EFFECT OF BAWO4 ON THE MICROWAVE DIELECTRIC-PROPERTIES OF BA(MG1/3TA2/3)O3 CERAMICS

Physical and microwave dielectric properties of complex perovskite Ba(Mg1/3Ta2/3)O2 ceramics have been investigated as a function of the amount of BaWO4 in the temperature range from 20-degrees to 80-degrees-C at 10.5 GHz. Up to 0.05 mol BaWO4 addition, the lattice constant ratio (c/a), ordering parameter, apparent density, and unloaded Q all increase, due to the increase in the substitution of Ta5+ ions of Ba(Mg1/3Ta2/3)03 by W6+ ions from the melted BaWO4 at above 1430-degrees-C. With further addition of BaWO4, the unloaded Q decreases, due to an increase of the BaWO4 phase. The temperature coefficient of resonant frequency (TCF) can be controlled by the volume mixture rule of Ba(Mg1/3Ta2/3)03 and BaWO4. When 0.09 mol BaWO4 is added, TCF becomes 0 ppm/-degrees-C.