Vibrational Spectroscopic Study of the Uranyl Selenite Mineral Derriksite
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 473–477 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa Vibrational spectroscopic study of the uranyl selenite mineral derriksite Cu4UO2(SeO3)2(OH)6ÁH2O ⇑ Ray L. Frost a, , JirˇíCˇejka b, Ricardo Scholz c, Andrés López a, Frederick L. Theiss a, Yunfei Xi a a School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia b National Museum, Václavské námeˇstí 68, CZ-115 79 Praha 1, Czech Republic c Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35400-00, Brazil highlights graphical abstract We have studied the mineral derriksite Cu4UO2(SeO3)2(OH)6ÁH2O. A comparison was made with the other uranyl selenites. Namely demesmaekerite, marthozite, larisaite, haynesite and piretite. Approximate U–O bond lengths in uranyl and O–HÁÁÁO hydrogen bond lengths were calculated. article info abstract Article history: Raman spectrum of the mineral derriksite Cu4UO2(SeO3)2(OH)6ÁH2O was studied and complemented by Received 20 May 2013 the infrared spectrum of this mineral. Both spectra were interpreted and partly compared with the spec- Received in revised form 29 July 2013 tra of demesmaekerite, marthozite, larisaite, haynesite and piretite. Observed Raman and infrared bands Accepted 2 August 2013 were attributed to the (UO )2+, (SeO )2À, (OH)À and H O vibrations. The presence of symmetrically dis- Available online 22 August 2013 2 3 2 tinct hydrogen bonded molecule of water of crystallization and hydrogen bonded symmetrically distinct hydroxyl ions was inferred from the spectra in the derriksite unit cell. Approximate U–O bond lengths in Keywords: uranyl and O–HÁÁÁO hydrogen bond lengths were calculated from the Raman and infrared spectra of Derriksite derriksite. Selenite Raman spectroscopy Ó 2013 Elsevier B.V. All rights reserved. Infrared spectroscopy Uranyl U–O bond lengths Introduction Uranyl anion topology of uranyl natural and synthetic com- pounds inclusive of uranyl selenites has been elaborated by Burns The crystal chemistry of selenium(IV) oxo-compounds shows [3–6]. According to Finch and Murakami [7], uranyl selenites occur great structural versatility expressed by the great number of differ- where Se-bearing sulfide minerals are undergoing oxidation and ent compounds [1]. Crystallochemical systematics of selenites was dissolution. Derriksite, demesmaekerite, guilleminite and mar- presented by Serezhkina et al. [2]. thozite are from the Musonoi Cu–Co mine, near Kalwezi, Katanga Province, Democratic Republic of Congo, piretite and also guillem- inite from Shinkolobwe, Katanga Province, Democratic Republic of ⇑ Corresponding author. Tel.: +61 7 3138 2407; fax: +61 7 3138 1804. Congo, haynesite and larisaite from the Repete mine, San Juan Co., E-mail address: [email protected] (R.L. Frost). Utah, U.S.A [8,9]. 1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.saa.2013.08.026 474 R.L. Frost et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 473–477 Structures of derriksite, Cu4UO2(SeO3)2(OH)6ÁH2O [10,11], and monochromator, a filter system and a CCD detector (1024 pixels). demesmaekerite, Pb2Cu5[(UO2)(SeO3)3]2(OH)6Á(H2O)2, are charac- The Raman spectra were excited by a Spectra-Physics model 127 terized by infinite chains formed from uranyl and selenite ions He–Ne laser producing highly polarized light at 633 nm and col- [6,12], while those of the remaining uranyl selenite minerals, guil- lected at a nominal resolution of 2 cmÀ1 and a precision of À1 À1 leminite, Ba[(UO2)3O2(SeO3)2]Á(H2O)3 [13], marthozite, Cu[(UO2)3- ±1 cm in the range between 200 and 4000 cm . Repeated acqui- O2(SeO3)2](H2O)8 [14], larisaite, Na(H3O)[(UO2)3(SeO3)2O2](H2O)4 sitions on the crystals using the highest magnification (50Â) were [9] and probably also haynesite, [(UO2)3(SeO3)2(OH)2]Á(H2O)5 accumulated to improve the signal to noise ratio of the spectra. Ra- À1 [15,16] and piretite, Ca[(UO2)3(SeO3)2(OH)4]Á(H2O)4 [16] by uranyl man Spectra were calibrated using the 520.5 cm line of a silicon oxo-hydroxo selenite sheets and phosphuranylite anion sheet wafer. The Raman spectrum of at least 10 crystals was collected to topology. According to Chukanov et al. [9], the general formula of ensure the consistency of the spectra. the minerals guilleminite, marthozite, haynesite, piretite and lar- isaite is M [(UO ) (SeO ) (O,OH) ]ÁnH O, where a = 3–8, 0–1 2 3 3 2 2–4 2 Infrared spectroscopy M=M2+,2M+. In derriksite, the uranyl coordination polyhedra are formed from tetragonal (square) dipyramids UO O , in dem- 2 4 Infrared spectra were obtained using a Nicolet Nexus 870 FTIR esmaekerite pentagonal dipyramids UO O , and probably in all 2 5 spectrometer with a smart endurance single