Enhancement in microwave dielectric properties of (zn < inf > 1-x < /inf > mn < inf > x < /inf > ) < inf > 2 < /inf > tio < inf > 4 < /inf > ceramics through post-sinter annealing

Abstract

Polycrystalline manganese substituted zinc orthotitanate (Zn1-xMnx)2TiO4,(x = 0-0.20) ceramics were prepared by a conventional ceramic manufacturing route followed by solid state sintering at 1180 oC for 6 h (in air). The sintered pellets were further subjected to post-sinter annealing at three different temperatures of 1050 °C, 1080 °C and 1120 °C for 24 h. The increase in annealing temperature caused a marginal increase in densities associated with improvement in the dielectric properties. At microwave frequencies (7-8 GHz), the room temperature dielectric constant values for all the un-Annealed samples which were varying in the range 16 to 18 for the x = 0-0.20 samples, got marginally improved to 17 to 19 respectively, after annealing. A major jump in the quality factor (Qu.f) values, which indicated a reduction in dielectric loss, was noted. The Quf values which were ranging between 1430 and 6380 GHz for the sintered x = 0-0.20 samples, improved to 5925 and 9100 GHz respectively after annealing at 1120 °C. The improvement in the dielectric properties was attributed to improvement in both the densities and compositional homogeneity achieved after annealing apart from other factors such as grain size and the contribution of substituted Mn2+ ions.