Effect of MgO addition on crystallization and properties of Li2O–ZnO–SiO2 glass-ceramics seals for copper

Abstract The properties of Li 2 O–ZnO–SiO 2 (LZS) glass-ceramics with addition of 6 mol% MgO were investigated. With MgO addition, the glass transition temperature ( T g ) and the crystallization temperature ( T c 1 , T c 2 ) all decreased. There were more cristobalite and Li 3 Zn 0.5 SiO 4 phases in the MgO-doped samples, according to the XRD analysis. The results of crystallization kinetics showed LZS with MgO addition has lower activation energy ( E ) and higher crystallization index ( n ) and reaction rate constant ( k ), indicating MgO in LZS system can promote crystallization. The microstructures also showed the MgO-doped glasses had higher crystallinity and larger grain size. The sample hardness with MgO addition was higher. The average thermal expansion coefficient ( α ) of the MgO-doped glass-ceramics in the temperature range 20–400 °C was from 153.2 × 10 −7  K −1 to 179.0 × 10 −7  K −1 , and it was lower than that of MgO-free glasses. MgO in LZS could make it more suitable for sealing with copper ( α  = 177 × 10 −7  K −1 ).