Dielectric properties of Ba(Mg,Zn)(1/3)Nb2/3O3 and effect of B2O3 and LiF addition

The dielectric and microwave properties of (x)BaZn1/3Nb2/3O3-(1-x)BaMg1/3Nb2/3O3 (BMZN) mixture were investigated. The complex perovskite-type ceramics Ba(Zn1/3Nb2/3)O-3 (BZN) and Ba(Mg1/3Nb2/3)O-3 (BMN) have a high dielectric constant (epsilon(r) = 39 and 33, respectively), but while BZN has a relative low firing temperature (similar to 1350 degrees C), BMN has a too high sintering temperature (> 1500 degrees C) to make it attractive in some technological applications. Mixing these two dielectric ceramics in different proportions and adding some sintering agents (like glassy B2O3 and LiF) the sintering temperature can be decreased, and XRD patterns indicates the formation of a solid solution for all x values investigated. The dielectric properties are preserved or even improved for some specific combinations. For BMZN (x= 1/4), without any dopants, the Q(f) factor is 76.7 THz for f = 7.6 GHz and the temperature coefficient of the resonant frequency tau(f) is -4 ppm/degrees C, which is the best value for BMZN. These values make BMZN compounds suitable for microwave resonator applications. We highlight in this paper that BMZN materials can be successfully sintered at low temperature (i.e. 940 degrees C), opening opportunities to manufacture base metal electrodes multilayer ceramic capacitors (BME-MLCC). (c) 2005 Elsevier Ltd. All rights reserved.