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1.
The mixed anion mineral parnauite Cu9[(OH)10|SO4|(AsO4)2]·7H2O has been studied by Raman spectroscopy. Characteristic bands associated with arsenate, sulphate and hydroxyl units are identified. Broad bands are observed and are resolved into component bands. Two intense bands at 859 and 830 cm−1 are assigned to the ν1 (AsO4)3− symmetric stretching and ν3 (AsO4)3− antisymmetric stretching modes. The comparatively sharp band at 976 cm−1 is assigned to the ν1 (SO4)2− symmetric stretching mode and a broad‐spectral profile centered upon 1097 cm−1 is attributed to the ν3 (SO4)2− antisymmetric stretching mode. A comparison of the Raman spectra is made with other arsenate‐bearing minerals such as carminite, clinotyrolite, kankite, tilasite and pharmacosiderite. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

2.
The Raman spectrum of bukovskýite [Fe3+2(OH)(SO4)(AsO4)· 7H2O] has been studied and compared with that of an amorphous gel containing specifically Fe, As and S, which is understood to be an intermediate product in the formation of bukovskýite. The observed bands are assigned to the stretching and bending vibrations of (SO4)2− and (AsO4)3− units, stretching and bending vibrations and vibrational modes of hydrogen‐bonded water molecules, stretching and bending vibrations of hydrogen‐bonded (OH) ions and Fe3+ (O,OH) units. The approximate range of O H···O hydrogen bond lengths was inferred from the Raman spectra. Raman spectra of crystalline bukovskýite and of the amorphous gel differ in that the bukovskýite spectrum is more complex, the observed bands are sharp and the degenerate bands of (SO4)2− and (AsO4)3− are split and more intense. Lower wavenumbers of δ H2O bending vibrations in the spectrum of the amorphous gel may indicate the presence of weaker hydrogen bonds compared to those in bukovskýite. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

3.
Raman spectrum of burgessite, Co2(H2O)4[AsO3OH]2· H2O, was studied, interpreted and compared with its infrared spectrum. The stretching and bending vibrations of (AsO3) and As‐OH units, as well as the stretching, bending and libration modes of water molecules and hydroxyl ions were assigned. The range of O H···O hydrogen bond lengths was inferred from the Raman and infrared spectra of burgessite. The presence of (AsO3OH)2− units in the crystal structure of burgessite was proved, which is in agreement with its recently solved crystal structure. Raman and infrared spectra of erythrite inferred from the RRUFF database are used for comparison. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

4.
The removal of arsenate anions from aqueous media, sediments and wasted soils is of environmental significance. The reaction of gypsum with the arsenate anion results in pharmacolite mineral formation, together with related minerals. Raman and infrared (IR) spectroscopy have been used to study the mineral pharmacolite Ca(AsO3OH)· 2H2O. The mineral is characterised by an intense Raman band at 865 cm−1 assigned to the ν1 (AsO3)2− symmetric stretching mode. The equivalent IR band is found at 864 cm−1. The low‐intensity Raman bands in the range from 844 to 886 cm−1 provide evidence for ν3 (AsO3) antisymmetric stretching vibrations. A series of overlapping bands in the 300‐450 cm−1 region are attributed to ν2 and ν4 (AsO3) bending modes. Prominent Raman bands at around 3187 cm−1 are assigned to the OH stretching vibrations of hydrogen‐bonded water molecules and the two sharp bands at 3425 and 3526 cm−1 to the OH stretching vibrations of only weakly hydrogen‐bonded hydroxyls in (AsO3OH)2− units. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

5.
Raman spectroscopy has been used to study the arsenate minerals haidingerite Ca(AsO3OH)·H2O and brassite Mg(AsO3OH)·4H2O. Intense Raman bands in the haidingerite spectrum observed at 745 and 855 cm−1 are assigned to the (AsO3OH)2−ν3 antisymmetric stretching and ν1 symmetric stretching vibrational modes. For brassite, two similarly assigned intense bands are found at 809 and 862 cm−1. The observation of multiple Raman bands in the (AsO3OH)2− stretching and bending regions suggests that the arsenate tetrahedrons in the crystal structures of both minerals studied are strongly distorted. Broad Raman bands observed at 2842 cm−1 for haidingerite and 3035 cm−1 for brassite indicate strong hydrogen bonding of water molecules in the structure of these minerals. OH···O hydrogen‐bond lengths were calculated from the Raman spectra based on empirical relations. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

