A model was proposed to calculate several thermodynamic parameters for the initial-stage sintering of an alumina powder obtained after calcinations at 900 degrees C for 2 h of a precursor. The precursor was synthesized by an alumina sulphate-excess urea reaction in boiling aqueous solution. The cylindrical compacts of the powder with a diameter of 14 mm were prepared under 32 MPa by uniaxial pressing using oleic acid (12% by mass) as binder. The compacts were fired at various temperatures between 900 and 1400 degrees C for 2 h. The diameter (D) of the compacts before and after firing was measured by a micrometer. The D Value after firing was taken as a sintering equilibrium parameter. An arbitrary sintering equilibrium constant (K,) was calculated for each firing temperature by assuming K-a = (D-i -D)/(D-D-f), where D-i is the largest value before sintering and D-f is the smallest value after firing at 1400 degrees C. Also, an arbitrary change in Gibbs energy (Delta G(a)degrees) was calculated for each temperature using the K-a value. The graphs of In K-a vs. 1/T and Delta G(a)degrees vs. T were plotted, and the real change in enthalpy (Delta H degrees) and the real change in entropy (AS') were calculated from the slopes of the obtained straight lines, respectively. Inversely, real Delta G degrees and K values were calculated using the real Delta H degrees and Delta S degrees values in the Delta G degrees = -RT In K = Delta H degrees-T Delta S degrees relation. The best fitting Delta H degrees and Delta S degrees values satisfying this relation were found to be 157,301 J mol(-1) and 107.6 J K-1 mol(- 1), respectively. (c) 2008 Elsevier B.V. All rights reserved.