Glass transition and crystallization of ZnO-B2O3-SiO2 glass doped with Y2O3

The effect of Y2O3 on the glass transition kinetics, crystallization kinetics, phase separation and crystallization behavior of 60ZnO-30B(2)O(3)-10SiO(2) glass has been investigated by non-isothermal differential thermal analysis, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The glass transition activation energies E-g calculated by using both Kissinger and Moynihan model decrease from 668 kJ/mol to 573 kJ/mol for Kissinger model, and 682 kJ/mol to 587 kJ/mol for Moynihan model with the increase of yttrium oxide doping content from 0 to 6 mol%. And the glass crystallization kinetics parameters, crystallization activation energy E-c and Avrami exponent n stands for crystal growth, are also obtained on the basis of several well developed equations. Increase of about 58 kJ/mol in Ec values obtained by different theoretical equations is caused by addition of 6 mol% yttrium oxide into 60ZnO-30B(2)O(3)-10SiO(2) glass, and the Avrami exponent (n close to 2) suggests that crystal growth in 60ZnO-30B(2)O(3)-10SiO(2) glass doped with or without yttrium is mainly one-dimensional growth of crystals. The results on the phase separation and crystallization behavior occurred at 893 K and 993 K respectively for base and doped glass, are well consistent with the glass transition and crystallization kinetics results. Hence, addition of yttrium oxide into 60ZnO-30B(2)O(3)-10SiO(2) glass decrease the glass transition activation energy while increase the crystallization activation energy of glass, thereby the stability of glass structure is improved. Phase separation phenomenon and crystallization behavior occurred at glass surface provide some useful information for preparing glass ceramics with micro- or nano-crystals in surface.