A new glass-ceramic material with dielectric constant Ɛᵣ~10-11 and optimum quality factor Q x ƒ~22,900 GHz was fabricated from 1MgO-1.2Al2O3-2.8SO2-1.2TiO2-xLa2O3 system, and the effects of La2O3 on crystallisation, microstructure, and dielectric properties of the material were investigated. The results show that the main crystalline phases in the glass-ceramics are lanthana-based perrierite, rutile and cordierite. As the content of La2O3 increases, the formation of perrierite is promoted, while that for rutile and cordierite is suppressed. Meanwhile, a gradual homogenization in the microstructure has been observed. Specifically, the interconnected network, the formation of which is mainly due to the aggregation of perrierite, disintegrates with the increase of x from 0.1 to 0.3 and is hardly seen when x=0.4, finally resulting in a homogenous microstructure with an overall uniform distribution of the phases and crystalline size.
