Effect of BaO on thermo-physical properties of lithium zinc silicate glass-ceramics

Lithium zinc silicate (LZS) glasses containing Li2O-ZnO-SiO2-Na2O-B2O3-BaO-P2O5 with different BaO/(BaO+ZnO) ratios were prepared by conventional melt and quench technique and subsequently converted into glass-ceramics. The effect of BaO/(BaO+ZnO) ratio on various thermo-physical properties was investigated by changing the ratio from 0 to 0.226. The crystalline phases were characterized by X-ray diffraction technique on the composite glass-ceramics, including Li3Zn0.5SiO4, Li2OZnSiO4 and cristobalite phase. The thermal expansion coefficient (TEC) in the temperature range 70-400 degrees C increased from 107 x 10(-7) to 141 x10(-7)/ degrees C. The increase in expansion coefficient was associated with the formation of different phases which in turn influenced the rigidity/bonding in the glass-ceramics. The microstructure was analyzed by scanning electron microscopy (SEM), and the grain size became bigger after the addition of BaO.