Abstract
The structural properties of modulated SrGe6−x (x≈0.45) were investigated by means of single-crystal and powder X-ray diffraction combined with quantum chemical calculations. The framework compound SrGe6−x adopts a defect variant of the EuGa2Ge4-type crystal structure. Samples of the binary compound with nominal compositions 0≤x≤0.5 were synthesized at pressures from 5 to 6 GPa and a temperature of typically 1400 K. The product reveals diffraction peaks of the EuGa2Ge4-type subcell plus additional reflections indicating an ordered superstructure. Detailed crystal structure analysis evidences the incommensurate nature of the superstructure and a modulation of the vacancy ordering in the germanium network. The computations have shown that the non-stoichiometric composition of the framework with its local defect organization affects the calculated charge of the strontium anions. Although the chemical composition is close to a charge-balanced situation, temperature-dependent resistivity measurements showed metal-type conductivity. At ambient pressure SrGe6−x decomposes exothermally and irreversibly at T=680(10) K into SrGe2 and germanium, indicating its metastable nature at ambient pressure.
Dedicated to: Professor Wolfgang Bensch on the occasion of his 65th birthday.
Acknowledgements
We thank Susann Leipe for high-pressure syntheses, Marcus Schmidt and Susann Scharsach for DTA characterizations as well as Ulrich Burkhardt, Monika Eckert and Sylvia Kostmann for metallographic investigations. Valuable discussions with Frank Wagner and Miroslav Kohout are gratefully acknowledged.
References
[1] A. Wosylus, Yu. Prots, U. Burkhardt, W. Schnelle, U. Schwarz, Sci. Technol. Adv. Mater.2007, 8, 383.10.1016/j.stam.2007.06.005Search in Google Scholar
[2] A. Wosylus, Yu. Prots, U. Burkhardt, W. Schnelle, U. Schwarz, Yu. Grin, Z. Naturforsch. 2006, 61b, 1485.10.1515/znb-2006-1204Search in Google Scholar
[3] A. Wosylus, Yu. Prots, U. Burkhardt, W. Schnelle, U. Schwarz, Yu. Grin, Solid State Sci. 2006, 8, 773.10.1016/j.solidstatesciences.2006.04.003Search in Google Scholar
[4] B. Eisenmann, H. Schäfer, R. Zahler, J. Less-Common Met. 1986, 118, 43.10.1016/0022-5088(86)90609-0Search in Google Scholar
[5] H. Fukuoka, S. Yamanaka, E. Matsuoka, T. Takabatake, Inorg. Chem. 2005, 44, 1460.10.1021/ic0485615Search in Google Scholar
[6] W. Carrillo-Cabrera, S. Budnyk, Yu. Prots, Yu. Grin, Z. Anorg. Allg. Chem. 2004, 630, 2267.10.1002/zaac.200400268Search in Google Scholar
[7] A. Kaltzoglou, T. F. Fässler, M. Christensen, S. Johnsen, B. B. Iversen, I. A. Presniakov, A. N. Sobolev, A. V. Shevel’kov, J. Mater. Chem. 2008, 18, 5630.10.1039/b810783aSearch in Google Scholar
[8] T. Leisegang, D. C. Meyer, T. Doert, G. Zahn, T. Weißbach, D. Souptel, G. Behr, P. Paufler, Z. Kristallogr. 2005, 220, 128.10.1524/zkri.220.2.128.59116Search in Google Scholar
[9] J. D. Bryan, G. D. Stucky, Chem. Mater. 2001, 13, 253.10.1021/cm000233pSearch in Google Scholar
[10] W. Carrillo-Cabrera, S. Paschen, Yu. Grin, J. Alloys Compd. 2002, 333, 4.10.1016/S0925-8388(01)01725-XSearch in Google Scholar
[11] D. Walker, M. A. Carpenter, C. M. Hitch, Am. Mineral. 1990, 75, 1020.Search in Google Scholar
[12] D. A. Young, Phase Diagrams of the Elements, UC Press, Oxford, 1991, p. 122 and references therein.10.1525/9780520911482Search in Google Scholar
