The sintering and microwave dielectric characteristics of MgO-CaO-Al2O3-SiO2 glass-fluxed Ba(Mg1/3Ta2/3)O3 ceramics

Samples of 6 wt.% MgO-CaO-Al2O3-SiO2 (MCAS) glass-fluxed Ba(Mg1/3Ta2/3)O-3 ceramics are investigated, and its sintering and microwave dielectric properties are measured. The densification of the MCAS-fluxed Ba(Mg1/3Ta2/3)O-3 ceramics can be performed well at 1350 degreesC. Although the 1350 degreesC-sintered Ba(Mg1/3Ta2/3)O-3 ceramics own 96.3% theoretical density, the satellite phases of Ba5Ta4O15, Ba4Ta2O9, Ba7Ta6O22 and Mg4Ta2O9 are difficult to eliminate completely. As the sintering temperatures increase from 1250 to 1450 degreesC, the microwave dielectric properties of MCAS-fluxed Ba(Mg1/3Ta2/3)O-3 ceramics change as follows: The epsilon(r) values first decrease, saturate at 1350 degreesC-sintered ceramics and then slightly increase. The Q x f values first increase, saturate at 1350 degreesC-sintered ceramics and then slightly decrease. The tau(f) values linearly shift from 95.3 to - 39.9 ppm/degreesC. (C) 2002 Published by Elsevier Science B.V.