• • • THE BINDING STATE OF INDIUM IN NATURAL CHALCOGENIDES: IN A XANES APPROACH THROUGH THE L 3 ABSORPTION EDGE * Laboratório Nacional de Energia e Geologia Cancún, Mexico Ma Ondina FIGUEIREDO & Teresa PEREIRA da SILVA August 16-20, 2009 CENIMAT/I3N, Mat. Sci. Dpt., Fac. Sci. Techn., New Univ. Lisbon, A Brief Summary of Indium Crystal Chemistry Symposium 20 2829-516 Caparica, and LNEG, Geol. Data Centre, Apt. 7586, Assigned as a native metal associated with lead in Transbaikalia [4], indium 2721-866 Alfragide, Portugal (Z=49) has the electronic structure [Kr] 4d10 5s2 5p1, and frequently assumes the Poster nr. 1 trivalent state, thus suggesting the inertness of 5s2 electron-pair. Like gallium Introduction MAIN CRYSTAL STRUCTURE-TYPES (STP) of NATURAL and unlike tin - other important “High-Tech” elements -, indium seldom forms Indium became one of the most relevant scarce CHALCOGENIDES (Minerals) specific minerals, occurring dispersed within polymetallic sulfide ores (Table 1). Octahedral Sulfides metals used in the last decades to produce new The sulphide roquesite (CuInS2) was the first In-mineral to be described [5], Disulfides |S=S| dimers SULPHO- “high-tech devices” based on innovative nano- followed [6] by indite (Fe In2 S4) and dzhalindite, a tri-hydroxide with In (OH)6 o t <c> SALTS : LCD Fe [| S2 |] octahedra. The recovery of indium stands mostly on the processing of zinc technologies - liquid crystal displays ( s), Polysomatic S organic light emitting diodes (OLEDs) and the series blende or sphalerite - the cubic zinc sulphide that typifies tetrahedral sulphides recently introduced transparent flexible thin-films made-up (fig.2), where cations fill half of the available tetrahedral sites in a cubic closest Pb from slabs packing (ccp) of sulfur anions (S=); the crystal-chemical formula is Znt[St]c, (TFTs) [1], manufactured with ionic amorphous extracted from galena o o c where t stands for tetrahedral coordination and c quotes the anion packing [7]. In oxide semi-conductors (IAOs) within the systems GALENA Pb [S ] structure In-Sn-O (ITO) and In-Ga-Zn-O (IGZO). Since the Nature, In is mainly carried in solid solution or diadochic replacement by S= anions sphalerite and also by excess-metal copper-rich “tetrahedral sulphides”, like early 1970s, ternary semi-conducting compounds Tetrahedral Sulfides t t t c t t t t c of chalcopyrite-type turned also into promising PYRITE bornite, Cu5 Fe [S4 ] and sakuraite, (Cu,Ag)2 (Zn,Fe) (In,Sn) [S4 ] , plus by complex materials for photovoltaic solar cells with increased BLENDE sulfides of the series tetrahedrite-tennantite derived from a ccp array by WURTZITE Fig. 2 or replacing a tetrahedral cluster of anion vacancies for one single S= anion (fig.3). efficiency - e.g., Cu(In,Ga)Se2 (CIGS). (hexagonal closest- Superstructures: packing of anions) SPHALERITE 1) lacunar closest-packings The structural characterization [8,9] of synthetic In-chalcogenides (In6Se7, Indium is a typical chalcophile element seldom t t h t t c 2) insertion of extra cations Zn [S ] Zn [S ] forming specific minerals and occurring dispersed In4Se3, In4Te3, InTe, In7Te10) revealed the occurrence of polymetallic cations, 4+ 5+ within polymetallic natural sulphides, particularly Crystal chemical formulae according to namely, [In2] dimmers and [In3] trimers (fig.4). J. Lima-de-Faria & M.O. Figueiredo (1976) tetrahedral sulphides with excess metal [2]. The J. Solid St. Chem. 16 7-12. average content of indium in the Earth's crust is TETRAHEDRITE –TENNANTITE STP 4+ 5+ o Fig. 4 − [In 2] & [In 3] very low but its consumption is expected to Iberian Pyrite Belt S (tetrahedral increase in the next years, thus focusing a special coordination) π Polycations [8] S (octahedral interest on improving recovery and recycling coordination) In6Se7 technologies and finding new exploitation sites Cu; Zn, Fe, Hg, from promising polymetallic sulfide ores - e.g., the Cd, Pb tr Cu, Ag t Iberian Pyrite Belt [3] (fig.1). Understanding indium t Sb; As crystal chemistry has become a demanding task and Where is In? this work is a contribution to interpret its binding Fig. 3 WhereWhere is Inislocated?In? 1+ t,tr 2+ t 3+ π t o <c > In4Se3 state in natural chalcogenides using synchrotron Fig. 1 Crystal chemical formula (M ) 10 (M ) 2 (M ) 4 [ S 12 S ] Dimers Trimers radiation X-ray absorption spectroscopy. ESRF (a) Table 1 − CHEMISTRY of CHALCOGENIDE MINERALS Grenoble/France (b) In (metal) (MORPHOTROPIC DOMAINS, that is, chemical range for diadochic substitutions in minerals deduced from stable synthetic compounds) 3 732.1 3 730.6 In Br Periodic classification 3 726.5 of the Elements In O 3 757.8 2 3 S Fig. 5 3 742.8 3 760.5 In F3 3 745.5 [Periodic Table from K. KRAUSKOPF (1967) Introduction to Geochemistry] Pyrite Tetrahedral structures Galena-plus-sulphosalts / Anions (blende, wurtzite & allied) Fig. 6 − In L3-edge XANES spectra: 3 732.1 E (eV) ID 21 (a) model compounds; (b) points in Experimental beamline chalcogenide sample LS5-180.6 [11] The X-ray absorption spectroscopy experiment at In L3-edge was carried out using the instrumental set-up of ID-21 beamline [10] Results In L3-edge XANES spectra Fig. 7 (fig. 5) at the ESRF (European Synchrotron Radiation Facility). From [13] X-ray absorption spectra reflect the local symmetry Fe S2 A polymetallic chalcogenide ore (In ~ 90ppm) from Lagoa Salgada and chemical bonding of the absorbing element and the ZnS [11] was irradiated, along with metallic indium and model compounds band character of the compound through the position of displaying distinct bonding situations of indium to other ligands the edge jump and the details that follow; the presence of a S2 (oxygen and halides). XANES spectra were collected in fluorescence “white line” indicates unoccupied electronic states [12]. Fe yield mode using a photodiode detector mounted in the horizontal Beyond a white line at 3732.1eV (fig.6a), also displayed plane perpendicular to the X-ray beam, irradiating directly the rough by InF3 XANES spectrum (fig.6b), the spectra collected from sample fragments with a beam-size of 1x0.3μm2. A fixed-exit Si(111) E (eV) the chalcogenide ore show an extra white-line at 3726.5eV PbS monochromator was used for the energy scans, assuring an energy plus details also observed in the spectra of the metal and 0.4 eV resolution of at the In L3-edge. model compounds In2O3 & InF3. Although the In L3-edge 100 μm Fig. 10 – Crystal structure of trigonal spectra from the oxide (fig.7) was already studied in the Fig. 8 – Photomicrograph of a References In F3 [17], with ideal crystal context of ITO thin-films [13] and the spectra from the o h polished section of ore sample [1] E. FORTUNATO, et al. (2005) Adv. Materials 17, 590-594. chemical formula In [F3] metal was discussed a few years ago [14], further study is In LS5-180.6. A fissure is shown in [2] M.O. FIGUEIREDO et al. (2007) Procd. 9th Biennial SGA Mtg., In3+ cations fill only 1/3 of clearly required to fully interpret the spectra collected from Dublin/Ireland, edt. C. Andrew et al., 1355-1357 (ISBN 0-950989-4-4). black. Grains: dark grey, pyrite the available octahedral sites. natural chalcogenides (fig.6a) which are quite distinct from (FeS ); (ZnS); [3] O.C. GASPAR (1984) Mem.& Notícias, Museu Lab. Miner. Geol., F 2 light grey, sphalerite Univ. Coimbra, 98, 137-150. (in Portuguese). the XANES spectra of synthetic spinel-type In2S3 [15]. white, galena (PbS). [4] V.V.IVANOV (1964) Cf. Handbook of Geochem. (1974) Springer- Verlag, vol. II-4, p. 49-A. c Fig. 9 - Condensed-model standard sheet [16] for [5] P. PICOT & R. PIERROT (1963) Bull. Soc. Fr. Min. Crist. 86, 7-11. t o c/h Final Comments [6] A.D. GENKIN & I.V. MURAVEVA (1963) Cf. Amer. Min. 49, 493. A 2 D [X] = [7] M.O. FIGUEIREDO & M.J. BASTO (1986) Garcia de Orta, ser. Geol., Large circles, closest The closest packing array built up by S anions in most Lisboa / IICT 9, 41-53 (in Portuguese). packing atoms (X); A, chalcogenide minerals present in ore sample LS5-180.6 (fig.8) − [8] H. SCHWARTZ, et al. (1995) Zeit. für Kristallogr. 210, 342-347. tetrahedral (t), and D, chalcopyrite, sphalerite, tetrahedrite-tennantite, galena − is very [9] M. EPPLE, et al. (2000) Zeit. für Kristallogr. 215, 445-453. o octahedral sites (o). th suitable to lodge polymetallic cations by filling closely located [10] J. SUSINI et al. (2000) Proc. 6 Internat. Conf. X-Ray Microscopy, X A t Amer. Inst. Phys. 507, 19-28. Ideal radii: rA=0.225 rX interstitial sites, as illustrated by the condensed model sheet of th [11] D. OLIVEIRA et al. (2009) 10 Biennial SGA Mtg., Australia, August. D rD = 0.414 rX a single anionic layer figuring out the interstices available [12] M. BROWN et al. (1977) Phys. Rev. B 15, 738-744. [t-o] & [t-t] distances between successive layers (fig.9). Considering that InF3 is also [13] V. SUBRAMANIAN, et al. (2004) Solid State Ionics 175, 181-184. are assigned in color. a closest-packed compound, despite hexagonal (fig.10), it is not [14] T.K. SHAM (1985) Phys. Rev. B 31, 1888-1902. to exclude that interactions may occur between neighbor In [15] M. WOMES et al. (2004) Solid State Comm. 131, 257-260. * Work developed within the research project PTDC / CTE-GIN / 67027 / 2006 financed [16] J. LIMA-de-FARIA (1965) Zeit. für Kristallogr. 122, 346-358. cations, thus accounting for singularities of the observed white by the Portuguese Foundation for Science & Technology (FCT/MCTES). The financial [17] R.