Low-temperature sintering and microwave dielectric property of Ba6-3xSm8+2xTi18O54 solid solution

Ba6-3xSM(8+2x)(1-y)Ti18O54-delta{delta=3y(x+4)} ceramics were developed in this study to lower the sintering temperature as well as to maintain the excellent microwave dielectric properties of tungsten-bronze-type like Ba6-3xSM8+2xTi18O54 solid solutions. Ba6-3xSm(8+2x)(1-y)Ti18O54-delta ceramics were prepared by a slight change in the mixing composition from the solid solutions area to Ba2Ti9O20 direction on the BaO-SM2O3-TiO2 ternary phase diagram. Effects of compositional parameters x and y on the density of the sintered body and the microwave dielectric properties were investigated. Ba4Sm9.15Ti18O53.72 (x = 2/3, y = 0.02) ceramics sintered at 1350degreesC demonstrated the excellent properties including a high relative permittivity (epsilon(r) = 81), high quality factor (Q . f = 10000 GHz) and low temperature factor of resonant frequency (tau(f) = -13 ppm/degreesC). These properties are almost equivalent to those obtained in Ba4Sm9.33Ti18O54 (x = 2/3) solid solutions which need higher fabricating temperatures than 1460degreesC. It was also shown that a ball-milling technique strongly affected the density of sintered body and the resulting relative permittivity.