In situ observation of β‐BaB2O4 microcrystal growth in glass matrix

The morphological evolution and growth mechanism of β-BaB2O4 microcrystal in Li2B4O7-BaB2O4 glass (Li2O-B2O3-BaO) matrix were investigated by optical in situ observation method. And the crystallization temperature Tc has been examined by differential thermal analysis (DTA). It demonstrates that homogeneous distribution of hexagonal shaped BBO microcrystals with size up to several tens of microns is typical when temperature is much higher than Tc, however, heterogeneous nucleation occurs when annealing temperature is close to Tc. For the latter case, crystal clusters that consist of several microcrystal grains are obvious. When the crystals in one specific cluster grows larger, crystal motion occurs in glass matrix while their orientation and symmetrical shape keep nearly no changes. Additionally, the BBO microcrystal has been determined to grow nearly in linear with time, which suggests a mechanism of interface-controlled growth. Furthermore, the activation energy of BBO crystal growth in glass matrix is calculated which is around 2.4 eV. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)