Temperature stable K_0.5(Nd_1−xBi_x)_0.5MoO₄ microwave dielectrics ceramics with ultra-low sintering temperature

K_0.5(Nd_1−xBi_x)_0.5MoO₄ (0.2 ≤ x ≤ 0.7) ceramics were prepared via the solid-state reaction method. All ceramics densified below 720°C with a uniform microstructure. As x increased from 0.2 to 0.7, relative permittivity (ɛ_r) increased from 13.6 to 26.2 commensurate with an increase in temperature coefficient of resonant frequency (TCF) from – 31 ppm/°C to + 60 ppm/°C and a decrease in Qf value (Q = quality factor; f = resonant frequency) from 23 400 to 8620 GHz. Optimum TCF was obtained for x = 0.3 (−15 ppm/°C) and 0.4 (+4 ppm/°C) sintered at 660 and 620°C with ɛ_r ~15.4, Q_f ~19 650 GHz, and ɛ_r ~17.3, Q_f ~13 050 GHz, respectively. Ceramics in this novel solid solution are a candidate for ultra low temperature co-fired ceramic (ULTCC) technology.