6.
The mineral dussertite, a hydroxy‐arsenate mineral with formula BaFe3+3(AsO4)2(OH)5, has been studied by Raman spectroscopy complemented with infrared spectroscopy. The spectra of three minerals from different origins were investigated and proved to be quite similar, although some minor differences were observed. In the Raman spectra of the Czech dussertite, four bands are observed in the 800–950 cm−1 region. The bands are assigned as follows: the band at 902 cm−1 is assigned to the (AsO4)3−ν3 antisymmetric stretching mode, the one at 870 cm−1 to the (AsO4)3−ν1 symmetric stretching mode, and those at 859 and 825 cm−1 to the As‐OM2 + /3+ stretching modes and/or hydroxyl bending modes. Raman bands at 372 and 409 cm−1 are attributed to the ν2 (AsO4)3− bending mode and the two bands at 429 and 474 cm−1 are assigned to the ν4 (AsO4)3− bending mode. An intense band at 3446 cm−1 in the infrared spectrum and a complex set of bands centred upon 3453 cm−1 in the Raman spectrum are attributed to the stretching vibrations of the hydrogen‐bonded (OH) units and/or water units in the mineral structure. The broad infrared band at 3223 cm−1 is assigned to the vibrations of hydrogen‐bonded water molecules. Raman spectroscopy identified Raman bands attributable to (AsO4)3− and (AsO3OH)2− units. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

7.
Raman spectra of natrouranospinite complemented with infrared spectra were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3− units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

8.
Raman spectra of metauranospinite Ca[(UO2)(AsO4)]2·8H2O complemented with infrared spectra were studied. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3− units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

9.
The mineral ardealite Ca2(HPO4)(SO4)·4H2O is a ‘cave’ mineral and is formed through the reaction of calcite with bat guano. The mineral shows disorder and the composition varies depending on the origin of the mineral. Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the mineral ardealite. The Raman spectrum is very different from that of gypsum. Bands are assigned to SO42− and HPO42− stretching and bending modes. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

10.
Raman spectroscopy has been used to study selected mineral samples of the copiapite group. Copiapite (Fe2+Fe3+(SO4)6(OH)2 · 20H2O) is a secondary mineral formed through the oxidation of pyrite. Minerals of the copiapite group have the general formula AFe4(SO4)6(OH)2 · 20H2O, where A has a + 2 charge and can be either magnesium, iron, copper, calcium and/or zinc. The formula can also be B2/3Fe4(SO4)6(OH)2 · 20H2O, where B has a + 3 charge and may be either aluminium or iron. For each mineral, two Raman bands are observed at around 992 and 1029 cm−1, assigned to the (SO4)2−ν1 symmetric stretching mode. The observation of two bands provides evidence for the existence of two non‐equivalent sulfate anions in the mineral structure. Three Raman bands at 1112, 1142 and 1161 cm−1 are observed in the Raman spectrum of copiapites, indicating a reduction of symmetry of the sulfate anion in the copiapite structure. This reduction in symmetry is supported by multiple bands in the ν2 and ν4(SO4)2− spectral regions. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

11.
Raman spectra of two well‐defined types of koritnigite crystals from the Jáchymov ore district, Czech Republic, were recorded and interpreted. No substantial differences were observed between both crystal types. The observed Raman bands were attributed to the (AsO3OH)2− stretching and bending vibrations as well as stretching and bending vibrations of water molecules and hydroxyl ions. The non‐interpreted Raman spectra of koritnigite from the RRUFF database and the published infrared spectra of cobaltkoritnigite were used for comparison. The O H···O hydrogen bond lengths in the crystal structure of koritnigite were inferred from the Raman spectra and compared with those derived from the X‐ray single‐crystal refinement. The presence of (AsO3OH)2− units in the crystal structure of koritnigite was proved from the Raman spectra, which supports the conclusions of the X‐ray structure analysis. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
The mixed anion mineral dixenite has been studied by Raman spectroscopy, complemented with infrared spectroscopy. The Raman spectrum of dixenite shows bands at 839 and 813 cm−1 assigned to the (AsO3)3− symmetric and antisymmetric stretching modes. The most intense Raman band of dixenite is the band at 526 cm−1 and is assigned to the ν2 AsO33− bending mode. DFT calculations enabled the calculation of the position of AsO22− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1, and the deformation mode at 449 cm−1. The Raman bands at 1026 and 1057 cm−1 are assigned to the SiO42− symmetric stretching vibrations and those at 1349 and 1386 cm−1 to the SiO42− antisymmetric stretching vibrations. Both Raman and infrared spectra indicate the presence of water in the structure of dixenite. This brings into question the commonly accepted formula of dixenite as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6. The formula may be better written as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6·xH2O. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

