Formation of MgO powders by using a combustion method and the thermodynamics of gas adsorption

Abstract

MgO and ZnO powders having highly uniform (100) surface exposure were synthesized by using a combustion method at an rf power. Mg or Zn pieces of a few millimeter size were mixed with carbon in a volume ratio of 2:1 and were placed in a carbon crucible. The quality of the powders was characterized by using X-ray and TEM investigations, which confirmed that the powders were a single phase with sizes smaller than a few hundred nanometers. The adsorption isotherms of Ar measured below the triple point (83.78 K) showed that 1) the amount of gas adsorbed on the MgO surface was approximately two times greater than that of the ZnO powder and that 2) the curvature of the isotherm step depended on the condition of the powder. These results demonstrate that the adsorption isotherm is strongly affected by the condition of the powder surface.