Theoretical and experimental study of the vibrational spectra of (para)symplesite and hörnesite

Makreski, Petre; Stefov, Stefan; Pejov, Ljupčo; Jovanovski, Gligor

doi:10.1016/j.saa.2015.01.108

Cited by 26 publications

(19 citation statements)

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“…Hydrogen atoms could not be located, but strong hydrogen bonding network can be assumed based on the close distances between the oxygen atoms of the H 2 O/HO – and AsO 4 3– groups. Recently published results on the vibrational spectra of this mineral confirm the presence of strong hydrogen bonding 6…”

Section: Resultsmentioning

confidence: 62%

“…The search for single crystals suitable for single crystal diffraction failed, as the sample particles were in form of irregular microcrystals (Figure 1). Prior to XRPD data collection, IR and Raman spectra were collected on the same powdered material and indicated phase purity (the spectra were recently published as part of a comparative vibrational study of symplesite and hörnesite) 6…”

Section: Resultsmentioning

confidence: 99%

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The Crystal Structure of Symplesite

Runčevski

Makreski

Dinnebiér

et al. 2015

Zeitschrift anorg allge chemie

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Since the discovery of symplesite mineral in the late 19th century, a number of structural studies were performed. The crystal symmetry of this mineral was debated to be either monoclinic or triclinic. Even though this debate has ended, agreeing on the triclinic symmetry, no detailed crystal structure was reported so far. In the present contribution, we report on the crystal structure of symplesite. The crystal structure was solved and refined from high‐resolution laboratory X‐ray powder diffraction data, collected on a natural sample. Symplesite is shown to be isostructural to metavivianite (and possibly to ferrostrunzite).

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Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

The Crystal Structure of Symplesite

Runčevski

Makreski

Dinnebiér

et al. 2015

Zeitschrift anorg allge chemie

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“…The bands at 653 cm −1 (pharmacolite), 675 and 653 cm −1 (vladimirite), and 675 and 653 cm −1 (picropharmacolite) are attributed to crystalline water librational modes (Table ) …”

Section: Resultsmentioning

confidence: 99%

“…As continuation of our spectra‐structural studies on various rare arsenate minerals, herein, we report the analysis of the theoretical and experimental vibrational spectra of the secondary and very complex arsenate and hydrogen arsenate hydrous minerals—vladimirite, picropharmacolite, and pharmacolite.…”

Section: Introductionmentioning

confidence: 99%

Vibrational spectra of the rare‐occurring complex hydrogen arsenate minerals pharmacolite, picropharmacolite, and vladimirite: Dominance of Raman over IR spectroscopy to discriminate arsenate and hydrogen arsenate units

Makreski

Todorov

Makrievski

et al. 2018

J Raman Spectroscopy

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This work represents the first complete experimental and theoretical study of the infrared (IR) spectra of pharmacolite, Ca(AsO3OH)·2H2O; vladimirite, Ca4(AsO3OH)(AsO4)2·4H2O; and picropharmacolite, Ca4Mg(AsO3OH)2(AsO4)2·11H2O. IR spectra, collected at both room and liquid nitrogen temperature, have shown similar spectral view among minerals in the region of ν1 to ν4 modes, surprisingly not involving complexity in vladimirite and picropharmacolite spectral view due to the presence of both AsO3OH and AsO4 units compared to pharmacolite where only AsO3OH units appear in the structure. On the other hand, vladimirite and picropharmacolite Raman spectra in the corresponding ν1 to ν4 region (955–350 cm−1) exhibit existence of 3 sets of 2 bands (6 in total) completely reflecting the existence of 3 symmetrically nonequivalent AsO4 groups in the structures of vladimirite and picropharmacolite (of which one is protonated) and only one set of ν1 to ν4 bands from the structurally equivalent AsO3OH units in the pharmacolite structure. The liquid nitrogen temperature IR spectra enabled to infer important information regarding the OH vibrational bands related to the AsO3OH groups and to the water molecules. Essentially, all bands in the vibrational spectra were assigned and correlated with the findings for a plethora of structurally similar complex hydrogen arsenate minerals. To support the tentative assignment of bands in the vibrational spectra, quantum theoretical calculations were performed within the framework of density functional theory. On the basis of theoretical calculations, a few reassignments of bands appearing in the OH stretching region are proposed. X‐ray powder diffraction was used to confirm authenticity of the title systems.

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“…Standard Eckart projection algorithm was used to project out the translations and rotations of the nuclear Hessians. The applied methodology was also used in our previous work for other arsenate-hydrates minerals, parasymplesite and hörnesite [22].…”

Section: Theoretical Modelmentioning

confidence: 99%