Mn-Substituted Goethite and Fe-Substituted Groutite Synthesized at Acid pH1
| Autor: | Darrell G. Schulze, M. H. Ebinger |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
Goethite
Chemistry Metallurgy Analytical chemistry Soil Science Hematite engineering.material Mole fraction Manganite chemistry.chemical_compound Geochemistry and Petrology visual_art Earth and Planetary Sciences (miscellaneous) visual_art.visual_art_medium engineering Biogeosciences Powder diffraction Hausmannite Water Science and Technology Groutite |
| Zdroj: | Clays and Clay Minerals. 37:151-156 |
| ISSN: | 0009-8604 |
| DOI: | 10.1346/ccmn.1989.0370206 |
| Popis: | Ahstract--Mn-substituted iron oxides were synthesized by coprecipitating Fe(NO3)3 and Mn(SO4) solutions with NH4OH, adjusting the suspensions to pH 4 or 6, and then keeping the suspensions at 55~ for 62 days. The Mn mole fraction of the final products ranged from 0 to 0.3. X-ray powder diffraction patterns showed that goethite and hematite formed in each Fe-containing system. Groutite formed in systems having initial Mn mole fractions ->0.35. Only manganite and hausmannite formed in the pure Mn systems. The oxalate-soluble Fe in the samples increased as the Mn mole fraction increased and was slightly larger for the pH 6 series. For samples that contained the largest Mn mole fraction, the b and c dimensions of the goethite unit cell were shifted toward those ofgroutite, and the b and c dimensions of the groutite unit cell were shifted toward those of goethite. Assuming the Vegard rule holds for the unit-cell c dimension, the goethite accommodated a maximum Mn mole fraction of 0.34, and the groutite accommodated a maximum Fe mole fraction of 0.31. The unit-cell dimensions of hematite did not vary systematically with the mole fraction of Mn in solution, probably because little Mn substituted into the hematite structure. |
| Databáze: | OpenAIRE |
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