STUDIES ON THE THERMAL-CHANGE AND INTERMEDIATE INVOLVED IN THE SYNTHESIS OF GAMMA-MO2N

The thermal change in the synthesis of gamma-Mo2N by temperature-progr ammed reaction of MoO3 with ammonia has been studied by differential t hermal analysis (DTA) technique, IR, BET and XRD measurements. The DTA results show that both exothermic and endothermic peaks appear in the process, With the increase of temperature-elevation rate, the areas o f the exothermic peaks increase, and the areas of the endothermic peak s decrease, XRD and IR results show that the exothermic peaks are attr ibuted to the reduction of MoO3 to MoO2, and the endothermic peaks can be assigned to the nitridation of MoO2 to gamma-Mo2N. The nitriding p roduct is gamma-Mo2N at the lower rates of increasing temperature (les s than or equal to 3 K/min), whereas the products are gamma-Mo2N and M oO2 at the higher heating rates (greater than or equal to 5 K/min). An d the higher the rate, the more MoO2 was formed in the final product. It is suggested that NH3 first interacts with MoO3 and reduces the MoO 3 into MoO2, and then the MoO2 is nitrided into gamma-Mo2N.