HILDEBRAND EQUATION OF STATE FOR MINERALS RELEVANT TO GEOPHYSICS

The Hildebrand thermal equation of state (EOS) is revived and applied to minerals appropriate to the earth's interior. The chief virtue of this EOS is that it escapes the necessity of evaluating a Grüneisen parameter at high compression and high temperature. The classical Grüneisen parameter is replaced by the product of two experimentally measured parameters: α, the coefficient of thermal expansivity, and KT, the isothermal bulk modulus. In order for the Hildebrand EOS to be useful in geophysical conditions it is necessary to show that α KT is, to a large extent, independent of volume. This can be done directly by experiment, following Yagi, or indirectly using thermodynamic formulae where other measurements are used in place of α KT. Four such tests are proposed, two of them following tests proposed by Swenson. The result indicates that most, if not all, of the close-packed minerals relevant to geophysics follow the rule that the value of α KT is to a satisfactory extent independent of compression. © 1979 Springer-Verlag.