Pfitzner, Arno

Pompe, Constantin

Na3SbSe3 was obtained by solid state reaction of anhydrous Na2Se, antimony, and selenium in a ratio of 3:2:3. It is air and moisture sensitive and melts at 870 K. Yellow single crystals of Na3SbSe3 were used for single-crystal X-ray diffraction. It crystallizes in the cubic space group P213 (No. 198) with a = 9.0227(2) angstrom, V = 734.53(3) angstrom 3, and Z = 4. Na3SbS3 is isotypic with Na3AsS3. Trigonal SbSe3 pyramids therein act as mono-, bi-, and tridentate ligands to sodium. Sodium is located at three different sites, which are all coordinated by six selenium atoms, providing a strongly distorted octahedral environment. NaSe6 octahedra of identical type share common vertices; in case of different sites also face sharing is observed. Na3SbSe3 shows temperature dependent Na+ conductivity above 380 K, which increases to 2.9? x?106 O1 cm1 at 590 K

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ARTICLEDOI: 10.1002/zaac.201200370Na3SbSe3: Synthesis, Crystal Structure Determination, Raman Spectroscopy,and Ionic ConductivityConstantin Pompe[a] and Arno Pfitzner*[a]Dedicated to Professor Rudolf Hoppe on the Occasion of His 90th BirthdayKeywords: Chalcogenometalates; Sodium; Ion conductor; Crystal structureAbstract. Na3SbSe3 was obtained by solid state reaction of anhydrousNa2Se, antimony, and selenium in a ratio of 3:2:3. It is air and moisturesensitive and melts at 870 K. Yellow single crystals of Na3SbSe3 wereused for single-crystal X-ray diffraction. It crystallizes in the cubicspace group P213 (No. 198) with a = 9.0227(2) Å, V = 734.53(3) Å3,and Z = 4. Na3SbS3 is isotypic with Na3AsS3. Trigonal SbSe3 pyramidstherein act as mono-, bi-, and tridentate ligands to sodium. Sodium isIntroductionAlkali metal containing antimony chalcogenides of the ge-neral composition M3SbQ3 (M = Li, Na, K, Rb, Cs andQ = S, Se, Te) are well characterized. 35 years ago, Sommerand Hoppe already described the isotypic thioantimonates(III)Na3SbS3, K3SbS3, and the thioarsenates(III) Na3AsS3, andK3AsS3, respectively.[1] However, they determined only thecrystal structure of Na3AsS3 and derived the isotypism fromX-ray powder data. It should later become apparent, that al-most every other known compound M3SbQ3 crystallizes in thecubic structure type of Na3AsS3,[2] which was also termed asa “stuffed variety of the NaClO3-type”.[1] They also discussedthe structural relation of M3SbQ3 and the Li3Bi structure type.Later on this structure type was described as derivative of theTh3P4 structure type.[3] Therein, also a group-subgroup schemeis discussed in order to describe the symmetry relations. Con-cerning the crystal structures of the alkali metal chalcogenoan-timonates(III) Li3SbS3 is a solitary exception. It crystallizesorthorhombic in the space group Pna21.[4] The thioantimo-nates(III) M3SbS3 of the heavier alkali-metals rubidium andcesium are not known to date. The same situation is found forthe corresponding antimony tellurides M3SbTe3. Na3SbTe3[5]and K3SbTe3[6] are isotypic to Na3AsS3, whereas similar com-pounds with lithium, rubidium, or cesium are not yet known.The selenides K3SbSe3, Rb3SbSe3, and Cs3SbSe3 were de-scribed by Bronger.[7] Corresponding compounds with lithium* Prof. Dr. A. PfitznerFax: +49-941-943-814551E-Mail: arno.pfitzner@chemie.uni-regensburg.de[a] Institut für Anorganische ChemieUniversität RegensburgUniversitätsstraße 3193040 Regensburg, Germany© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 2012, 638, (12-13), 2158–21622158located at three different sites, which are all coordinated by six sele-nium atoms, providing a strongly distorted octahedral environment.NaSe6 octahedra of identical type share common vertices; in case ofdifferent sites also face sharing is observed. Na3SbSe3 shows tempera-ture dependent Na+ conductivity above 380 K, which increases to2.910–6 Ω–1 cm–1 at 590 K.and sodium are not mentioned in literature. The latter one wasalso not observed in earlier investigations of the ternary systemNa-Sb-Se by Lazarev.