Effect of Crystallinity and Al Substitution on the Applied‐Field Mössbauer Spectra of Iron Oxides and Oxyhydroxides

Abstract

Applied‐field Mössbauer spectra are reported for selected synthetic samples of α‐Fe1‐xAlxOOH, γ‐Fe1‐xAlxOOH, δ‐FeOOH, α‐(Fe1‐xAlx)2O3 and γ‐Fe2O3. Field strengths of up to 90 kOe were used at temperatures of mostly 4.2 K. The effects of the Al substitution and/or the crystallinity are discussed. Specific characteristics of the spectra are enlightened which might serve as complimentary sources of information for the characterization of soil oxides and oxyhydroxides. It is pointed out that several questions remain unanswered to date and that further systematic research is justified.

The influence of Zn-dopant on the precipitation of α-FeOOH in highly alkaline media

“…Specifically, this technique showed its potentials in the investigations of Al 3+ [20][21][22][23], Ga 3+ [24] and Sn 4+ [25] substitutions for Fe in ␣-FeOOH.…”

Influence of ruthenium ions on the precipitation of α-FeOOH, α-Fe2O3 and Fe3O4 in highly alkaline media

“…These measurements showed that the c-dimension was a linear function of Al substitution in the range 0-33 mol% Al, the a-dimension was variable over the same concentration range, whereas the b-dimension slightly deviated from linearity in the range 20-33 mol% Al. Mössbauer spectroscopy found important application in the investigation of Al-doped ␣-FeOOH [15][16][17][18][19].…”

Influence of Ni-dopant on the properties of synthetic goethite

“…Schulze [16] showed that in synthetic Al-substituted ␣-FeOOH crystallites the c-dimension was a linear function of Al-substitution between 0 and 33 mol% Al, the a-dimension varied over the same range, whereas the b-dimension was a linear function up to 20 mol% Al. Mössbauer spectroscopy found important application in the investigation of Al-doped ␣-FeOOH [17][18][19][20][21].…”