High-performance (1-x)(0.2B2O3-0.8SiO2)-xTiO2 (x=0.025-0.1) glass matrix composites for microwave substrate applications

The (1-x)(0.2B(2)O(3)-0.8SiO(2))-xTiO(2) (x = 0.025-0.1) glass matrix composites were prepared by a solid state sintering method, and high relative density >97% was obtained when the sintering temperature was 975-1000 degrees C. The rutile and amorphous phases were indicated by XRD, and no crystallization of amorphous SiO2 or chemical reaction was observed. With increasing x from 0 to 0.1, the dielectric constant (epsilon(r)) increased slightly while the Qf value decreased, and the temperature coefficient of resonant frequency (tau(f)) increased from a negative to a positive value. The optimized microwave dielectric properties were obtained as following: epsilon(r) = 4.01, Qf= 66,800 GHz, tau(f) = -2.2 ppm/degrees C for x = 0.025 sintered at 1000 degrees C, and epsilon(r) = 4.22, Qf = 55,300 GHz, tau(f) = 3.1 ppm/degrees C for x = 0.05 sintered at 975 degrees C. The ultra-low epsilon(r), high Qf value and near-zero tau(f) indicate that the present glass matrix composites are excellent candidates as the microwave substrate materials. (C) 2018 Elsevier B.V. All rights reserved.