Relation between Valence Force Constants and Elastic Constants in α-Alumina: Evolution at High Temperatures

A general valence force field is determined from the experimental vibrational frequencies and elastic constants of α-Al2O3 in order to relate the macroscopic elasticity of this material to its microscopic elasticity characterized by the bond-stretching and angle-beading force constants. The evolution of the frequencies, elastic constants, and force field as a function of temperature is discussed.