Gibbs Energy Change of Carbothermal Nitridation Reaction of Al 2 O 3 to Form AlN and Reassessment of Thermochemical Properties of AlN

The experimental method for the high‐temperature reaction equilibria in the AlN‐Al 2 O 3 system has been established. The equilibrium N 2 ‐CO gas compositions coexisting with AlN‐ Al 2 O 3 ‐graphite have been successfully measured by quadrupole mass spectrometry and gas chromatography. From the obtained results, the standard Gibbs energy change of the forming reaction of AlN by carbothermal nitridation is determined at temperatures ranging from 1723 to 1899 K: image From the obtained result, the standard Gibbs energy of formation of AlN and the third‐law enthalpy of formation of AlN at 298.15 K are derived as image The disagreement between the present results and values in the NIST–JANAF thermodynamic table is discussed.