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Article
Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite
Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between t...
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Article
Theoretical study of the local charge compensation and spectroscopic properties of B-type carbonate defects in apatite
The structure and spectroscopic properties of selected models of B-type carbonate defects in apatite locally compensated by fluoride or hydroxyl ions are investigated using first-principles quantum mechanical...
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Article
Infrared spectroscopic properties of goethite: anharmonic broadening, long-range electrostatic effects and Al substitution
The infrared spectrum and its temperature dependence (20–320 K) were collected on a synthetic goethite sample (α-FeOOH). In addition, the infrared powder absorption spectrum of goethite and aluminum-substitute...
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Article
Contribution of interstitial OH groups to the incorporation of water in forsterite
Water incorporation in forsterite samples synthesized under low to medium silica-activity conditions mostly occurs via a substitutional mechanism in which a Si vacancy is compensated by four protons. Correspo...
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Article
First-principles study of OH defects in zircon
The infrared spectroscopic properties of selected OH defects in zircon are investigated by first-principles calculations. The explicit treatment of the coupled nature of OH motions in the stretching modes, tog...
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Article
Theoretical study of OH-defects in pure enstatite
The infrared spectroscopic properties of selected defects in orthoenstatite are investigated by first-principles calculations. The considered defects include doubly protonated Mg vacancies at M1 and M2 sites, ...
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Article
Insights into the high-pressure behavior of kaolinite from infrared spectroscopy and quantum-mechanical calculations
The high-pressure behavior of Keokuk kaolinite has been studied to 9.5 GPa by infrared spectroscopy using synchrotron radiation. The kaolinite-I → kaolinite-II and kaolinite-II → kaolinite-III transformations ...
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Article
Experimental and theoretical study of the vibrational properties of diaspore (α-AlOOH)
Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy and low-temperature powder infrared (IR) transmission spectroscopy. First-princip...
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Article
V oxidation state in Fe–Ti oxides by high-energy resolution fluorescence-detected X-ray absorption spectroscopy
The oxidation state of vanadium in natural and synthetic Fe–Ti oxides is determined using high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS). Eleven natural magnetite-bearin...
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Article
Line-broadening effects in the powder infrared spectrum of apatite
The crystallinity of natural and synthetic apatite samples is often determined from the broadening of ν 4 PO4 infrared absorption bands. However, various physical mechanisms contribute to ...
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Article
Surface modes in the infrared spectrum of hydrous minerals: the OH stretching modes of bayerite
The theoretical infrared (IR) and Raman spectra of bayerite (β-Al(OH)3) are computed in the density functional theory framework, using the linear response theory. The results are consistent with the occurrence of...
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Article
Anharmonicity of inner-OH stretching modes in hydrous phyllosilicates: assessment from first-principles frozen-phonon calculations
The theoretical anharmonicity of the inner-OH stretching modes of kaolinite and lizardite is determined using a frozen-phonon approach. The anharmonicity parameter, defined as the difference between half the f...
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Article
Inheritance vs. neoformation of kaolinite during lateritic soil formation: A case study in the middle Amazon basin
The tropical weathering of sedimentary kaolin deposits from the plateaux surrounding Manaus (Alter do Chao formation, Amazon basin, Brazil) leads to the in situ formation of thick kaolinitic soils. The structural...
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Article
Radiation-induced Defects in Nonradioactive Natural Minerals: Mineralogical and Environmental Significance
Natural short-lived radionuclides generate electronic defects in minerals, such as trapped electrons and positive holes, often associated with element impurities, which act as final traps over geological perio...
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Article
Quantitative Measurement of Paramagnetic Fe3+ in Kaolinite
A method is proposed to measure the absolute concentration of paramagnetic Fe3+ ions in kaolinite from various geochemical environments using powder X-band electron paramagnetic resonance (EPR) data. An Fe3+-dope...
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Article
Structural Fe3+ in Natural Kaolinites: New Insights from Electron Paramagnetic Resonance Spectra Fitting at X and Q-Band Frequencies
Structural Fe3+ in kaolinites and dickites covering a broad range of disorder was investigated using electron paramagnetic resonance (EPR) spectroscopy at both the X and Q-band frequencies. A procedure based on a...
