The nucleation and crystallization of MgO-B2O3-SiO2 glass

The nucleation and crystallization of MgO-B2O3-SiO2 (MBS) glass were studied by means of a non-isothermal, thermal analysis technique, X-ray diffraction and scanning electron microscopy. The temperature range of the nucleation and the temperature of the maximum nucleation rate for MBS glass were determined from the dependences of the inverse temperature at the DSC peak (1/7(p)) and the maximum intensity of the exothermic DSC crystallization peak ((delta T)(p)) on the nucleation temperature (T-n). For MBS glass the nucleation occurred at 600-750 degrees C, with the maximum nucleation rate at 700 degrees C, whereas the nucleation and crystal growth processes overlapped at 700 degrees C<T <= 750 degrees C. The analyses of the non-isothermal data for the bulk MBS glass using the most common models (Ozawa, Kissinger, modified Kissinger, Ozawa Chen, etc.) revealed that the crystallization of Mg2B2O5 was three-dimensional bulk with a diffusion-controlled crystal growth rate, that n=m=1.5 and that the activation energy for the crystallization was 410-440 kJ/mol. (C) 2011 Elsevier Ltd. All rights reserved.