We demonstrate that the mean-square atomic vibrations or Debye-Waller tempe
rature factors of cubic (bce and fcc) and hcp-metals can be related to aggr
egate shear moduli at different pressures and temperatures. We show that hi
gh-quality powder X-ray diffraction data, collected in diamond anvil cells,
provide sufficient information for Rietveld refinement and determination o
f temperature factors. For the first time, we have determined the shear mod
ulus at pressures over 90 GPa and temperatures over 1000 K, using a new met
hod based on a combination of thermal equation of state and measured mean-s
quare atomic vibrations of Low-pressure cubic alpha-Fe and high-pressure ep
silon-Fe phases. (C) 2000 Elsevier Science S.A. All rights reserved.