NEUTRON-DIFFRACTION STUDY OF GAMMA-FE AT HIGH-PRESSURE

Face-centered-cubic iron (gamma-Fe) coherently precipitated in a singl e crystal of Cu has been studied by neutron diffraction at high pressu res up to 0.9 GPa and in the temperature range from about 5 to 110 K. It undergoes antiferromagnetic ordering at 67 +/- 2 K at ambient press ure. The ordering temperature T(N) monotonically decreases with increa sing pressure following a relation T(N)(K) = 67 - 12.8p - 11.1p2 -6.17 p3, where p is in units of GPa. The change of T(N) in gamma-Fe is disc ussed in terms of the volume change caused by pressurization or by all oying.