Anharmonicity of gold under high-pressure and high-temperature

In order to examine the pressure effect on the anharmonicity of Au, EXAFS spectra near Au L-3-edge were measured at the temperature range from 300 to 1000 K under pressures up to 14 GPa using large volume high-pressure devices and synchrotron radiation. The values of EXAFS Debye-Waller factors, sigma2 and sigma3 become smaller with the increase of pressure, which indicates that the potential width become narrower with pressure. The anharmonic effective pair potentials of Au, V(u) = au(2)/2! + bu(3)/3!, at 0.1 MPa. 6 and 14 GPa have been calculated. The pressure dependence of the coefficient of thermal expansion has also been evaluated. (C) 2002 Elsevier Science Ltd. All rights reserved.