ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Naturally occurring samples of iwakiite, Mn1.1Fe1.9O4, have been annealed for 17 and 77 h at 1000 K in an investigation of order–disorder phenomena in Mn–Fe oxide spinels. Two distinct magnetic hyperfine patterns, which correspond to Fe- and Mn-rich phases, were observed in the 57Fe Mössbauer spectra for the two annealed samples. While the spectrum of the Fe-rich phase corresponds to a magnetically and crystallographically highly ordered α-Fe2O3-like phase, the Mn-rich phase exhibits considerable disorder, as indicated by very broad linewidths and a low value for Heff. Annealing for longer periods of times leads to a considerable increase in the ordering of the Mn-rich spinel phase, as evidenced by the considerable narrowing of the lines, from Γ=2.40 mm s−1 to Γ=1.17 mm s−1, and an increase in Heff from 318 to 417 kOe at 298 K. The Fe-rich, α-Fe2O3-like phase is not affected by further annealing, as expected. At 85 K, the 57Fe Mössbauer spectrum of the Mn-rich, spinel phase continues to exhibit rather broad lines, indicating the presence of significant cation disorder.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.355681
