Aggregate shear moduli of iron up to 90 GPa and 1100 K

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.