P-V-T equation of state for ε-iron up to 80 GPa and 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils

In order to determine the P-V-T equation of state of epsilon-iron, in situ X-ray observations were carried out at pressures up to 80 GPa and temperatures up to 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils which was interfaced with synchrotron radiation. The present results indicate the unit cell volume at ambient conditions V-0 = 22.15(5) angstrom(3), the isothermal bulk modulus K-T0 = 202(7) GPa and its pressure derivative K-T0' = 4.5(2), the Debye temperature theta(0) = 1173(62) K, Gruneisen parameter at ambient pressure gamma(0) = 3.2(2), and its logarithmic volume dependence q = 0.8(3). Furthermore, thermal expansion coefficient at ambient pressure was determined to be alpha(0)(K-1) = 3.7(2) x 10(-5) + 7.2(6) x 10(-8)(T-300) and Anderson-Gruneisen parameter delta(T) = 6.2(3). Using these parameters, we have estimated the density of epsilon-iron at the inner core conditions to be similar to 3% denser than the value inferred from seismological observation. This result indicates that certain amount of light elements should be contained in the inner core as well as in the outer core but in definitely smaller amount. Citation: Yamazaki, D., et al. (2012), P-V-T equation of state for epsilon-iron up to 80 GPa and 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils, Geophys. Res. Lett., 39, L20308, doi: 10.1029/2012GL053540.