Abstract
Raman spectra were collected for synthetic gypsum (CaSO4⋅2H2O) powder between 9 and 373 K under atmospheric pressure with special emphasis on the temperature dependence of the OH-stretching modes. The stretching bands of the water molecules in gypsum were found to shift in opposite directions as a result of the different degree of intermolecular hydrogen-bonding between nonequivalent water H atoms and the O atoms of nearby SO4 ions. The anharmonic parameters of the OH-stretching modes are calculated using the temperature derivatives measured from the present investigation and existing pressure derivatives. These parameters are -4.7 × 10-6 K-1 and -0.6 × 10-6 K-1 for the 3407 and 3494 cm-1 bands, respectively. The dehydration of gypsum into γ-CaSO4 and the subsequent rehydration of γ-CaSO4 into hemihydrate are clearly identified in the Raman spectra by the observed variation in Raman shifts of the OH and ν1(SO4) bands. The latter increases as the mineral becomes increasingly anhydrous (1007 cm-1 in gypsum; 1014 cm-1 in hemihydrate; 1026 cm-1 in γ-CaSO4), which can be used as a fingerprint for the remote detection of these minerals on planetary surfaces.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Composition and I4/m-P42/n phase transition in scapolite solid solutions
- Synthesis and characterization of K2Ca5(SO4)6·H2O, the equivalent of görgeyite, a rare evaporite mineral
- Phase relations in the system Fe-FeSi at 21 GPa
- The speciation of dissolved H2O in dacitic melt
- Nucleation and growth kinetics of the α-β transformation in Mg2SiO4determined by in situ synchrotron powder X-ray diffraction
- Experimental determination of siderite stability and application to Martian Meteorite ALH84001
- Determination of the molar absorption coefficient for the infrared absorption band of CO2in rhyolitic glasses
- Crystallographic properties of the calcium phosphate mineral, brushite, by means of First Principles calculations
- The crystal structure of jonesite, Ba2(K,Na)[Ti2(Si5Al)O18(H2O)](H2O)n: A first example of titanosilicate with porous double layers
- Crystal-chemistry of talc: A near infrared (NIR) spectroscopy study
- Synthesis of beryllian sapphirine in the system MgO-BeO-Al2O3-SiO2-H2O and comparison with naturally occurring beryllian sapphirine and khmaralite, Part 2: A chemographic study of Be content as a function of P, T, assemblage and FeMg–1exchange
- Spriggite, Pb3[(UO2)6O8(OH)2](H2O)3, a new mineral with β-U3O8–type sheets: Description and crystal structure
- Sieve-textured plagioclase in dacitic magma: Interference imaging results
- Single crystal raman spectroscopy of cerussite
- Sodalite: High-temperature structures obtained from synchrotron radiation and Rietveld refinements
- The structure of metahohmannite, Fe3+2[O(SO4)2]⋅4H2O, by in situ synchrotron powder diffraction
- High-pressure synchrotron X-ray diffraction study of spessartine and uvarovite: A comparison between different equation of state models
- Quantum calculations of the electronic structure and NMR quadrupolar interaction parameters for tugtupite
- Identification of pyrite valence band contributions using synchrotron-excited X-ray photoelectron spectroscopy
- Micro-Raman studies of gypsum in the temperature range between 9 K and 373 K
- A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination?
- Structural variations in the brownmillerite series Ca2(Fe2–xAlx)O5: Single-crystal X-ray diffraction at 25 °C and high-temperature X-ray powder diffraction (25 °C ≤ T ≤ 1000 °C)
- Peculiarity and defect structure of the natural and synthetic zeolite mordenite: A single-crystal X-ray study
- Model independent phase equilibrium constraints on the ferrosilite activity in the binary Fe-Mg orthopyroxene solid solution
- Microstructural study of synthetic sintered diamond and comparison with carbonado, a natural polycrystalline diamond
- Structural and chemical response to varying [4]B content in zoned Fe-bearing olenite from Koralpe, Austria
- A new dense silica polymorph: A possible link between tetrahedrally and octahedrally coordinated silica
- Epitaxial relationships of clinopyroxene-hosted magnetite determined using electron backscatter diffraction (EBSD) technique