Thermal expansion of iron-rich alloys and implications for the Earth's core.

ABSTRACT: Understanding the thermal-chemical state of the Earth's core requires knowledge of the thermal expansion of iron-rich alloys at megabar pressures and high temperatures. Our survey of literature revealed a significant lack of such data. We have determined the unit-cell parameters of the iron-sulfur compound Fe(3)S by using synchrotron x-ray diffraction techniques and externally heated diamond-anvil cells at pressures up to 42.5 GPa and temperatures up to 900 K. The zero-pressure thermal expansivity of Fe(3)S is determined in the form alpha = a(1) + a(2)T, where a(1) = 3.0 +/- 1.3 x 10(-5) K(-1) and a(2) = 2.8 +/- 1.5 x 10(-8) K(-2). The temperature dependence of isothermal bulk modulus ((partial differential)K(T,0)/(partial differential)T)(P) is estimated at -3.75 +/- 1.80 x 10(-2) GPa K(-1

SUBMITTER: Chen B 

PROVIDER: S-EPMC1890464 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature