## 5aPA2. The determination of physical properties at high pressure using a high-temperature database from resonant ultrasound spectroscopy (RUS) measurements.

### Session: Friday Morning, May 17

### Time: 8:40

**Author: Orson L. Anderson**

**Author: Hyunchae Cynn**

**Author: Donald G. Isaak**

**Location: Inst. of Geophys. and Planet. Phys., UCLA, Los Angles, CA 90095-1567**

**Abstract:**

Using the RUS technique called rectangular parallelepiped resonance, a
large database on elastic constants and associated thermoelastic parameters
extending from 300 K up to as high as 1800 K (P=0) has been established at UCLA.
Temperature derivatives of the C[inf ij]'s have been determined with
considerable precision. It has been shown how the pressure derivatives of
elastic constants ((cursive beta)C[inf ij]/(cursive beta)P)[inf T] can be
approximated from ((cursive beta)C[inf ij]/(cursive beta)T)[inf P]. Agreement
with experiment is quite good in some cases. Extending this method to high
pressure (>3 GPa) requires evaluation of the volume dependence of the parameter,
((cursive beta)P/(cursive beta)T)[inf V]=(alpha)K[inf T], where (alpha) is
thermal expansivity and K[inf T] is the isothermal bulk modulus. Again, this is
done from temperature C[inf ij] data, but it requires one datum on pressure,
K[inf 0][sup ']=((cursive beta)K[inf T]/(cursive beta)P)[inf T] (P=0). From the
data, the temperature at which (alpha)K[inf T] becomes independent of volume was
predicted. The theory agrees well with experiment for all solids tested (NaCl,
MgO, Al[inf 2]O[inf 3], Mg[inf 2]SiO[inf 4], CaO).

from ASA 131st Meeting, Indianapolis, May 1996