Microwave dielectric properties of Li2W2O7 ceramics improved by Al2O3 addition

The effect of Al2O3 addition on the densification, sintered behavior, phase composition and microwave dielectric properties of Li2W2O7 ceramics prepared by conventional solid-state reaction method had been investigated. The structure, phase composition and surface morphology were studied by X-ray diffraction, EDX and scanning electron microscopy techniques, respectively. Only two phases Li2W2O7 and Al2O3 were observed in all specimens. The sintering time of Li2W2O7 ceramics with Al2O3 addition could be effectively reduced from 4 h to 2 h. The results showed that the doping of Al2O3 could promote the growth of uniform grain and improve effectively the quality factor and temperature coefficient of resonant frequency (tau(f)). The 3Li(2)W(2)O(7)-Al2O3 ceramics sintered 700 degrees C for 2 h exhibited epsilon(r) of 8.2, Q x f of 20,550 GHz, and tau(f) of -112 ppm/degrees C. The good microwave dielectric properties and relatively low sintering temperature would make 3Li(2)W(2)O(7)-Al2O3 ceramics promising candidate as LTCC dielectrics for LTCC applications. (C) 2018 Published by Elsevier B.V.