Effect of different Ge substitution mechanisms on the crystal structure and electronic properties of sphalerite: A DFT study

Abstract

The scattered metal germanium (Ge) often exists in sphalerite via multiple substitution mechanisms, forming Ge-bearing sphalerite. This paper aims to investigate the effects of four different Ge substitution mechanisms on the crystal structure and electronic properties of sphalerite using density functional theory (DFT), namely: (1) Zn²⁺↔Ge²⁺, (2) 2Zn²⁺↔Ge⁴⁺+vacancy, (3) 3Zn²⁺↔Ge⁴⁺+2Cu⁺, and (4) 3Zn²⁺↔Ge⁴⁺+Fe²⁺+vacancy. The results indicate that the four forms of Ge substitution mechanisms introduce impurity energy levels into the forbidden band interval of sphalerite, leading to a significant decrease in band gap and an enhancement of electrical conductivity. And the impurity energy levels are mainly contributed by atomic orbitals of Ge 4s, Cu 3d, and Fe 3d. The Ge—S bonds in (1)-type Ge-bearing sphalerite exhibit weak covalency, while those in the other three types of Ge-bearing sphalerite show significantly stronger covalency. Frontier orbital analysis suggests that all four forms of Ge substitution mechanisms enhance the interaction between sphalerite and butyl xanthate, with the order of interaction intensity being: (4)-type>(3)-type>(2)-type >(1)-type≈ideal sphalerite.

Keywords

sphalerite / germanium / substitution / density functional theory

References

[1] Cook N J, Ciobanu C L, Pring A, et al. . Trace and minor elements in sphalerite: A LA-ICPMS study [J]. Geochimica et Cosmochimica Acta. 2009, 73(16): 4761-4791

[2] George L L, Cook N J, Ciobanu C L. Partitioning of trace elements in co-crystallized sphalerite-galenachalcopyrite hydrothermal ores [J]. Ore Geology Reviews. 2016, 77: 97-116

[3] Pring A, Wade B, Mcfadden A, et al. . Coupled substitutions of minor and trace elements in co-existing sphalerite and wurtzite [J]. Minerals. 2020, 10(2): 147

[4] Fan M-s, Ni P, Pan J-y, et al. . Rare disperse elements in epithermal deposit: Insights from LA-ICP-MS study of sphalerite at Dalingkou, South China [J]. Journal of Geochemical Exploration. 2023, 244: 107124

[5] Beaucamp C M E, Gammons C H, Thompson J M, et al. . Fluorescent sphalerite rich in tungsten, copper, gallium, silver, and other elements from the Cordilleran-style, polymetallic veins of Philipsburg, Montana [J]. Ore Geology Reviews. 2024, 173: 106267

[6] Müller D, Groves D I, Santosh M. Metallic mineral resources [M]. 2025, Amsterdam, Elsevier

[7] Höll R, Kling M, Schroll E. Metallogenesis of germanium: A review [J]. Ore Geology Reviews. 2007, 30(34): 145-180

[8] Patel M, Karamalidis A K. Germanium: A review of its US demand, uses, resources, chemistry, and separation technologies [J]. Separation and Purification Technology. 2021, 275: 118981

[9] Cook N, Etschmann B, Ciobanu C, et al. . Distribution and substitution mechanism of Ge in a Ge-(Fe)-bearing sphalerite [J]. Minerals. 2015, 5(2): 117-132

[10] Yuan B, Zhang C-q, Yu H-j, et al. . Element enrichment characteristics: Insights from element geochemistry of sphalerite in Daliangzi Pb–Zn deposit, Sichuan, Southwest China [J]. Journal of Geochemical Exploration. 2018, 186: 187-201

[11] Bonnet J, Cauzid J, Testemale D, et al. . Characterization of germanium speciation in sphalerite (ZnS) from central and eastern Tennessee, USA, by X-ray absorption spectroscopy [J]. Minerals. 2017, 7(5): 79

[12] Belissont R, Boiron M C, Luais B, et al. . LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac-Saint-Salvy deposit (France): Insights into incorporation mechanisms and ore deposition processes [J]. Geochimica et Cosmochimica Acta. 2014, 126: 518-540

[13] Belissont R, Muñoz M, Boiron M C, et al. . Distribution and oxidation state of Ge, Cu and Fe in sphalerite by μ-XRF and K-edge μ-XANES: Insights into Ge incorporation, partitioning and isotopic fractionation [J]. Geochimica et Cosmochimica Acta. 2016, 177: 298-314

[14] Johan Z. Indium and germanium in the structure of sphalerite: An example of coupled substitution with Copper [J]. Mineralogy and Petrology. 1988, 39(3): 211-229

[15] Liu W-h, Mei Y, Etschmann B, et al. . Germanium speciation in experimental and natural sphalerite: Implications for critical metal enrichment in hydrothermal Zn-Pb ores [J]. Geochimica et Cosmochimica Acta. 2023, 342: 198-214

[16] Tang X-q, Long Q-r, Chen J-h, et al. . An in-situ study of the interaction mechanism between xanthate and unactivated/Cu-activated sphalerite surfaces at solidliquid interfaces [J]. Applied Surface Science. 2024, 665: 160300

