The microwave dielectric properties of CaTiO3–Li0.5Nd0.5TiO3 ceramics prepared with Bi2Ti2O7 additions

Ceramics of 0.4CaTiO3–0.6Li0.5Nd0.5TiO3 (0.4CT–0.6LNT) have been prepared by the mixed oxide route using additions of Bi2O3–2TiO2 (up to 30 wt.%). Powders were calcined 1100 °C; cylindrical specimens were fired at temperatures in the range 1175–1275 °C. Sintered products were typically 90–95% dense. The microstructures were dominated by angular grains typically 2 μm in size. With increasing levels of Bi2O3–2TiO2 additions, needle and then lath shaped second phases developed. Microwave dielectric properties of 0.4CT–0.6LNT at 2.1 GHz were 126, 2600 GHz and 127 ppm/°C for εr, Qxf and τf, respectively. The use of bismuth additions caused the relative permittivity to increase (to a maximum value of 150), the Qxf to steadily decrease (minimum value of 1000GHz) and τf to decrease almost linearly towards zero.