Raman spectroscopic study of the metatellurate mineral: xocomecatlite Cu₃TeO₄(OH)₄

Abstract

The mineral xocomecatlite is a hydroxy metatellurate mineral with Te 6+ O 4 units. Tellurates may be subdivided according to their formula into three types of tellurate minerals: type (a) (AB) m (TeO 4 ) p Z q , type (b) (AB) m (TeO 6 ) · xH 2 O and (c) compound tellurates in which a second anion including the tellurite anion, is involved. The mineral xocomecatlite is an example of the first type. Raman bands for xocomecatlite at 710, 763 and 796 cm −1 , and 600 and 680 cm −1 are attributed to the ν 1 (TeO 4 ) 2− symmetric and ν 3 antisymmetric stretching mode. Raman bands observed at 2867 and 2926 cm −1 are assigned to TeOH stretching vibrations and enable estimation of the hydrogen bond distances of 2.622 Å (2867 cm −1 ), 2.634 Å (2926 cm −1 ) involving these OH units. The hydrogen bond distances are very short implying that they are necessary for the stability of the mineral.

Peroxide Coordination of Tellurium in Aqueous Solutions

“…It was observed in hexahydroperoxostannates, peroxoantimonate, and peroxogermanate (865, 868, and 872–874 cm −1 , respectively), and it is attributed to the effect of the coordinating heavy atom. The other Raman lines in Figure S3 are less relevant; they are attributed to Te−O vibrations (lines below 800 cm −1 ) and to NH and OH vibrations (above 1000 cm −1 ) in accordance with a previous study of tellurates …”

“…The otherR aman lines in Figure S3 are less relevant;t hey are attributed to TeÀOv ibrations (lines below 800 cm À1 )a nd to NH and OH vibrations (above 1000 cm À1 )i na ccordance with ap revious study of tellurates. [23] TG and DSC studies…”

The crystal structure of cesbronite, Cu3TeO4(OH)4: a novel sheet tellurate topology

“…These bands are similar to those observed in thorneite ($ 700 cm À1 ; , bairdite (721 cm À1 ; Kampf et al, 2013a), eckhardite (729 cm À1 ; Kampf et al, 2013b), and andychristyite (706 cm À1 ; Kampf et al, 2016). Frost & Keeffe (2009) undertook a Raman spectroscopic study of the mineral xocomecatlite [reported as Te VI ]; however, until more is known about the chemistry of xocomecatlite, this study cannot be reliably used for comparison with the Raman spectrum of cesbronite. No evidence for O-H stretches was observed, despite the presence of OH groups confirmed in the crystal structure below.…”

Effect of Al content on the structure of Al‐substituted goethite: a micro‐Raman spectroscopic study

“…The Raman technique is being increasingly employed in our understanding of related minerals and investigating corrosion product films on the metal surface because this technique can provide quick identification of compounds present in surface films as thin as 5 nm, and water or/and hydroxyls give a weak Raman spectra. [24,25,33,[35][36][37][38][39][40][41][42][43][44][45][46][47][48] Thibeau et al [24] investigated the possible corrosion products of iron by using Raman spectroscopy. Faria et al [25,26] tried to differentiate heated goethite and natural goethite by using Raman spectroscopy and obtained the Raman spectra of hematite, magnetite, wustite, maghematite, goethite, and lepidocrocite.…”