13.
The selected arsenite minerals leiteite, reinerite and cafarsite have been studied by Raman spectroscopy. Density functional theory (DFT) calculations enabled the position of the AsO22− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1 and the deformation mode at 449 cm−1 to be calculated. The Raman spectrum of leiteite shows bands at 804 and 763 cm−1 assigned to the As2O42− symmetric and antisymmetric stretching modes. The most intense Raman band of leiteite is the band at 457 cm−1 and is assigned to the ν2 As2O42− bending mode. A comparison of the Raman spectrum of leiteite is made with the arsenite minerals reinerite and cafarsite. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

14.
Raman spectroscopy has been used to study the rare‐earth mineral churchite‐(Y) of formula (Y,REE)(PO4) ·2H2O, where rare‐earth element (REE) is a rare‐earth element. The mineral contains yttrium and, depending on the locality, a range of rare‐earth metals. The Raman spectra of two churchite‐(Y) mineral samples from Jáchymov and Medvědín in the Czech Republic were compared with the Raman spectra of churchite‐(Y) downloaded from the RRUFF data base. The Raman spectra of churchite‐(Y) are characterized by an intense sharp band at 975 cm−1 assigned to the ν1 (PO43−) symmetric stretching mode. A lower intensity band observed at around 1065 cm−1 is attributed to the ν3 (PO43−) antisymmetric stretching mode. The (PO43−) bending modes are observed at 497 cm−12) and 563 cm−14). Some small differences in the band positions between the four churchite‐(Y) samples from four different localities were found. These differences may be ascribed to the different compositions of the churchite‐(Y) minerals. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

15.
The two minerals diadochite and destinezite of formula Fe2(PO4,SO4)2(OH)· 6H2O have been characterised by Raman spectroscopy and complemented with infrared spectroscopy. Both these minerals are found in soils and are identical except for their morphology. Diadochite is amorphous whereas destinezite is highly crystalline. The spectra of diadochite are broad and ill defined, whereas the spectra of destinezite are intense and well defined. Bands are assigned to phosphate and sulfate stretching and bending modes. Two symmetric stretching modes for both phosphate and sulfate support the concept of non‐equivalent phosphate and sulfate units in the mineral structure. Multiple water bending and stretching modes imply that non‐equivalent water molecules in the structure exist with different hydrogen‐bond strengths. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

