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.
- Garnet structure
- Microwave dielectric properties