Mössbauer and magnetic study of the antiferro to ferrimagnetic phase transition in Fe9S10 and the magnetokinetics of the diffusion of iron atoms during the transition

Abstract

Mössbauer effect and xray studies of the phase transition in iron hexammine saltsThe anti ferromagnetic to ferrimagnetic phase transition referred to as the A transition in Fe9SlO has been explained by many workers on the basis of a structural change without any experimental evidence. Our Miissbauer and X-ray diffraction results support Lotgering's suggestion that the ferrimagnetism at about 493 K arises from the 4C superstructure. The antiferromagnetic to ferrimagnetic (A) phase transition is explained in terms of a vancancy rearrangement. Using absolute reaction rate theory and measurements of magnetization as a function of time at constant temperature around the transition, coefficients of diffusion for iron atoms along the C axis have been determined over the range 440 to 484 K and found to be 10-18 em' /sec.

Valleriite, a Natural Two-Dimensional Composite: X-ray Absorption, Photoelectron, and Mössbauer Spectroscopy, and Magnetic Characterization

“…The room-temperature spectra of both samples are dominated by a central signal, whose relative intensities (60–75%) correlate with the share of iron in valleriites derived from XAFS, XRD, and EDX. The spectrum of valleriite-1 is fitted with a major doublet d1 with the isomer shift (IS) of 0.38 mm/s and QS of 0.64 mm/s, which is attributed to paramagnetic Fe 3+ in tetrahedral coordination with S in the sulfide sheets of valleriite, in accordance with the previous studies, ,,,− and three six-line Zeeman components with the isomeric shift (IS) of 0.66 mm/s and hyperfine fields (H) of 223-201 (Table S3) attributable to high-spin Fe 2+ atoms in pyrrhotite Fe 1– x S. − …”