Isothermal in situ observation of crystal growth in Li2B4O7 glass

We report in situ optical studies for the kinetics of crystal growth in Li2B4O7 glass. It has been found that the crystals grow up to the large size of 30-50 mum before they impinge on each other and linearly grow with time at various temperatures. We have also performed isothermal differential scanning calorimetry (DSC) measurements for the comparison of growth kinetics with in situ optical measurements. The Avrami exponent that is used to describe the crystallization kinetics has been determined to be 4 with DSC measurements, indicating that the crystallization mechanism is in the interface-controlled growth with a constant nucleation rate. This DSC investigation agrees well with the result of in situ optical observations. (C) 2002 Elsevier Science Ltd. All rights reserved.