Ultra-low Sintering Temperature Microwave Dielectric Ceramics Based on Na^sub 2^O-MoO^sub 3^ Binary System

The compounds in Na...O-MoO... system were prepared by the solid-state reaction route. The phase composition, crystal structures, microstructures, and microwave dielectric properties of the compounds have been investigated. This series of compounds can be sintered well at ultra-low temperatures of 505°C-660°C. The sintered samples exhibit good microwave dielectric properties, with the relative permittivities (...) of 4.1-12.9, the Q x f values of 19900-62400 GHz, and the ... values of -115 ppm/°C to -57 ppm/°C. Among the eight compounds in this binary system, three kinds of single-phase ceramics, namely Na...MoO..., Na...Mo...O... and Na...Mo...O... were formed. Furthermore, the relationship between the structure and the microwave dielectric properties in this system has been discussed. The average Na...-O and Mo...-O bond valences have an influence on the sintering temperatures in Na...O-MoO... system. The large valence deviations of Na and Mo lead to a large temperature coefficient of resonant frequency. The X-ray diffraction and backscattered electron image results show that Na...MoO... doesn't react with Ag and Al at 660°C. Also, Na...Mo...O... has a chemical compatibility with Al at 575°C. (ProQuest: ... denotes formulae/symbols omitted.)