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Discovery of chalcogenides structures and compositions using mixed fluxes


Advancements in many modern technologies rely on the continuous need for materials discovery. However, the design of synthesis routes leading to new and targeted solid-state materials requires understanding of reactivity patterns1,2,3. Advances in synthesis science are necessary to increase efficiency and accelerate materials discovery4,5,6,7,8,9,10. We present a highly effective methodology for the rational discovery of materials using high-temperature solutions or fluxes having tunable solubility. This methodology facilitates product selection by projecting the free-energy landscape into real synthetic variables: temperature and flux ratio. We demonstrate the effectiveness of this technique by synthesizing compounds in the chalcogenide system of A(Ba)-Cu-Q(O) (Q = S or Se; A = Na, K or Rb) using mixed AOH/AX (A = Li, Na, K or Rb; X = Cl or I) fluxes. We present 30 unreported compounds or compositions, including more than ten unique structural types, by systematically varying the temperature and flux ratios without requiring changing the proportions of starting materials. Also, we found that the structural dimensionality of the compounds decreases with increasing reactant solubility and temperature. This methodology serves as an effective general strategy for the rational discovery of inorganic solids.

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Fig. 1: Compositional and dimensionality control with basicity.
Fig. 2: Perturbation of reaction pathways when BaO is present.
Fig. 3: Projecting the energy landscape onto synthetic parameters.

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Data availability

Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, with deposition numbers 2184424–2184451, corresponding to compounds shown in Table 1: I (Na4+xOCu4Se4, CSD 2184424), II (Na10+xO2Cu11+xSe10, CSD 2184425), III (Na5+xOCu8Se6, CSD 2184427), IV (Na4+xOCu4S4, CSD 2184435), V (Na10+xO2Cu11+xS10, CSD 2184429), VI (Na5+xOCu8S6, CSD 2184433), VIII (K4+xOCu4Se4, CSD 2184438), IX (NaCu3S2, CSD 2184426), X (NaCu3Se2, CSD 2184428), XII (Na(Cu0.6Li0.4)S, CSD 2184430), XIII (Na(Cu0.6Li0.4)Se, CSD 2184431), XIV (BaCu1.4Li0.6S2, CSD 2184436), XV ((Ba0.44Rb0.56)Cu2Se2, CSD 2184441), XVI (Na3BaCu7S6, CSD 2184432), XVII (K3BaCu7S6, CSD 2184434), XVIII (Ba2Cu2Na1.3O1.1S3, CSD 2184442), XIX (Ba4.5Cu6.7Na1.7O4S6, CSD 2184439), XX (Ba2−xCu5.5OSe4, CSD 2184437), XXI (Ba2Cu0.8O2Cu2Se2, CSD 2184443), XXII (Ba2Na0.55O2Cu2Se2, CSD 2184440), XXIII ((Ba1.63K0.37)O2Cu2Se2, CSD 2184445), XXIV (Ba2Cu0.8O3CuS, CSD 2184450), XXV (KCu5Se3, CSD 2184444), XXVI (RbCu7−xSe4, CSD 2184448), XXVII (Ba4Rb6Cu12Se13, CSD 2184447), XXVIII (Na3Cu4Se4, CSD 2184446), XXIX (BaK2Cu4S4−xSex, CSD 2184451), XXX (BaK2Cu8S6, CSD 2184449). Copies of the data can be obtained free of charge at Source data for Extended Data Fig. 3 is provided within this paper. Data are also available on request. Source data are provided with this paper.


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This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Work carried out at the Center for Nanoscale Materials (SEM, ACAT and Carbon high-performance computing cluster), a US Department of Energy (DOE) Office of Science User Facility, was supported by the US DOE Office of Basic Energy Sciences under contract no. DE-AC02-06CH11357. The computational work is supported by the US DOE Office of Science Scientific User Facilities AI/ML project titled 'A digital twin for spatiotemporally resolved experiments.' M.K.Y.C. acknowledges support from the BES SUFD Early Career award. Work at the beamlines 15-IDD and 17-BM at the Advanced Photon Source (APS) at Argonne National Laboratory was supported by the US DOE, Office of Science, Office of Basic Energy Sciences under contract no. DE-AC02-06CH11357. NSF’s ChemMatCARS Sector 15 is supported by the Divisions of Chemistry (CHE) and Materials Research (DMR), National Science Foundation, under grant no. NSF/CHE-1834750.

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Authors and Affiliations



The work was conceived by X.Z., D.-Y.C. and M.G.K., with input from all authors. X.Z. carried out the synthesis, lab X-ray diffraction and elemental analysis. X.Z. and W.X. collected and analysed in situ synchrotron diffraction data. V.-S.-C.K., L.W. and M.K.Y.C. performed first-principle calculations. X.Z., T.C. and Y.-S.C. collected and analysed single-crystal diffraction data. L.Y. and J.W. collected and analysed electron energy loss spectroscopy spectra. D.-Y.C. and M.G.K. supervised the project.

Corresponding author

Correspondence to Mercouri G. Kanatzidis.

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Nature thanks Hans Conrad zur Loye and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Reaction pathways in the (K, Li)OH/KI flux.

a, XXV (KCu5Se3). b, α-KCu3Se2. c, K3Cu8Se6. d, KCu2Se2. e, K4+xOCu4Q4. f, XI (KCu3S2). g, α-KCu3S2. Compounds from Table 1 are shown as VII (K4+xOCu4S4), VIII (K4+xOCu4Se4), XI (KCu3S2) and XXV (KCu5Se3). The crystal structures VII and VIII are identical to that of I (Na4+xOCu4Se4) and XI is isostructural with IX (KCu3S2). Purple, blue, red, light yellow and light green spheres represent K, Cu, O, S and Se atoms, respectively.

Extended Data Fig. 2 Reaction pathways in the (Rb, Li)OH/RbI flux.

a, RbCu4Se3. b, XXVI (RbCu7−xSe4). c, Rb3Cu8Se6. Compounds from Table 1 are shown as XXVI (RbCu7−xSe4). Pink, blue and light green spheres represent Rb, Cu and Se atoms, respectively.

Extended Data Fig. 3 Panoramic synthesis.

In situ synchrotron powder X-ray diffraction patterns of reactions collected in the mixed flux of NaOH/NaI for [OH] = 0.60, Q = Se (a), [OH] = 0.80, Q = Se (b), [OH] = 0.80, Q = Se, Na/Li = 1 (c) and [OH] = 0.65, Q = S with addition of BaO (d). Their respective temperature profiles are shown in Fig. S3. G marked with the purple box in d is probably several different unknown phases with overlapping Bragg peaks.

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Supplementary Information

This file contains further experimental details and Supplementary Figures 1–13.

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Zhou, X., Kolluru, V.S.C., Xu, W. et al. Discovery of chalcogenides structures and compositions using mixed fluxes. Nature 612, 72–77 (2022).

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