[13] V. Petříček, M. Dušek, L. Palatinus, Z. Kristallogr. 2014, 229, 345.10.1515/zkri-2014-1737Search in Google Scholar
[14] L. Akselrud, Yu. Grin, J. Appl. Cystallogr. 2014, 47, 803.10.1107/S1600576714001058Search in Google Scholar
[15] O. Jepsen, A. Burkhardt, O. K. Andersen, TB-LMTO-ASA (version 4.7), Max-Planck-Institut für Festkörperforschung, Stuttgart (Germany) 1999.Search in Google Scholar
[16] U. von Barth, L. Hedin, J. Phys. C1972, 5, 1629.10.1088/0022-3719/5/13/012Search in Google Scholar
[17] O. K. Andersen, Phys. Rev. B1975, 12, 3060.10.1103/PhysRevB.12.3060Search in Google Scholar
[18] M. Kohout, Faraday Discuss. 2007, 135, 43.10.1039/B605951CSearch in Google Scholar
[19] F. R. Wagner, V. Bezugly, M. Kohout, Yu. Grin, Chem. Eur. J. 2007, 13, 5724.10.1002/chem.200700013Search in Google Scholar
[20] M. Kohout, DGrid (version 5.0), Radebeul (Germany) 2018.Search in Google Scholar
[21] R. F. W. Bader, Atoms in Molecules: a Quantum Theory. Oxford University Press, Oxford, 1999.Search in Google Scholar
[22] M. Kohout, A. Savin, Int. J. Quantum Chem. 1996, 60, 875.10.1002/(SICI)1097-461X(1996)60:4<875::AID-QUA10>3.0.CO;2-4Search in Google Scholar
[23] Yu. Grin in Comprehensive Inorganic Chemistry II, Vol 2, (Eds.: J. Reedijk, K. R. Poeppelmeier), Elsevier, Oxford, 2013, p. 359.10.1016/B978-0-08-097774-4.00215-1Search in Google Scholar
[24] D. Bende, F. R. Wagner, Yu. Grin, Inorg. Chem. 2015, 54, 3970.10.1021/acs.inorgchem.5b00135Search in Google Scholar
[25] L. Akselrud, A. Wosylus, R. Castillo, U. Aydemir, Yu. Prots, W. Schnelle, Yu. Grin, U. Schwarz, Inorg. Chem. 2014, 53, 12699.10.1021/ic5021065Search in Google Scholar PubMed
[26] T. Janssen, A. Janner, A. Looijenga-Vos, P. M. de Wolff, Incommensurate and Commensurate Modulated Structures in International Tables for Crystallography, Volume C, 3rd edition (Ed.: E. Prince), Kluwer Academic Publisher, Dordrecht, 2004, chapter 9.8, p. 907.10.1107/97809553602060000624Search in Google Scholar
[27] V. Petrícek, A. van der Lee, M. Evain, Acta Crystallogr.1995, A51, 529.10.1107/S0108767395000365Search in Google Scholar
[28] M. Baitinger, B. Böhme, A. Ormeci, Yu. Grin in The Physics and Chemistry of Inorganic Clathrates, (Ed.: G. S. Nolas), Springer, Dordrecht, 2014, p. 35.10.1007/978-94-017-9127-4_2Search in Google Scholar
[29] A. Bhattacharya, C. Carbogno, B. Böhme, M. Baitinger, Yu. Grin, M. Scheffler, Phys. Rev. Lett. 2017, 118, 236401.10.1103/PhysRevLett.118.236401Search in Google Scholar PubMed
[30] R. Castillo, W. Schnelle, A. I. Baranov, U. Burkhardt, M. Bobnar, R. Cardoso-Gil, U. Schwarz, Yu. Grin, Z. Naturforsch. 2016, 71b, 585.10.1515/znb-2016-0047Search in Google Scholar
[31] X.-J. Feng, Y. Prots, M. Bobnar, M. P. Schmidt, W. Schnelle, J.-T. Zhao, Yu. Grin, Chem. Eur. J. 2015, 21, 14471.10.1002/chem.201501236Search in Google Scholar PubMed
[32] A. Palasyuk, Yu. Grin, G. J. Miller, J. Am. Chem. Soc. 2014, 136, 3108.10.1021/ja411150eSearch in Google Scholar PubMed
[33] L. T. K. Nguyen, U. Aydemir, M. Baitinger, E. Bauer, H. Borrmann, U. Burkhardt, J. Custers, A. Haghighirad, R. Höfler, K. D. Luther, F. Ritter, W. Assmus, Yu. Grin, S. Paschen, Dalton Trans. 2010, 39, 1071.10.1039/B919791PSearch in Google Scholar PubMed
[34] A. Ormeci, Yu. Grin, J. Thermoelectr. 2015, 6, 16.Search in Google Scholar
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