ON THE CHEMICAL-TRANSPORT OF MOLYBDENUM U SING SBBR3 - EXPERIMENTS AND THERMOCHEMICAL CALCULATIONS

Mo migrates in a temperature gradient from the region of higher temper ature to the lower temperature using SbBr3 as transport agent. For var ious mean transport temperatures (750 less than or equal to T less tha n or equal to 1000 degrees C; (T) over bar=0,5 (T-1 + T-1; T-2 - T-1 = 100 degrees C) we observed small transport rates (m less than or equa l to 0,6mg/h) which rise up to 16 mg/h for higher transport agent conc entrations. Small amounts of MoO2 and Sb were detected beside Mo in th e sink. The observed solid phases in the sink are in agreement with th ermodynamical calculations by CVTrans which also demonstrate that the formation of MoO2 and Sb as well as the transport effect of SbBr3 are caused by traces of H2O from the quartz glass wall. The sequence of de position of Mo, MoO2 and Sb in the examined temperature range can be c alculated (CVTrans) and measured with the transport balance.