X ray diffraction compression studies of hematite under hydrostatic, isothermal conditions

Compression data for α‐Fe2O3 were collected using two independent X ray diffraction techniques in which a sample was compressed under hydrostatic conditions. Samples of varying quality were used. In each case, a value of 1.99 ± 0.06 Mbar was calculated for K0, assuming a value of 4.0 for K0′. These data are in good agreement with the value obtained by Lieberman and Schreiber (1968) using ultrasonic methods. The bulk modulus was found to be lower, however, than an earlier, nonhydrostatic value of 2.28 Mbar reported by Bassett and Takahashi (1974). The sample of highest purity produced data which deviate from the other observed data in the region of 30 kbar. This discrepancy may be due to the Morin transition.