Structure and microwave dielectric properties of BaAl2-2x(CuSi)xSi2O8 ceramics

The sintering behavior, phase composition, microstructure and dielectric properties of BaAl2-2x(CuSi)(x)Si2O8 (x = 0, 0.01, 0.015, 0.02, 0.04, 0.06, 0.08) ceramics prepared via solid-state reaction route were investigated. Deviation between theoretical and experimental permittivity of BaAl2Si2O8 ceramics was discussed, and the theoretical and experimental temperature coefficient of resonant frequency (tau(f)) was also compared. The results showed that substituting (Cu0.5Si0.5)(3+) for Al3+ in matrix of hexacelsian could lower the sintering temperature from 1400 to 1200 degrees C and greatly promote the transformation of hexacelsian-to-celsian. And the single celsian phase was obtained for the compositions with x >= 0.02. The bulk densities, microstructure and dielectric properties of BaAl2-2x(CuSi)(x)Si2O8 ceramics were improved by doping a small quantity of (Cu0.5Si0.5)(3+) ions in the BaAl2Si2O8. The BaAl1.96(CuSi)(0.02)Si2O8 ceramics sintered at 1300 degrees C obtained good microwave dielectric properties: epsilon(r) = 6.7, Q x f = 31,276 GHz, tau(f) = - 17.17 x 10(-6) degrees C-1.