Oxidation of Thorium Nitrides

Abstract

An experimental study has been made on the oxidation of two thorium nitrides ThN and Th₃N₄, in oxygen under a pressure of 1/5 atm. The Th₃N₄ was prepared by reacting thorium hydride with N₂ gas, and the ThN by decomposing Th₃N₄ in vacuo. The thorium nitrides were idenfied by X-ray powder diffractometry. The values of N/Th ratio were determined by chemical analysis to be 0.90∼0.92 for ThN and 1.22 for Th₃N₄. Powder specimens of both thorium nitrides were isothermally oxidized in the temperature range of 340°∼480°C. The oxidation behavior of ThN powder was found to be independent of oxygen pressure (1/5∼1atm). The reaction kinetics of both thorium nitrides were found amenable to representation by linear plots for the most part of the reaction. The apparent activation energies were 18±3kcal/mole for ThN and 15±2kcal/mole for Th₃N₄. X-ray examination revealed the oxidation product of both nitrides to be solely ThO₂, and no other product was detected.