Effect of hydrostatic pressure on the elastic constants ofV2O3

Abstract

The elastic constants of pure single-crystal ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ at 296 K are determined up to 4 kbar from measurements of the travel times of 30-MHz ultrasonic waves. Linear pressure dependences are found for all modes. Four elastic constants ${C}_{11}$, ${C}_{12}$, ${C}_{13}$, and ${C}_{33}$ have large positive pressure dependences. Comparison with results for $\ensuremath{\alpha}$-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ indicate that these large dependences are due in part to the highly anisotropic contraction of ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ under pressure. The softening with pressure of the shear elastic stiffness ${C}_{\mathrm{ST}}$ suggests that a high-pressure transition occurs in ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ between 150 and 250 kbar. Using the values and pressure dependences of ${C}_{11}$, ${C}_{12}$, ${C}_{13}$, and ${C}_{33}$, we calculate the changes in lattice parameters with pressure up to 140 kbar. Our results are compared with x-ray data of others.