bounce diamond remaining natural uranyl selenites from pentagonal and hexagonal ATR cell. Spectra over the 4000–525 cmÀ1 range were obtained dipyramids UO O and UO O , respectively similarly as in phos- 2 5 2 6 by the co-addition of 128 scans with a resolution of 4 cmÀ1 and a phuranylite. According to Ginderow and Cesbron [11], derriksite mirror velocity of 0.6329 cm/s. Spectra were co-added to improve contains the brucite-type layers of CuO . Derriksite is structurally 6 the signal to noise ratio. The infrared spectra are given in the sup- related to deloryite, Cu (UO )(MoO ) (OH) and the difference in 4 2 4 2 6 plementary information. space group between the two minerals is the direct consequence Spectral manipulation such as baseline correction/adjustment of the replacement of the SeO trigonal pyramids in derriksite by 3 and smoothing were performed using the Spectracalc software the MoO tetrahedra in deloryite. Deloryite does not contain any 4 package GRAMS (Galactic Industries Corporation, NH, USA). Band molecular water. This differs from derriksite containing one water component analysis was undertaken using the Jandel ‘Peakfit’ soft- molecule. Ginderow and Cesbron [11] inferred from thermogravi- ware package that enabled the type of fitting function to be se- metric curve (TGA) presented by Cesbron et al. [10], that the first lected and allows specific parameters to be fixed or varied dehydration step (up to approximately 300 °C) may be connected accordingly. Band fitting was done using a Lorentzian–Gaussian with adsorbed water. However, the original Cesbron’s interpreta- cross-product function with the minimum number of component tion that this first TGA step corresponds with one molecule of bands used for the fitting process. The Gaussian–Lorentzian ratio water of crystallization [10] seems to be more correct. was maintained at values greater than 0.7 and fitting was under- Raman spectroscopy was proven most useful for the character- taken until reproducible results were obtained with squared corre- ization of secondary uranyl containing minerals [17–23]. The aim lations of r2 greater than 0.995. of this research is the study of Raman spectra of the natural uranyl selenite derriksite, complemented by its infrared spectra. The pa- per is a part of systematic vibrational spectroscopic research of sec- Results and discussion ondary minerals formed in the oxidation zone, inclusive uranyl minerals originating during hydration–oxidation weathering of The Raman spectrum of derriksite over the full wavenumber primary uranium minerals, such as uraninite. Raman spectroscopy range is illustrated in Fig. 1a. This figure displays the position was proven most useful for the characterization of secondary ura- and relative intensities of the Raman bands of derriksite. It may nyl containing minerals. In order to identify and characterize the be observed that there are large parts of the spectrum where no Raman and infrared spectra of derriksite, this research reports intensity is found; therefore the spectrum is subdivided into sec- the Raman and infrared spectrum of derriksite and relates the tions based upon the type of vibration being studied. The infrared spectra of derriksite to the structure of the mineral. spectrum of derriksite over the full wavenumber range is illus- trated in Fig. 1b. This spectrum shows the position and relative intensities of the infrared bands of derriksite. The Raman spectrum Experimental of derriksite over the 700 to 1400 cmÀ1 spectral range is reported in Fig. 2a. The infrared spectrum of derriksite over the 600 to Mineral 1400 cmÀ1 spectral range is reported in Fig. 2b. The Raman spectra of derriksite over the 300 to 700 cmÀ1 and 100 to 300 cmÀ1 spec- For the development of this work, one single crystal of derrik- tral ranges are reported in Fig. 3. The Raman and infrared spectra site was chosen for our investigation. Sample was obtained from of the OH stretching region (2600–4000 cmÀ1) are shown in the collection of the Geology Department of the Federal University Fig. 4. The Raman and infrared spectra in the water bending region of Ouro Preto, Minas Gerais with sample code SAB-098. The crystal (1300–1800 cmÀ1) are given in Fig. 5. is deep green and transparent, with up to 2.0 mm in length and oc- 2+ The free linear uranyl group (UO2) , symmetry D h, has four curs in association with malachite. The studied sample is from 1 normal vibrations, but only three fundamentals: the m1 symmetric Musonoi Mine, Katanga, Democratic Republic of Congo and can stretching vibration, Raman active (approximately 900–700 cmÀ1), be considered a type material. the m2 (d) doubly degenerate bending vibration, infrared active The chemical analyses of the mineral have been made.