Raman spectroscopy of three polymorphs of BiVO₄: clinobisvanite, dreyerite and pucherite, with comparisons to (VO₄)³‐bearing minerals: namibite, pottsite and schumacherite

Abstract

Both Raman and infrared spectroscopy have been used to characterise the three phase-related minerals -dreyerite (tetragonal BiVO 4 ), pucherite (orthorhombic BiVO 4 ) and clinobisvanite (monoclinicBiVO 4 ) -and a comparison of the spectra is made with that of the minerals namibite (Cu(BiO 2 )VO 4 (OH)), schumacherite (Bi 3 O(OH)(VO 4 ) 2 ) and pottsite (PbBiH(VO 4 ) 2 ·2H 2 O). Pucherite, clinobisvanite and namibite are characterised by VO 4 stretching vibrations at 872, 824 and 846 cm −1 . The Raman spectrum of dreyerite shows complexity in the 750 to 950 cm −1 region with two intense bands at 836 and 790 cm −1 assigned to the symmetric and antisymmetric VO 4 modes. The minerals schumacherite and pottsite are characterised by bands at 846 and 874 cm −1 . In both the infrared and Raman, spectra bands are observed in the 1000-1100 cm −1 region which are attributed to the antisymmetric stretching modes. The Raman spectra of the low wavenumber region are complex. Bands are identified in the 328 to 370 cm −1 region and in the 404 to 498 cm −1 region and are assigned to the n 2 and n 4 bending modes. The minerals namibite and schumacherite are characterised by intense bands at 3514 and 3589 cm −1 assigned to the symmetric stretching vibrations of the OH units. Importantly, Raman spectroscopy enables new insights into the chemistry of these bismuth vanadate minerals. Raman spectroscopy enables the identification of the bismuth vanadate minerals in mineral matrices where paragenetic relationships exist between the minerals.

Thermal analysis of smithsonite and hydrozincite

“…In order to ensure that the correct spectra are obtained, the incident excitation radiation was scrambled. Previous studies by the authors provide more details of the experimental technique [11,12,15,17,[41][42][43][44][45][46][47].…”

“…Raman spectroscopy has proven very useful for the study of minerals [11][12][13]. Indeed Raman spectroscopy has proven most useful for the study of diagenetically related minerals such as carbonates and hydroxycarbonate [14][15][16][17][18].…”

“…Indeed Raman spectroscopy has proven most useful for the study of diagenetically related minerals such as carbonates and hydroxycarbonate [14][15][16][17][18]. Some previous studies have been undertaken by the authors using Raman spectroscopy to study complex secondary minerals formed by crystallisation from concentrated sulphate solutions [12][13][14][15][16][17][18][19][20][21]. Further hot stage Raman spectroscopy is most useful for the study of the thermal decomposition of minerals [22][23][24][25][26][27].…”

Raman spectroscopic study of the uranyl carbonate mineral voglite

“…[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Raman spectroscopy has proven most useful for the study of diagentically related minerals as often occurs with carbonate minerals. [30][31][32][34][35][36][37] No detailed Raman spectroscopic studies of the uranyl mineral voglite has been forth coming.…”

Photocatalytic properties of BiVO4 synthesized by microwave-assisted hydrothermal method under simulated sunlight irradiation

“…BiVO 4 photocatalysts have gained interest due to suitable visible light-induced energy band structure. In BiVO 4 polymorphs exist three crystal forms including monoclinic scheelite, tetragonal scheelite, and tetragonal zircon [19][20][21]. Among the three crystal type structures of BiVO 4 , monoclinic exhibits much higher photocatalytic activity than the other two tetragonal phases [22,23].…”