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

Abstract

The effects of TiO2 on crystallization, microstructure, thermal, and dielectric properties of MgO–Al2O3–SiO2 (MAS) glass-ceramics were investigated. The results showed that with the TiO2 content increasing, the glass transition temperature (Tg) increased gradually, while the onset of crystallization temperature (Tx) and crystallization peak temperature (Tp) 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 TiO2 content ≥ 2 mol%. A small amount of TiO2 could promote the sintering process and improve the dielectric properties of MAS glass-ceramics. However, an excess of TiO2 addition could worsen the sintering and dielectric properties. The addition of TiO2 was beneficial to decrease the coefficient of thermal expansion (CTE). The MAS glass-ceramics doped with 2 mol% TiO2 heated at 925 °C showed excellent properties: high density (2.64 g/cm3), 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.