Abstract
A measurement of complex elastic constants is made on two single crystal MgO specimens using a resonance method. The results on the real part of the elastic constants are consistent with those reported by CHANG and BARSCH (1969) and SPETZLER (1970) except for a small difference in C12. The elastic constants at a theoretical density of 3.584g/cm3 are C11= 2.978±0.004, C12=0.970±0.005, C44=1.563±0.002, Cs=(C11-C12)/2= 1.004±0.001, and K=(C11+2·C12)/3=1.639±0.006 in Mbar at 293K. The small deviations of the elastic constants in different specimens from the above valucs are well related to the deviation of the actual density from the theoretical one. The internal frictions relating to respective elastic constants are Q-111=0.23±0.61, Q-112=-0.35±1.79, Q-144=1.87±0.16, and Q-1s=0.51±0.14 in units of 10-4 at room temperature and 1MHz. The dominant dis-sipation is not caused by the shear on a plane of easy glide {110}<110>, but the shear on {100}.
