Synthesis and energetics of yellow TaON

From the standard enthalpy of formation of tantalum oxynitride TaON, determined by oxidative drop solution calorimetry, it is possible to explain its particular synthesis conditions from Ta2O5 and NH3, i.e. the use of wet ammonia which prevents the formation of tantalum nitride Ta3N5. Thermogravimetric analyses were performed to study both the ammonolysis of Ta2O5 and the oxidation in air of Ta3N5 and TaON. TaON powder was prepared, which bright yellow color agrees well with its electronic structure. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.