Raman spectroscopic study of the arsenite mineral vajdakite [(Mo⁶⁺O₂)₂(H₂O)₂As³⁺₂O₅]·H₂O

Abstract

Raman spectra of vajdakite, [(Mo 6+ O 2 ) 2 (H 2 O) 2 As 3+ 2 O 5 ]·H 2 O, were studied and interpreted in terms of the structure of the mineral. The Raman spectra were compared with the published infrared spectrum of vajdakite. The presence of dimolybdenyl and diarsenite units and of hydrogen bonded water molecules was inferred from the Raman spectra which supported the known and published crystal structure of vajdakite. Mo-O and O-H· · ·O bond lengths were calculated from the Raman spectra.

Recent advances in linear and nonlinear Raman spectroscopy. Part V

“…Vibrational analyses of the following minerals have been carried out by Frost and coworkers using Raman scattering and other related techniques: the arsenite mineral finnemanite Pb 5 (As 3+ O 3 ) 3 Cl; the multi‐anion mineral dixenite, CuMn 2+ 14 Fe 3+( AsO 3 ) 5 (SiO 4 ) 2 (AsO 4 )(OH) 6 ; vajdakite, [(Mo 6+ O 2 ) 2 (H 2 O) 2 As 2 3+ O 5 ]‐H 2 O; triclinic cejkaite Na 4 [UO 2 (CO 3 ) 3 ] and its synthetic trigonal analog; the arsenite minerals leiteite ZnAs 2 O 4 , reinerite Zn 3 (AsO 3 ) 2 and cafarsite Ca 5 (Ti,Fe,Mn) 7 (AsO 3 ) 12 ‐4H 2 O; the antimonate mineral bahianite Al 5 Sb 5+ 3 O 14 (OH) 2 , a semi‐precious gemstone; the antimonate mineral bottinoite Ni[Sb 2 (OH) 12 ]‐6H 2 O and in comparison with brandholzite Mg[Sb 5+ 2 (OH) 12 ]‐6H 2 O; haidingerite Ca(AsO 3 OH)‐H 2 O and brassite Mg(AsO 3 OH)‐4H 2 O; the kaolinite‐like phyllosilicate minerals bismutoferrite BiFe 3+ 2 Si 2 O 8 (OH) and chapmanite SbFe 3+ 2 Si 2 O 8 (OH); the hydrogen‐arsenate mineral pharmacolite Ca(AsO 3 OH)‐2H 2 O with implications for aquifer and sediment remediation; the mineral gerstleyite Na 2 (Sb,As) 8 S 13 ‐2H 2 O and in comparison with some heavy‐metal sulfides; synthetic reevesite and cobalt substituted reevesite (Ni,Co) 6 Fe 2 (OH) 16 (CO 3 )‐4H 2 O; the mineral euchroite, a mineral involved in a complex set of equilibria between the copper hydroxy arsenates: euchroite Cu 2 (AsO 4 )(OH)‐3H 2 O‚ olivenite Cu 2 (AsO 4 )(OH)‚ strashimirite Cu 8 (AsO 4 ) 4 (OH) 4 ‐5H 2 O and arhbarite Cu 2 Mg(AsO 4 )(OH) 3 ; the mixite mineral BiCu 6 (AsO 4 ) 3 (OH) 6 ‐3H 2 O from the Czech Republic; the gallium‐based hydrotalcites of formula Mg 6 Ga 2 (CO 3 )(OH) 16 ‐4H 2 O; the indium‐based hydrotalcites of formula Mg6In 2 (CO 3 )(OH) 16 ‐4H 2 O; the hydroxy‐arsenate‐sulfate mineral chalcophyllite Cu 18 Al 2 (AsO 4 ) 4 (SO 4 ) 3 (OH) 24 ‐36H 2 O; the phosphate mineral churchite‐(Y) YPO 4 ‐2H2O; the synthesis of sodium hexatitanate from sodium trititanate was characterized by Raman spectroscopy, XRD and high‐resolution TEM; a Raman spectroscopic study on the allocation of ammonium‐adsorbing sites on H2Ti3O7 nanofibre and its structural derivation during calcination; and hydrogen‐arsenate group (AsO 3 OH) in solid‐state compounds: copper mineral phase geminite Cu(AsO 3 OH)‐H2O from different geological environments . Gomez et al .…”

Single-crystal Raman spectroscopy of natural paulmooreite Pb2As2O5 in comparison with the synthesized analog

“…Vajdakite, [(MoO 2 ) 2 (H 2 O) 2 As 2 O 5 ]•H 2 O, also possesses [As 2 O 5 ] 4-units (Ondrus et al 2002) and had been studied previously with Raman spectroscopy (Cejka et al 2010). However the presence of two non-equivalent MoO 5 (H 2 O) units makes it difficult to identify and assign the vibrations of the unit since there may be some coincidence of the bands.…”

A Raman spectroscopic study of the ‘cave’ mineral ardealite Ca2(HPO4)(SO4)·4H2O

“…Raman spectroscopy has proved very useful for the study of minerals 12–25. Indeed Raman spectroscopy has proved most useful for the study of diagentically related minerals as often occurs with minerals containing sulfate and phosphate groups.…”