CdZnTe crystals were grown by the vertical Bridgman technique using boron oxide for preventing material decomposition. The experiments show that a boron oxide layer completely encapsulates the crystal during growth, so that the crystal grows without direct contact with the crucible. The origins of this effect are investigated. In this work it is shown that boron oxide and quartz create a mixing layer at high temperature. This layer explains the reason for the good wetting of the quartz crucible by boron oxide. (c) 2008 Elsevier B.V. All rights reserved.