Preparation of polycrystalline BaTi2O5 by pressureless sintering

Polycrystalline BaTi2O5 (BT2) was prepared by pressureless sintering in air using BaCO3 and TiO2 as starting materials. XRD results of the calcined powder showed BaCO3 and TiO2 reacted completely after being calcined above 950 °C, showing a mixture of BaTiO3 (BT), BT2, BaTi4O9 and Ba4Ti13O30. A small amount of ZrO2 (less than 0.1 wt%) was effective to prepare BT2 in a single phase and the second phase of BT and B6T17 increased with ZrO2 content. BT2 sintered body in a single phase was obtained at 1175–1300 °C when ZrO2 content was 0.08 wt%. The maximum permittivity of BT2 sintered body was 340 at the Curie temperature (Tc) of 463 °C and the frequency of 100 kHz.