Influence of W substitution on crystal structure, phase evolution and microwave dielectric properties of (Na0.5Bi0.5)MoO4 ceramics with low sintering temperature

In this work, the (Na0.5Bi0.5)(Mo1-xWx)O-4 (x = 0.0, 0.5 and 1.0) ceramics were prepared via solid state reaction method. All the samples can be well densified at sintering temperature about similar to 720 degrees C. Dense and homogeneous microstructure with grain size lying between 2 similar to 8 mu m can be observed from scanning electron microscopy (SEM). Microwave dielectric permittivity of the (Na0.5Bi0.5)(Mo0.5W0.5)O-4 ceramic was found to be temperature-independent in a wide range between 25 similar to 120 degrees C with a temperature coefficient of frequency (TCF) similar to-6 ppm/degrees C, a permittivity similar to 28.9, and Qf values 12,000 similar to 14,000 GHz. Crystal structure was refined using Rietveld method and lattice parameters are a = b = 5.281 (5) angstrom and c = 11.550 (6) angstrom with a space group I 4(1)/a (88). The (Na0.5Bi0.5)(Mo1-xWx)O-4 ceramics might be good candidate for low temperature co-fired ceramics (LTCC) technology.