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

Abstract

The morphological evolution and growth mechanism of β-BaB 2 O 4 microcrystal in Li 2 B 4 O 7 -BaB 2 O 4 glass (Li 2 O-B 2 O 3 -BaO) matrix were investigated by optical in situ observation method. And the crystallization temperature T c 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 T c , however, heterogeneous nucleation occurs when annealing temperature is close to T c . 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.