Generalized Gruneisen parameters of elastic waves and the low-temperature thermal expansion of alumina from its third-order elastic-constant data

The generalized Gruneisen parameters (GP's) of elastic waves propagating in different directions in aluminum oxide are calculated from the measured second- and third-order elastic constants. These GP's in alumina are found to have small but positive values. The Brugger gammas are evaluated and the low-temperature limit of the Gruneisen gamma is calculated using the procedure of Ramji Rao and Srinivasan. {Mathematical expression}L has the value 1.37, indicating that the thermal expansion of alumina is positive down to 0 K. © 1976 Plenum Publishing Corporation.