Crystallization, sinterability, and dielectric properties of MgO–Al2O3–SiO2 glass-ceramics doped with TiO2

The effects of TiO 2 on crystallization, microstructure, thermal, and dielectric properties of MgO–Al 2 O 3 –SiO 2 (MAS) glass-ceramics were investigated. The results showed that with the TiO 2 content increasing, the glass transition temperature ( T g ) increased gradually, while the onset of crystallization temperature ( T x ) and crystallization peak temperature ( T p ) increased firstly and then decreased. The main crystalline phase for all the samples was μ -cordierite. β-Quartz and α-cordierite precipitated as the minor crystalline phases with TiO 2 content ≥ 2 mol%. A small amount of TiO 2 could promote the sintering process and improve the dielectric properties of MAS glass-ceramics. However, an excess of TiO 2 addition could worsen the sintering and dielectric properties. The addition of TiO 2 was beneficial to decrease the coefficient of thermal expansion (CTE). The MAS glass-ceramics doped with 2 mol% TiO 2 heated at 925 °C showed excellent properties: high density (2.64 g/cm 3 ), low CTE value (3.34 × 10 –6 /°C), low dielectric constant (5.44), and dielectric loss (2.17 × 10 –3 ) at 1 MHz, which was a promising material for LTCC applications.