Preparation and characterization of MgO-Al2O3-SiO2 glass-ceramics with different MgO/Al2O3 ratio and La2O3 addition

Abstract

MgO-Al2O3-SiO2 (MAS) glass-ceramics were prepared by traditional melting and sintering method, and the effects of MgO/Al2O3 ratios and La2O3 contents on the microstructure and physicochemical properties of MAS glass-ceramics were studied. Herein, differential scanning calorimetry (DSC), X-ray diffraction (XRD), fourier-transform infrared spectrophotometer (FTIR), Field-emission scanning electron microscopy (FESEM), density, corrosion resistance, dielectric properties and thermal expansion coefficient (CTE) were carried out to evaluate the properties of both parent glass and glass-ceramics samples. The results show that adjusting the MgO/Al2O3 ratio from 0.69 to 0.47 can increase the characteristic temperatures of transition temperature (Tg) and crystallization peak temperature (Tp) in MAS parent glass. The reduction of MgO/Al2O3 ratio could promotes the precipitation of α-cordierite phase (Mg2Al4Si5O18), and the grain size of α-cordierite phase were increased from 200 to 500 nm. When the MgO/Al2O3 ratio was 0.63, the MA-2 sample has the highest flexural strength of 127.46 MPa. Furthermore, we also investigated the influence of La2O3 addition on the structure and properties of MAS glass-ceramics by employed MA-2 sample as a reference. The results show both the Tg (742–748 °C) and Tp (936–943 °C) of parent glass exhibit a slightly increasing with the La2O3 content was increased from 0.0 to 2.0 wt%. The La2O3 addition show a negligible influence on the crystal phase and morphology of MAS glass-ceramics. With increasing of the La2O3 content, the MAS glass-ceramics samples have a larger density (2.58–2.76 g/cm3) and a better chemical stability, and the CTE (6.12–8.17 × 10−6/°C), εr (5.04–6.17), and the flexural strength (127.46–150.15 MPa) also show an increased change trends. The prepared MAS glass-ceramics can be packaged with high expansion coefficient chips (such as GaAs) and is expected to become a potential candidate of dielectric materials for electronic devices, especially for high frequency applications in integrated circuits.