Microwave sintering of Ca _0.6La _0.2667TiO ₃ microwave dielectric ceramics

Ca _0.6La _0.2667TiO ₃ ceramics were prepared by conventional and microwave sintering techniques and their sinterability, microstructure, and microwave dielectric properties were investigated in detail for comparison. Densified Ca _0.6La _0.2667TiO ₃ ceramics were obtained by microwave sintering at 1350°C for 30 min and by conventional sintering at 1450°C for 4 h. An unusual phenomenon was found that some larger grains (grain size range: 8-10 μm) inclined to assemble in one area but some smaller ones (grain size range: 2-4 μm) inclined to gather in another area in the microwave sintered ceramics. The microwave dielectric properties of Ca _0.6La _0.2667TiO ₃ ceramics prepared by microwave sintering at 1350°C were as follows: dielectric constant (ε _r) = 119.6, quality factor (Qf ) = 17858.5 GHz, and temperature coefficient of resonant frequency (τ _f) = 155.5 ppm/°C. In contrast, the microwave dielectric properties of the ceramics prepared by conventional sintering at 1450°C were ε _r = 117.4, Qf = 13375 GHz, and τ _f = 217.2 ppm/°C.