Sintering behavior and microwave dielectric properties of B2O3-La2O3-MgO-TiO2 based glass-ceramic for LTCC applications

A new low temperature co-fired ceramic is fabricated from B2O3-La2O3-MgO-TiO2 (BLMT) glass with ZnO, ZrO2 and TiO2 ternary fillers, and the sintering behavior, crystalline phases, microstructures and microwave dielectric properties of the glass-ceramics is investigated. The results show that its sintering process starts at about 640 °C and ends up mostly at higher than 710 °C. During the process, BLMT glass crystallizes forming LaBO3 and the filler ZnO reacts with and gets into the residue glass phase, while TiO2 and ZrO2 are stable. With increasing sintering temperature, dielectric constant and temperature coefficient of resonant frequency of the glass-ceramic decrease, while the quality factor firstly increases and then decreases. Typically, the glass-ceramic sintered at 860 °C for 20 min reaches a maximum density of 4.25 g/cm3 and has an excellent microwave dielectric properties with the dielectric constant of 14.08, quality factor of 41,600 GHz (at 8 GHz), and temperature coefficient of resonant frequency of −2.78 ppm/°C.