[17] Long X-h, Chen Y, Chen J-h, et al. . The effect of water molecules on the thiol collector interaction on the galena (PbS) and sphalerite (ZnS) surfaces: A DFT study [J]. Applied Surface Science. 2016, 389: 103-111

[18] Feng Q-c, Zhang Y-c, Zhang G, et al. . A novel sulfidization system for enhancing hemimorphite flotation through Cu/Pb binary metal ions [J]. International Journal of Mining Science and Technology. 2024, 34(12): 1741-1752

[19] Yang W-h, Tang Y-y, Huang B, et al. . Experimental and molecular dynamics simulation insights into enhanced flotation of sulfidized smithsonite in a Cu–Pb dual activation system [J]. Green and Smart Mining Engineering. 2025, 2(1): 8-17

[20] Feng Y, Chen Y, Chen J-H. The mechanism of surface activation in sphalerite by metal ions with d10 electronic configurations: Experimental and DFT study [J]. Applied Surface Science. 2024, 649: 159181

[21] Feng Y, Li Z-f, Chen J-h, et al. . Effect of content and spin state of iron on electronic properties and floatability of iron-bearing sphalerite: A DFT+U study [J]. International Journal of Mining Science and Technology. 2023, 33(12): 1563-1571

[22] Yang X, Li Y-q, Chen H-m, et al. . A DFT study on flotation behavior of sphalerite with indium and iron impurities [J]. Minerals Engineering. 2023, 204: 108393

[23] Dong J-s, Liu Q-j, Subhonqulov S H, et al. . Research on the flotation of sphalerite and germanium-bearing sphalerite activated by copper ion and its mechanism difference [J]. Minerals Engineering. 2022, 186: 107756

[24] Sheng J, Liu Q-j, Dong J-s, et al. . Density functional theory study on the effect of germanium doping in sphalerite on the adsorption mechanism of butyl xanthate [J]. Chemical Physics. 2023, 571: 111907

[25] Sheng J, Liu Q-j, Dong J-s, et al. . Mechanism of germanium doping in sphalerite on copper ion activation: A DFT study [J]. Chemical Physics. 2022, 562: 111667

[26] Liu Y-c, Li Y-q, Chen J-h, et al. . Influence of sulfur vacancy on pyrite oxidization by water and oxygen molecules [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2022, 634: 127954

[27] Chen J-h, Wang J-m, Li Y-q, et al. . Effects of surface spatial structures and electronic properties of chalcopyrite and pyrite on Z-200 selectivity [J]. Minerals Engineering. 2021, 163: 106803

[28] Zhang J-j, Li Y-q, Chen J-H. Water-oxygen interaction on marcasite (101) surface: DFT calculation [J]. International Journal of Mining Science and Technology. 2022, 32(1): 191-199

[29] Ke B-l, Chen J-h, Cheng W. Galvanic interaction between different grinding media and galena (100) surface and its influence on galena flotation behavior: A DFT study [J]. Applied Surface Science. 2022, 571: 151379

[30] Liu Y-c, Chen J-h, Li Y-q, et al. . First-principles study on the co-adsorption of water and oxygen molecules on chalcopyrite (112)-M surface [J]. International Journal of Mining Science and Technology. 2023, 33(8): 1055-1063

[31] Wu Z-q, Tang X-q, Feng Y, et al. . Effect of natural non-metallic impurities on the electronic structure and optical properties of sphalerite ZnS [J]. Micro and Nanostructures. 2024, 189: 207818

[32] Yang X, Li Y-q, Chen J-H. DFT study of the occurrence state of in and the correlation of in and Fe in sphalerite [J]. Minerals Engineering. 2022, 183: 107596

[33] Perdew J, Burke K, Ernzerhof M. Generalized gradient approximation made simple [J]. Physical Review Letters. 1996, 77(18): 3865-3868

[34] Monkhorst H J, Pack J D. Special points for Brillouin-zone integrations [J]. Physical Review B. 1976, 13(12): 5188-5192

[35] Skinner B J, Barton P B, et al. . The substitution of oxygen for sulfur in wurtzite and sphalerite [J]. American Mineralogist. 1960, 45: 612-625

[36] Skinner B J. Unit-cell edges of natural and synthetic sphalerites [J]. American Mineralogist. 1961, 46: 1399-1411

[37] Tran T K, Park W, Tong W, et al. . Photoluminescence properties of ZnS epilayers [J]. Journal of Applied Physics. 1997, 81(6): 2803-2809

[38] Chen Y, Chen J-h, Guo J. A DFT study on the effect of lattice impurities on the electronic structures and floatability of sphalerite [J]. Minerals Engineering. 2010, 23(14): 1120-1130

[39] Fujimoto H, Fukui K. Molecular orbital theory of chemical reactions [J]. Advances in Quantum Chemistry. 1972, 6(8): 177-201

[40] Fukui K, Yonezawa T, Shingu H. A molecular orbital theory of reactivity in aromatic hydrocarbons [J]. The Journal of Chemical Physics. 1952, 20(4): 722-725

RIGHTS & PERMISSIONS

Central South University