Lattice dynamical calculation of isotropic negative thermal expansion in ZrW2O8 over 0-1050 K

We report detailed lattice dynamical calculations of the large isotropic ne gative thermal expansion (NTE) over 0-1050 K in ZrW2O8 in its cubic phase. The results bring out the unusually dominant quantitative contributions to NTE of the transverse acoustic, and librational and translational optic pho nons below 8 meV. The contributions of these phonons are reduced in the hig h pressure orthorhombic phase which therefore shows NTE only below 270 K. T he calculations show a fair agreement with the published thermal expansion data in both phases. [S0163-1829(99)14233-3].