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Anharmonicity and the equation of state for gold

Journal Article · · J. Appl. Phys.; (United States)
DOI:https://doi.org/10.1063/1.342969· OSTI ID:6566627

The temperature dependence of the thermodynamic and the elastic properties of elemental gold are found from published data. It is shown that measurements for (partialK/sub T//partialP)/sub T/ near 5.5 are more thermodynamically consistent than are higher values of this parameter which have been reported earlier. Using 5.5 for (partialK/sub T//partialP)/sub T/, we find that (partialK/sub T//partialT)/sub V/ is not zero but -11.5 x 10/sup -3/ GPa K/sup -1/ for high temperatures (T>theta/sub D/, where theta/sub D/ is the Debye temperature). One consequence of this is that above theta/sub D/ the thermal pressure, P/sub TH/, along the room-pressure isobar can be expressed as P/sub TH/(T)-P/sub TH/(300) = (7.14 x 10/sup -3/ +(partialK /sub T//partialT)/sub v/ ln(V/sub a//V)) x (T-300) GPa for T at absolute temperature and V/sub a/ being the volume at ambient conditions. These results give thermal pressure values near those previously reported at small compressions, but give lower thermal pressures at large compressions. This study suggests that in order to ensure thermodynamic consistency, the value of d ln ..gamma../d ln V is near 2.5--3.0 which is higher than values of 1.0 and 1.7 reported previously (..gamma.. is the Grueneisen ratio). Calculations giving the compressional and shear wave velocities, v/sub p/ and v/sub s/, are also presented.

Research Organization:
Institute of Geophysics and Planetary Physics University of California, Los Angeles, California 90024
OSTI ID:
6566627
Journal Information:
J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 65:4; ISSN JAPIA
Country of Publication:
United States
Language:
English