16.
The participation of hydrogen‐arsenate group (AsO3OH)2− in solid‐state compounds may serve as a model example for explaining and clarifying the behaviour of As and other elements during weathering processes in natural environment. The mineral geminite, a hydrated hydrogen‐arsenate mineral of ideal formula Cu(AsO3OH)·H2O, has been studied by Raman and infrared spectroscopies. Two samples of geminite of different origin were investigated and the spectra proved quite similar. In the Raman spectra of geminite, six bands are observed at 741, 812, 836, 851, 859 and 885 cm−1 (Salsigne, France), and 743, 813, 843, 853, 871 and 885 cm−1 (Jáchymov, Czech Republic). The band at 851/853 cm−1 is assigned to the ν1 (AsO3OH)2− symmetric stretching mode; the other bands are assigned to the ν3 (AsO3OH)2− split triply degenerate antisymmetric stretching mode. Raman bands at 309, 333, 345 and 364/310, 333 and 345 cm−1 are attributed to the ν2 (AsO3OH)2− bending mode, and a set of higher wavenumber bands (in the range 400–500 cm−1) is assigned to the ν4 (AsO3OH)2− split triply degenerate bending mode. A very complex set of overlapping bands is observed in both the Raman and infrared spectra. Raman bands are observed at 2289, 2433, 2737, 2855, 3235, 3377, 3449 and 3521/2288, 2438, 2814, 3152, 3314, 3448 and 3521 cm−1. Two Raman bands at 2289 and 2433/2288 and 2438 cm−1 are ascribed to the strong hydrogen bonded water molecules. The Raman bands at 3235, 3305 and 3377/3152 and 3314 cm−1 may be assigned to the ν OH stretching vibrations of water molecules. Two bands at 3449 and 3521/3448 and 3521 cm−1 are assigned to the OH stretching vibrations of the (AsO3OH)2− units. The lengths of the O H···O hydrogen bonds vary in the range 2.60–2.94 Å (Raman) and 2.61–3.07 Å (infrared). Two Raman and infrared bands in the region of the bending vibrations of the water molecules prove that structurally non‐equivalent water molecules are present in the crystal structure of geminite. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
Three crystalline ferric arsenate phases: (1) scorodite; FeAsO4·2H2O, (2) ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and (3) basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)xwH2O) synthesized by hydrothermal precipitation (175–225 °C) from Fe(III)‐AsO43−–SO42− solutions have been investigated via Raman and infrared spectroscopies. The spectroscopic nature of these high‐temperature Fe(III)‐ AsO43−–SO42− phases has not been extensively studied despite their importance to the hydrometallurgical industrial processing of precious metal (Au and Cu) arsenic sulfidic ores. It was found that scorodite, FAsH and BFAS all gave rise to very distinct arsenate, sulfate and hydroxyl vibrations. In scorodite and FAsH, the distribution of the internal arsenate modes was found to be distinct, with the factor effect being more predominant in the crystal system. For the crystallographically unknown BFAS phase, vibrational spectroscopy was used to monitor the arsenate ↔ sulfate solid solution behavior that occurs in this phase where the molecular symmetry of arsenate and sulfate in the crystal structure is reduced from an ideal Td to a distorted Td or C2/C2v symmetry. With the new collected vibrational data of the pure phases, the use of attenuated total reflectance infrared (ATR‐IR) spectroscopy was finally extended to investigate the nature of the arsenate in an industrial residue generated by pressure oxidation of a gold ore, where it was found that the arsenate was present in the form of BFAS. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

18.
Raman spectra of brandholzite Mg[Sb2(OH)12]·6H2O were studied, complemented with infrared spectra, and related to the structure of the mineral. An intense Raman sharp band at 618 cm−1 is attributed to the SbO symmetric stretching mode. The low‐intensity band at 730 cm−1 is ascribed to the SbO antisymmetric stretching vibration. Low‐intensity Raman bands were found at 503, 526 and 578 cm−1. Corresponding infrared bands were observed at 527, 600, 637, 693, 741 and 788 cm−1. Four Raman bands observed at 1043, 1092, 1160 and 1189 cm−1 and eight infrared bands at 963, 1027, 1055, 1075, 1108, 1128, 1156 and 1196 cm−1 are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3240, 3383, 3466, 3483 and 3552 cm−1; infrared bands at 3248, 3434 and 3565 cm−1. The Raman bands at 3240 and 3383 cm−1 and the infrared band at 3248 cm−1 are assigned to water‐stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm−1 and two infrared bands at 3434 and 3565 cm−1 are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands in the OH stretching region are associated with O‐H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

19.
Raman microscopy of the mixite mineral BiCu6(AsO4)3(OH)6·3H2O from Jáchymov and from Smrkovec (both Czech Republic) has been used to study their molecular structure. The presence of (AsO4)3−, (AsO3OH)2−, (PO4)3− and (PO3OH)2− units, as well as molecular water and hydroxyl ions, was inferred. O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra using Libowitzky's empirical relation. Small differences in the Raman spectra between both samples were observed and attributed to compositional and hydrogen‐bonding network differences. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

20.
The mineral wheatleyite has been synthesised and characterised by Raman spectroscopy complimented with infrared spectroscopy. Two Raman bands at 1434 and 1470 cm−1 are assigned to the ν(C O) stretching mode and implies two independent oxalate anions. Two intense Raman bands observed at 904 and 860 cm−1 are assigned to the ν(C C) stretching mode and support the concept of two non‐equivalent oxalate units in the wheatleyite structure. Two strong bands observed at 565 and 585 cm−1 are assigned to the symmetric CCO in plane bending modes. The Raman band at 387 cm−1 is attributed to the CuO stretching vibration and the bands at 127 and 173 cm−1 to OCuO bending vibrations. A comparison is made with Raman spectra of selected natural oxalate bearing minerals. Oxalates are markers or indicators of environmental events. Oxalates are readily determined by Raman spectroscopy. Thus, deterioration of works of art, biogeochemical cycles, plant metal complexation, the presence of pigments and minerals formed in caves can be analysed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

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