Phase evolution and microwave dielectric properties of (Li _0.5Bi_0.5)(W_1-xMo_x)O₄ (0.0 ≤ x ≤ 1.0) ceramics with ultra-low sintering temperatures

The (Li_0.5Bi_0.5)(W_1-xMo_x)O ₄ (0.0 ≤ x ≤ 1.0) ceramics were prepared via the solid state reaction method. The sintering temperature decreased almost linearly from 755°C for (Li_0.5Bi_0.5)WO₄ to 560°C for (Li_0.5Bi_0.5)MoO₄. When the x≤0.3, a wolframite solid solution can be formed. For x = 0.4 and x = 0.6 compositions, both the wolframite and scheelite phases can be formed from the X-ray diffraction analysis, while two different kinds of grains can be revealed from the scanning electron microscopy and energy-dispersive X-ray spectrometer results. High performance of microwave dielectric properties were obtained in the (Li_0.5Bi_0.5)(W_0.6Mo_0.4)O ₄ ceramic sintered at 620°C with a relative permittivity of 31.5, a Qf value of 8500 GHz (at 8.2 GHz), and a temperature coefficient value of +20 ppm/°C. Complex dielectric spectra of pure (Li_0.5Bi _0.5)WO₄ ceramic gained from the infrared spectra were extrapolated down to microwave range, and they were in good agreement with the measured values. The (Li_0.5Bi_0.5)(W_1-xMo _x)O₄ (0.0 ≤ x ≤ 1.0) ceramics might be promising for low temperature co-fired ceramic technology.