Phase analysis and improvement of quality factor of Li2ZnTi3O8 ceramics by annealing treatment

Abstract

The Li2ZnTi3O8 ceramics were prepared using conventional solid state method and then annealed at various temperatures, from 900°C to 1075°C for 4h. The special effects of annealing treatment on microwave dielectric properties, phase composition and microstructure of Li2ZnTi3O8 ceramics were investigated. A single phase of Li2ZnTi3O8 ceramic was proved by the XRD pattern at all temperatures. Further, TiO2 phase in the annealed specimens at 1050 and 1075°C were confirmed as a secondary phase in the main Li2ZnTi3O8 phase. The SEM micrograph displays that increasing annealing temperature enlarges the grain size and an abnormal grain growth was observed above 1025°C. While the annealing temperature increases to 1000°C, the quality factor reaches to maximum value, and further increase in the temperature decreases it that could be related to the reduction of densification and the development of more pores at high temperatures. As the annealing temperature increased to 1075°C, the dielectric constant achieves a minimum value and the temperature coefficient of resonant frequency shifts to near zero. The Li2ZnTi3O8 ceramics annealed at 1000°C exhibit excellent microwave dielectric properties of Q×f=90,000GHz, ɛr=25.6 and τf=−10.8ppm/°C.