Phase evolution and dielectric properties of fluorite-type Bi3(Nb0.9M0.1)O7+δ ceramics (M=Ti, Zr, Sn, W, δ=±0.05)

• The Bi3(Nb0.9M0.1)O7+δ ceramics (M = Ti, Zr, Sn, W, δ = ±0.05) with fluorite structure were obtained.
• The Bi3(Nb0.9W0.1)O7.05ceramic was a new temperature stable LTCC material.
• The firing temperature of the Bi3(Nb0.9W0.1)O7.05 ceramic was 930 °C.
• Bi3(Nb0.9W0.1)O7.05 ceramic possessed a permittivity ∼92.4, a Qf value ∼260 GHz and a TCF value ∼ −34 ppm/°C.

Phase structure and dielectric behavior of Bi3(Nb0.9M0.1)O7+δ ceramics (M = Ti, Zr, Sn, W, δ = ±0.05) were discussed. Cubic fluorite solid solutions Bi3(Nb0.9M0.1)O7+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(Nb0.9W0.1)O7.05 was introduced. The Bi3(Nb0.9W0.1)O7.05 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.