**4. Interfacial boundary layer and microconvection during oxide crystal growth**

In crystal growth, interfacial gradients in velocity, concentration or temperature are often summarily referred to as boundary layers. The concept of interfacial boundary layer concerning of crystal growth has been thoroughly expounded by Franz Rosenberger (F. Rosenberger, 1993). The domain of liquid can be subdivided into two regions. Inside the boundary layer, the gradient is high, while out side the boundary layer, the gradient is negligible.
