Influence of sintering temperature on microwave dielectric properties, structure and lattice modes of Ba(Zn < inf > 1/3 < /inf > Ta < inf > 2/3 < /inf > )O < inf > 3 < /inf > resonators

Abstract

The phase pure Ba(Zn1/3Ta2/3)O3 ceramic material was prepared using solid state reaction method. In order to achieve higher density ( > 97 %) and low dielectric loss at lower sintering temperature, the material was pre-ball milled, sieved and 1 wt% of PVA binder was added. The microwave dielectric properties, long range ordering of Zn/Ta sites were studied by varying the sintering temperature. The lattice distortion caused by slight diffusion of Ba2+ ions into Zn2+ sites is observed at higher sintering temperature due to ZnO loss. The stresses caused by lattice distortion associated with 1:1 and 1:2 ordering is discussed using Raman spectroscopy and correlated with dielectric loss tangent. The stabilized grain boundaries as well as 1:2 order structures are playing an important role in changes of dielectric loss tangent value. The best microwave dielectric properties of εr = 30 and Q × fo = 119 THz and near zero temperature coefficient of resonance frequency at 8.51 GHz were obtained for the samples sintered at 1550 °C for 4 h.