High pressure behavior of ZrW2O8: Gruneisen parameter and thermal properties

High pressure Raman spectroscopic studies are carried out on negative therm al expansion material ZrW2O8. The system exhibits amorphization at 2.2 +/- 0.3 GPa via an intermediate orthorhombic phase. In the cubic phase most mod es below 50 meV are found to have negative Gruneisen parameter. Using the r eported phonon density of states thermal properties are calculated and comp ared with the reported results. In contrast to the earlier belief, the pres ent results show that modes of energies much higher than 10 meV also contri bute substantially to the negative thermal expansion.