Effects of chemical ordering and homogeneity on microwave dielectric properties of LaGaO3-SrTiO3 compounds

(1-x)LaGaO3-xSrTiO3 (x = 0-0.6) microwave dielectric ceramics were synthesized by using conventional solid-state reaction method and sintered at 1450 degrees C with different sintering conditions. The variations of micro-structure, relative density, and phase formation were observed by different composition and sintering conditions. The microwave properties, such as permittivity/dielectric constant (epsilon r), quality factor (Qf), and temperature coefficient of resonant frequency (TCF, tau f) at a high frequency were investigated in terms of lattice distortion, chemical ordering, and chemical homogeneity according to the composition and equilibrium sintering condi-tions. A maximum Qf-64,900 GHz was observed at x = 0, and the best tau f -0 ppm/degrees C was obtained at x = 0.4. Consequently, it was found that the permittivity is related mainly to the lattice distortion, whereas the quality factor is primarily affected by chemical ordering and chemical homogeneity of the microstructure-induced composition.