A Ca₅Ni₄(VO₄)₆ low loss microwave dielectric ceramic with A site deficient garnet structure was prepared via the conventional solid state reaction method. Ca₅Ni₄(VO₄)₆ sintered at 980°C for 4h to a relative density of 96.2% exhibits favorable microwave dielectric properties such as a permittivity of 10.9, a Q×f value of 96,500GHz, and a τ _f value of -63.6ppm/°C. Its large negative τ _f could be compensated by forming a solid solution with LiCa₂Mg₂V₃O₁₂, that led to improved properties with a near-zero τ _f =-3.7ppm/°C, ε _r =10.2, Q×f=59,300GHz for 0.8Ca₅Ni₄(VO₄)₆-0.2LiCa₂Mg₂V₃O₁₂ after sintering at 955°C for 4h. Further on, 0.8Ca₅Ni₄(VO₄)₆-0.2LiCa₂Mg₂V₃O₁₂ proved to be chemically compatible with Ag electrodes, so it might be a possible candidate for LTCC applications.

A Li₄WO₅ ceramic with rock salt structure was prepared by the solid-state reaction method and its microwave dielectric properties was demonstrated for the first time. It could be well densified at relatively low sintering temperature (~890°C). XRD and DTA analysis revealed a phase transformation from cubic to orthorhombic occured at 700°C. Excellent microwave dielectric properties with a near-zero temperature coefficient of resonant frequency ~-2.6ppm/°C, a relative permittivity ~8.6 and a quality factor ~23,100GHz (at 11.0GHz) was obtained. Li₄WO₅ was found to be chemically compatible with silver powders when sintered at 890°C. All the results indicate that the Li₄WO₅ ceramic is a promising candidate as a base material in low temperature cofired ceramic technology.