Ba3TiTa4O15

A tantalate Ba3TiTa4O15 was synthesized by doping Ti4+ in the binary system BaO-Ta2O5. The crystal structure was determined by X-ray powder diffraction, and it belongs to paraelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters : a = 1.256 27(6)nm, c = 0.395 86(4) nm. Dielectric measurements showed that the phase transition of Ba3TiTa4O15 from ferroelectric to paraelectric occurred at -35 degreesC, lower than that of Ba6Ti2Nb8O30. The dielectric constant of Ba3TiTa4O15 ceramic was stable at room temperature with the frequency increasing from I kHz to 1 MHz, while the dielectric loss was as low as 0.002. Ba3TiTa4O15 might be a suitable candidate for microwave dielectric ceramics.