A lithium aluminium borate composite microwave dielectric ceramic with low permittivity, near-zero shrinkage, and low sintering temperature

摘要： A low temperature co-fired dielectric material with low shrinkage during the sintering process can enhance the circuit design of electronic devices. Lithium aluminium borate composite ceramic with a composition of Li2O:Al2O3:B2O3=1:1:2 (abbreviated: LAB) was prepared by a traditional solid-state reaction method. These ceramics have a low sintering temperature (675–750 °C), low permittivity, and near-zero shrinkage. When the sintering temperature was 725 °C, the LAB ceramics exhibited a small shrinkage of ~2.4% and the best microwave dielectric properties with εr = 3.9, Q × f = 35?500 GHz, and τ? = -64 ppm/°C. The LAB ceramics sintered at 700 °C have near-zero shrinkage of ~ 0.4% and good microwave dielectric properties. The ceramics transformed from (Li2B4O7 and Al2O3) to (Li2Al2B4O10 and Li4Al4B6O17) phases with increasing the sintering temperature, which may be the reason why they show marginal shrinkage. In addition, the ceramics could be co-fired with Ag, indicating that this material is a good candidate for low-temperature co-fired ceramic devices.