Reconciliation of ab initio theory and experimental elastic properties of Al2O3

Abstract

Lattice dynamics and elasticity of silver thiogallate ( AgGaS 2 ) from ab initio calculations Ab initio calculations of the basic properties of solids have advanced significantly, and it is now possible to simply access a crystal structure database, and from the given constituent atoms and their positions, calculate reasonably accurate values for elastic constants and thermomechanical properties that may be derived from them. However, progress has been impeded by a unique discrepancy involving the sign of one of the elastic constants of an important material: Al 2 O 3 . In this letter, this longstanding discrepancy is resolved with experimental measurements.

The effect of anisotropy on the deformation and fracture of sapphire wafers subjected to thermal shocks

“…The values of C ij are quite consistent in the literature. For example, C 11 = 4.968 (10 12 dynes/cm 2 ), C 33 = 4.981, C 44 = 1.474, C 13 = 1.57, and C 14 = −0.22 in [4]; C 11 = 497.6 (GPa), C 12 = 162.6, C 13 = 117.2, C 14 = 22.9, C 33 = 501.8, and C 44 = 147.2 in [5]; C 11 = 497.5 (GPa), C 12 = 162.7, C 13 = 115.5, C 14 = 22.5, C 33 = 503.3, and C 44 = 147.4 in [6]. Even though the independent elastic constants are only six, they are located in the elastic matrix in such a way that the material is not orthotropic in the coordinate system x 1 x 2 x 3 , despite the three-fold symmetry of the crystal.…”

Ab initio molecular dynamics of Al irradiation-induced processes during Al2O3 growth

“…2 Generally, alumina is a stiff, refractory compound with commercial relevance. [3][4][5] ␣-Al 2 O 3 is nowadays widely used for instance in surface protection applications as well as microelectronics. 6,7 On the other hand, ␥-Al 2 O 3 is exceedingly valuable in catalysis.…”

A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

“…In fact, the sound resonant technique is a kind of nondestructive test method widely used [10][11][12][13][14][15][16][17][18]. The velocity and attenuation of fluid in a regular cavity or the elastic constants of solid bar sample can be measured accurately by using resonant ultrasound spectroscopy (RUS) with high precision [10][11][12][13][14].…”