NaCa4V5O17: A low-firing microwave dielectric ceramic with low permittivity and chemical compatibility with silver for LTCC applications

Phase formation, crystal structure and dielectric properties of NaCa4V5O12 ceramics fabricated via a solid state reaction route at relatively low temperatures (780-860 degrees C) were investigated. NaCa4V5O12 crystallizes in a triclinic structure. Dielectric properties were measured based on the Hakki-Coleman post resonator method at microwave frequency. Specially, a specimen sintered at 840 degrees C demonstrated balanced dielectric properties with a permittivity epsilon(r) = 9.72, a quality factor Q x f = 51,000 GHz, and a temperature coefficient of resonance frequency tau(f) = -84 ppm/degrees C. NaCa4V5O12 ceramics showed excellent chemical compatibility with Ag metal electrodes. Besides, the thermal stability of resonance frequency was effectively adjusted through formation of composite ceramics between NaCa4V5O12 and TiO2 and a near-zero tau(f) (similar to)1.3 ppm/degrees C accompanied with epsilon(r) = 14.9 and Q x f = 19,600 GHz was achieved when 50% mol TiO2 was added. All the merits render NaCa4V5O12 a potential candidate for multilayer electronic devices.