Mössbauer effect studies of ferrous oxides Fe1−xO

Abstract

Mössbauer measurements were performed at room temperature for a group of nonstoichiometric iron oxides of the Fe1‐xO type with 0.002≦x≦0.250. The measured spectra for the samples with x ranging from 0.002 to 0.083 represent quadrupole split Fe2+ doublets and an unseparated Fe3+ singlet. For the samples with x≧0.084 apart from asymmetric quadrupole splitting, a double Zeeman splitting appears, due to the formation ofmagnetite‐like clusters. The intensity ratio of the quadrupole pattern of the wüstite phase to the Zeeman pattern of the magnetite phase decreases with increasing x to zero for x = 0.250 (pure synthetized magnetite), which is in agreement with X‐ray diffraction analyses.

Size-dependent redox behavior of iron observed by in-situ single nanoparticle spectro-microscopy on well-defined model systems

“…The type of oxide formed is an important issue to be pursued since each oxide has distinct properties, affecting application in magnetism, optics, catalysis, wastewater treatment, and electronics. Fe 3 O 4 and Fe 2 O 3 are the most stable and common phases existing in nature and FeO is thermodynamically unstable 51 52 . The tendency of inter-conversion of oxides and non-stoichiometry arises due to different dispositions of ferrous and ferric ions in the lattice sites 53 .…”

The complex nonstoichiometry of wüstite Fe1-O: Review and comments

“…From a sample such as z  0.05, the disproportionation gives rise to Fe 0.918 O (defect rich phase P') and Fe 0.976 O (defect poor phase P), because of a mixture of the (13:4) and (4:1) clusters. Among numerous other Mössbauer studies reviewed by Long and Grandjean [15], Romanov, Checherskaya and Tatsienko [85] [86], Hrynkiewicz et al [87], Pattek-Janczyk et al [88], this latter is of particular interest. The authors modeled the asymmetric doublet with a singlet attributed to Fe 3+ in tetrahedral sites, and two doublets attributed to octahedral Fe 2+ and Fe 3+ .…”

Oxidation and Disproportionation of Wüstite Studied by Mössbauer Spectroscopy

“…2, where the absorption spectrum of the Fe 1−δ O phase shows an asymmetric doublet, which has often been used for the characterization of Fe vacancy structures. [6][7][8][9][10][11][12][13][14][15][16][17] The fractional amounts of the three phases, Fe 1−δ O, α-Fe and Fe 3 O 4 , obtained by analyzing the Mössbauer spectra are plotted against the logarithm of the annealing time at a con- …”