Development of optical system for high temperature in situ observation of oxide crystal growth

et al. 2007

The generation of bubble-inclusions during BaB 2 O 4 (BBO) crystal growth from high temperature solution has been optically observed by an in situ observation technique. It was found that bubbles are formed from the peripheries of some hexagonal defects in the (0001) plane of the growing crystal, which may be caused by the evaporation of the air-opened interface at the high temperature. In addition, atomic force microscope (AFM) was used to investigate the distribution of bubbles. Results revealed that the bubble generation and distribution depend strongly on the microscopic structure of the interface: on a rough interface, bubbles are easily formed and grow rapidly; however, they are greatly suppressed by step trains on a vicinal interface. In the latter case, the height value of a bubble is close to that of the step, which is in the order of several tens of nanometers.

Section: Methodsmentioning

confidence: 99%

Experimental study of bubble generation during β‐BaB₂O₄ single crystal growth

et al. 2007

“…The growth and observation system was described in previous work [9]. A short description is given below.…”

Section: Methodsmentioning

confidence: 99%

Effect of surface tension‐driven flow on BaB₂O₄ crystal growth from high temperature melt‐solution

Liu

et al. 2008

Self Cite

The surface tension driven-flow in BaB 2 O 4 (BBO) melt-solution is visualized by differential interference microscope coupled with Schlieren technique, and the streamline of the steady thermocapillary convection is found to be in form of an axially symmetric pattern. Based on the observation of BBO crystal rotation caused by the convective vortex, the widths of interfacial concentration, heat and momentum boundary layer are calculated. The effect of thermocapillary convection on boundary layer thickness is also investigated. Results show that the width of boundary layer decreases linearly with the increasing of dimensionless Marangoni number.

“…The observation experiments were performed in a high-temperature in situ observation system [8]. Firstly, a small piece of sample block was placed on a horizontal loop-shaped Pt wire heater and heated up to 1373 K for remelting.…”

Section: Methodsmentioning

confidence: 99%

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

Liu

et al. 2009

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.