Phase evolution and dielectric properties of fluorite-type Bi₃(Nb_0.9M_0.1)O_7+δ ceramics (M=Ti, Zr, Sn, W, δ=±0.05)

Phase structure and dielectric behavior of Bi₃(Nb_0.9M_0.1)O_7+δ ceramics (M = Ti, Zr, Sn, W, δ = ±0.05) were discussed. Cubic fluorite solid solutions Bi₃(Nb_0.9M_0.1)O_7+δ (M = Zr, Sn, W, δ = ±0.05) were obtained through a conventional solid state reaction method. An analysis of the microwave dielectric properties showed that substitution of Nb⁵⁺ by W⁶⁺ was favorable to improving the temperature coefficient of resonant frequency (TCF value). A temperature stable dielectric material Bi₃(Nb_0.9W_0.1)O_7.05 was introduced. The Bi₃(Nb_0.9W_0.1)O_7.05 ceramics sintered at 930 °C for 2 h exhibited a high permittivity of 92.4, a Qf value of 260 GHz and a TCF value of −34 ppm/°C.