Relationship between dielectric properties and microstructure of nearly zero temperature coefficient of resonant frequency of forsterite ceramics

Abstract

High purity forsterite (Mg₂SiO₄) ceramics is one of the millimeter-wave dielectric having high quality factor Qf and low dielectric constant t_f. However, it has a negative temperature coefficient of resonant frequency t_f between -60 to -70 ppm/C. Rutile (TiO₂) that owing high t_f value (+450 ppm/C) was added to the ceramics in order to adjust the tf to zero. Two kinds of powders were prepared: one with 25 wt% TiO₂ added, and another with 30 wt% TiO₂. We found that the nearly zero t_f can be achieved by controlling the sintering duration at 1200C. The relationship between microstructure and dielectric properties was investigated.