Vibrational spectra of synthetic minerals of the alunite and crandallite type

Breitinger, Dietrich K.; Krieglstein, R.; Bogner, Andreas; Schwab, R.; Pimpl, T.; Mohr, J.; Schukow, H.

doi:10.1016/s0022-2860(96)09627-5

Cited by 38 publications

(14 citation statements)

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“…The corresponding peak in H 3 O-alunite shifts slightly toward lower energy and shows small shoulders at ~130 and 120 meV. The broad band from 60 to 120 meV in alunite can be assigned to Al-OH and S-OH motion and OHhindered rotations (Serna et al 1986, Breitinger et al 1997). This band is wider and its substructure is different in H 3 O-alunite.…”

Section: Resultsmentioning

confidence: 93%

“…Numerous crystallographic and spectroscopic studies have been devoted to the nonstoichiometry and the nature of the non-OH "H 2 O" in the alunite-jarosite structure (e.g., Parker 1962, Brophy & Sheridan 1965, Kubisz 1972, Wilkins et al 1974, Serna et al 1986, Ripmeester et al 1986, Stoffregen & Alpers 1992, Breitinger et al 1997. Both synthetic and natural samples are known to contain H 2 O in excess of the stoichiometric amount.…”

Section: Nonstoichiometry and The Presence Of Non-oh "H 2 O"mentioning

confidence: 99%

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Neutron Spectroscopic Study of Synthetic Alunite and Oxonium-Substituted Alunite

Lager¹,

Swayze²,

Loong³

et al. 2001

The Canadian Mineralogist

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Synthetic, polycrystalline samples of alunite [K 0.88 (H 3 O) ] have been investigated using incoherent, inelastic neutron-scattering (IINS) methods in order to determine the nature of the non-OH "H 2 O". IINS measurements were made on non-deuterated samples at 20 K using the HRMECS chopper spectrometer with 250 and 600 meV incident energies. Alunite and oxonium-substituted alunite exhibit similar spectral features over the energy range of 120-550 meV, where assignments for local vibrations can be made based on the presence of OH and H 2 O groups. Salient differences in the intensities and positions of the observed low-energy vibrational bands reflect the effects of chemical substitution on the structural environment of the monovalent cation site and neighboring Al and OH sites in the framework.

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Section: Resultsmentioning

confidence: 93%

Section: Nonstoichiometry and The Presence Of Non-oh "H 2 O"mentioning

confidence: 99%

Neutron Spectroscopic Study of Synthetic Alunite and Oxonium-Substituted Alunite

Lager¹,

Swayze²,

Loong³

et al. 2001

The Canadian Mineralogist

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“…The relatively narrow hydroxyl stretch absorption (m OH ) is located near 2.95 lm, the m 3 stretch doublet of SO 4 2À is centered near 8.7 lm, the Fe-O-H in-planebend (d OH ) is positioned near 9.9 lm, and the narrow shoulder on the long wavelength side of the d OH bend is the m 1 stretch of SO 4 2À (Serna et al, 1986). There is some uncertainty regarding the assignment of absorptions at 15.0 lm to the m 4 stretch of SO 4 2À and at 22.3 lm to the m 2 stretch of SO 4 2À as these absorptions may be due to Fe-O related vibrations similar to the m Fe-O doublet absorption centered near 20 lm (Breitinger et al, 1997). The weak absorption near 17.1 lm belongs to the out-of-plane Fe-O-H bend (c OH ) based on observations of a deuterated synthetic jarosite (Serna et al, 1986), whereas the less intense absorption near 6 lm is due to the H-O-H bend in water (d H2O ) (Bishop and Murad, 2005).…”

Section: Spectroscopymentioning

confidence: 99%

“…Transmission spectra of end-member jarosite and natrojarosite and a natural mixture of these two end-members. Vibrational assignments are based on those given in Serna et al (1986), Breitinger et al (1997), and Bishop and Murad (2005). Dashed box (A) encompasses an absorption complex attributed to OH À and SO 4 À2 related absorptions shown in more detail in Fig.…”

Section: Spectroscopymentioning

confidence: 99%

Mineralogical and chemical characteristics of some natural jarosites

Desborough

Smith

Lowers

et al. 2010

Geochimica et Cosmochimica Acta

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This paper presents a detailed study of the mineralogical, microscopic, thermal, and spectral characteristics of jarosite and natrojarosite minerals. Systematic mineralogic and chemical examination of a suite of 32 natural stoichiometric jarosite and natrojarosite samples from diverse supergene and hydrothermal environments indicates that there is only limited solid solution between Na and K at low temperatures, which suggests the presence of a solvus in the jarosite-natrojarosite system at temperatures below about 140°C. The samples examined in this study consist of either end members or coexisting end-member pairs of jarosite and natrojarosite. Quantitative electron-probe microanalysis data for several natural hydrothermal samples show only end-member compositions for individual grains or zones, and no detectable alkali-site deficiencies, which indicates that there is no hydronium substitution within the analytical uncertainty of the method. In addition, there is no evidence of Fe deficiencies in the natural hydrothermal samples. Hydronium-bearing jarosite was detected in only one relatively young supergene sample suggesting that terrestrial hydronium-bearing jarosites generally are unstable over geologic timescales.Unit-cell parameters of the 20 natural stoichiometric jarosites and 12 natural stoichiometric natrojarosites examined in this study have distinct and narrow ranges in the a-and c-cell dimensions. There is no overlap of these parameters at the 1r level for the two end-member compositions. Several hydrothermal samples consist of fine-scale (2-10 lm) intimate intergrowths of jarosite and natrojarosite, which could have resulted from solid-state diffusion segregation or growth zoning due to variations in the Na/K activity ratio of hydrothermal solutions. Published by Elsevier Ltd.

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“…As hydronium cannot be detected using standard techniques, such as electron microprobe analysis, many researchers have attempted to prove its existence in the alunite or jarosite structure using vibrational, NMR, and other spectroscopic methods (Ripmeester et al 1986;Breitinger et al 1997;Lager et al 2001;Nielsen et al 2007, 2008 andreferences therein). Despite all of this effort, uncertainty regarding the nature and precise orientation of hydronium in alunite still exists.…”

Section: Introductionmentioning

confidence: 99%

A first-principles determination of the orientation of H3O+ in hydronium alunite

Gale

Wright

Hudson‐Edwards

2010

American Mineralogist

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The existence or otherwise of the hydronium cation within the mineral alunite has proved difficult to verify based on experimental data alone. In the present study, we employ first-principles quantum mechanical techniques to determine the nature of the structure of hydronium alunite. A new model for the hydrogen atom disorder is predicted that differs from a proposed arrangement in the case of the analogous stoichiometric hydronium jarosite. Instead of occupying one of two orientations that respect the threefold symmetry axis passing through the oxygen, the cation is found to occupy a tilted orientation leading to a greater degree of disorder. Dynamical simulations indicate that the reorientation of the hydronium ions is rapid and exhibits no correlation between the cation sites. The higher level of disorder in the hydrogen positions offers an explanation as to why their location has proved elusive thus far.

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Vibrational spectra of synthetic minerals of the alunite and crandallite type

Cited by 38 publications

References 0 publications

Neutron Spectroscopic Study of Synthetic Alunite and Oxonium-Substituted Alunite

Neutron Spectroscopic Study of Synthetic Alunite and Oxonium-Substituted Alunite

Mineralogical and chemical characteristics of some natural jarosites

A first-principles determination of the orientation of H3O+ in hydronium alunite

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