Force Field and Elastic Constant of Corundum

Basing on ascription of the infrared spectra of corundum at 637, 583, 571, 436, 400 and 387 cm-1 given by BARKER and of Raman spectra of ruby at 751, 642, 578, 450, 432, 417 and 375 cm-1 obtained by KRISHNAN and on the modified formula of UREY-BRADLEY force field, the values for the normal frequency of corundum have been estimated. The data for the elastic constant derived from those for the force constant have been in good harmony with those obtained megascopically from the practical observation, being connected more sensitively with the bending and repulsive forces than with the stretching force. This view has also been comfirmed by evaluating variation in the internal coordinate in relation to the elastic stress. The values for the constants related to the stretching force and elasticity in the cases of corundum, rutile and quartz have been compared with one another.