Negative-thermal-expansion ZrW2O8. Elasticity and pressure
Abstract
The elasticity of the negative thermal expansion (NTE) compound ZrW2O8 is rather strange: the solid softens as its volume decreases on warming. Does ZrW2O8 also soften when pressure alone is applied? Using pulse-echo ultrasound in a large-volume moissanite anvil cell, we find an unusual decrease in bulk modulus with pressure at 300K. Our results are inconsistent with conventional lattice dynamics, but a framework-solid-based non-linear model with many degrees of freedom predicts elastic softening as increases in either temperature or pressure reduce volume. The pressure-induced phase transition from α-ZrW2O8 (cubic) to γ-ZrW2O8 (orthorhombic) is found to take place at 0.5 GPa, result confirmed by Raman spectroscopy.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2007
- Bibcode:
- 2007APS..MARJ20010P