A Novel Low‐Firing and Low Loss Microwave Dielectric Ceramic Li 2 Mg 2 W 2 O 9 with Corundum Structure

The crystal structure and microwave dielectric properties of a novel low‐firing compound Li 2 Mg 2 W 2 O 9 were investigated in this study. The phase purity and crystal structure were investigated using X‐ray diffraction analyses and Rietveld refinement. The best microwave dielectric properties of the ceramic with a low permittivity (ε r ) ~11.5, a quality factor ( Q × f) ~31 900 GHz (at 10.76 GHz) and a temperature coefficient of the resonant frequency (τ f ) ~ −66.0 ppm/°C were obtained at the optimum sintering temperature (920°C). CaTiO 3 was added into the Li 2 Mg 2 W 2 O 9 ceramic to obtain a near zero τ f , and 0.93Li 2 Mg 2 W 2 O 9 –0.07CaTiO 3 ceramic exhibited improved microwave dielectric properties with a near‐zero τ f ~ −1.3 ppm/°C, a ε r ~ 21.6, a high Q u × f value ~20 657 GHz. The low sintering temperature and favorable microwave dielectric properties make it a promising candidate for LTCC applications.