Sintering behavior, microstructure and dielectric performance of Al2O3 ceramic with addition of new Bi2O3-B2O3-SiO2-ZnO glass

Bi2O3-B2O3-SiO2-ZnO glass is an efficient sintering aid for ceramics, but there exist uncertainties about its origin and sintering mechanism. In this paper, the 20BBSZ glass containing 20 mol% Bi2O3 was designed to improve the sintering and dielectric properties of Al2O3 ceramics by adjusting B2O3/SiO2 ratio (r). The crystallization and sintering behavior of 20BBSZ glass and its glass network structure were studied by combining with thermal analysis and infrared spectroscopy. The effect of B2O3/SiO2 ratio on the microstructure, sintering behavior and dielectric properties of the 20BBSZ/Al2O3 composites were investigated. The factors affecting the dielectric properties are discussed. The following conclusions are obtained: (1) Sintering density affects dielectric properties obviously; (2) Formation of ZnAl2O4 and Al5BO9 hindered the densification of ceramics; (3) The 20BBSZ/Al2O3 composite sintered at 1000 (?)degrees C for 2 h has the excellent dielectric properties at r = 1/3 due to high density, epsilon(r) = 5.64, tan delta = 1 x 10(-3) at 500 MHz, and CET = 7.02 ppm(?)degrees C-1.