Preparation and characterization of MgO-Al2O3-SiO2 glass-ceramics with different MgO/Al2O3 ratio and La2O3 addition
Lingli Zhan, Han Jia, Chao Jiang, Tiesong Lin, Hong Li, Mitang Wang, Dehua Xiong
Abstract
MgO-Al 2 O 3 -SiO 2 (MAS) glass-ceramics were prepared by traditional melting and sintering method, and the effects of MgO/Al 2 O 3 ratios and La 2 O 3 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/Al 2 O 3 ratio from 0.69 to 0.47 can increase the characteristic temperatures of transition temperature ( T g ) and crystallization peak temperature ( T p ) in MAS parent glass. The reduction of MgO/Al 2 O 3 ratio could promotes the precipitation of α-cordierite phase (Mg 2 Al 4 Si 5 O 18 ), and the grain size of α-cordierite phase were increased from 200 to 500 nm. When the MgO/Al 2 O 3 ratio was 0.63, the MA-2 sample has the highest flexural strength of 127.46 MPa. Furthermore, we also investigated the influence of La 2 O 3 addition on the structure and properties of MAS glass-ceramics by employed MA-2 sample as a reference. The results show both the T g (742–748 °C) and T p (936–943 °C) of parent glass exhibit a slightly increasing with the La 2 O 3 content was increased from 0.0 to 2.0 wt%. The La 2 O 3 addition show a negligible influence on the crystal phase and morphology of MAS glass-ceramics. With increasing of the La 2 O 3 content, the MAS glass-ceramics samples have a larger density (2.58–2.76 g/cm 3 ) and a better chemical stability, and the CTE (6.12–8.17 × 10 −6 /°C), ε r (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.