Sintering behavior and microwave dielectric properties of (1−x)Li2TiO3+xLiF ceramics prepared by enhanced sintering

Sintering behavior, structure and microwave dielectric properties of (1−x)Li2TiO3+xLiF (0≤x≤0.7) ceramics prepared by enhanced sintering were studied by thermal dilatometry, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM ), Raman spectra and microwave resonant measurement. It was found that the short range ordering and order–disorder phase transition temperature in this case increased compared with that observed for the specimen prepared from prealloyed powders because of the compositional inhomogeneity. The early stage sintering was enhanced by the chemical potential gradient originated from the compositional gradient between Li2TiO3 and LiF. However unequal diffusion rates between LiF and Li2TiO3 particles left behind large pores in the sintered bodies. Transient liquid phase sintering was confirmed in the x≥0.2 compositions. An optimized microwave dielectric properties with εr of ~22.4, Q×f of ~110,000 GHz and τf of ~3.2 ppm/°C could be obtained for the x=0.1 composition after sintering at 1100 °C/2 h.