Phase formation, microstructure and microwave dielectric properties of Y2O3 and TiO2 doped BMW, i.e., Ba2(Mg1-2xY2xW1-x Tix)O6, ceramics were investigated. Up to the composition of x = 0.5, the BMW ceramics having an ordered cubic structure were only observed and no secondary phase such as BaWO4 was detected. As the value of x increased, the lattice parameter increased linearly, implying that a substitutional solid solution occurred. A dense microstructure was observed. The grain shapes was certainly a polyhedron, indicating that the solid phase sintering occurred. As the x value increased, the dielectric constant (εr) exhibited a tendency to increase slightly. The quality factor (Q × f0) sintered at 1700 oC increased up to x = 0.02 and then saturated. All of the compositions sintered at 1700 oC exhibited negative values of the temperature coefficient of resonant frequency (τf). The absolute value of τf decreased as the x value increased. Dielectric constant (εr), quality factor (Q × f0) and temperature coefficient of resonant frequency (τf) of the composition of x = 0.05, i.e., Ba2(Mg0.40Y0.10W0.45Ti0.10)O3, sintered at 1700 oC, were 19.6, 162,794 GHz, and -11.5 ppm/oC, respectively.

Keywords: Ba2(MgW)O6, Ordered perovskite, Polyhedron, Solid phase sintering, Microwave dielectrics