[8] Analogous compounds with mono-valent coinage metals are also known. Nevertheless, they differfrom alkali metal compounds in their structure like Ag3SbS3,[9]Cu3SbS3,[10,11] and Cu3SbSe3.[12] Some of them have interest-ing electric properties. Pyrargyrite Ag3SbS3, e.g., is a piezo-electric Ag+-ion conductor,[13,14] whereas Cu3SbSe3 has inter-esting thermoelectric properties.[15]Reports on electric features of alkali metal containing anti-mony chalcogenides are rather rare. Recently the ionic conduc-tivity of Li3SbS3 was verified and its bandgap was calculatedby DFT calculations.[4] Herein, we report on the preparation,structure, and physical properties of Na3SbSe3, which have notyet been described in literature.Results and DiscussionStructure Description and DiscussionThe crystal structure of Na3SbSe3 was determined by single-crystal X-ray diffraction. Crystallographic data are listed inTable 1. The compound crystallizes in space group P213. Thecell has the lattice constant a = 9.0227(2) Å, and a cell volumeof V = 734.53(3) Å3 with Z = 4. The crystal structure wasrefined to R1 = 0.0243 [22 parameters, 541 reflections withI  2σ(I)] and R2 = 0.0475 (all data). Atomic coordinates andequivalent isotropic displacement parameters Ueq are listed inTable 2, the anisotropic displacement parameters Uij inTable 3.Trigonal-pyramidal SbSe3 units are observed in Na3SbSe3(see Figure 1). The distance dprimary(Sb–Se) is 2.5778(6) Å,Na3SbSe3: Synthesis, Structure, Spectroscopy, and Ionic ConductivityTable 1. Crystallographic data for the structure analysis of Na3SbSe3.Na3SbSe3Formula weight /g·mol–1 427.60Color yellowCrystal system cubicSpace group P213 (No. 198)Lattice constant a /Å 9.0227(2)Cell volume V /Å3 734.53(3)Number of formula units per 4unit cell ZCalculated density ρcalc /g·cm–3 3.867Temperature T /K 123Wavelength λ /Å 0.71073Diffractometer Oxford Diffraction Gemini R UltraCCD, Mo-Kα (λ = 0.71073 Å)Absorption coeff. μ /mm–1 18.678Absorption correction Multi-scan[16]2Θ-range /° 6.38  2Θ  57.68hkl-ranges –7  h  12–7  k  9–11  l  11No. of reflections, Rint 1471, 0.0325No. of independent reflections 559Structure solution SIR92[17]Structure refinement SHELX-97[18]No. of parameters 22Final R, wR [I  2σ(I)] 0.0243, 0.0471Final R, wR (all reflections) 0.0259, 0.0475GooF 1.049Largest difference peak Δρmax 0.593 / –0.625and hole Δρmin /e·Å–3Flack parameter 0.01(2)Table 2. Atomic coordinates and equivalent isotropic displacement pa-rameters Ueqa) for Na3SbSe3.Atom Wyck. x y z UeqNa1 4a 0.5815(3) x x 0.018(1)Na2 4a 0.3218(3) x x 0.0136(9)Na3 4a 0.8128(3) x x 0.0124(9)Sb 4a 0.03605(4) x x 0.0085(2)Se 12b 0.23652(6) 0.61312(6) 0.50125(6) 0.0100(2)a) Ueq is defined as one third of the trace of the orthogonalized Uijtensor.and the angle Se–Sb–Se 99.67(2)°. In addition, the distancesdsecondary(Sb–Se) = 3.785 Å to next nearest neighbors shall bementioned here. A strongly distorted octahedral environmentfor antimony results when these additional selenium atoms aretaken into account. Systematic trends become obvious compar-ing these data with the analogous compounds containing theheavier alkali metals. Thus, dprimary decreases slightly fromNa3SbSe3 to Cs3SbSe3, whereas an increase of about 1.2 Å isobserved for dsecondary from the sodium containing compoundTable 3. Anisotropic displacement parameters Uij for Na3SbSe3.Atom U11 U22 U33 U23 U13 U12Na1 0.018(1) U11 U11 0.000(1) U23 U23Na2 0.0136(9) U11 U11 0.001(1) U23 U23Na3 0.0124(9) U11 U11 0.000(1) U23 U23Sb 0.0085(2) U11 U11 –0.0002(2) U23 U23Se 0.0088(3) 0.0108(3) 0.0103(3) 0.0000(2) 0.0001(2) –0.0016(2)Z. Anorg. Allg. Chem. 2012, 2158–2162 © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.zaac.wiley-vch.de 2159to the cesium homologue. In addition, an increasing angleSe–Sb–Se changing systematically from 99.67° (Na3SbSe3) to102.9° (Cs3SbSe3) is determined. A detailed analysis of theinfluence of these systematic changes on the bonding behaviorwithin the constituting SbSe3 units will be subject of a forth-coming study.Figure 1. The distorted octahedral coordination of the three sodiumsites (Na1, Na2, and Na3) is shown on the left side, distances are givenin Å. SbSe3 units form the well known trigonal pyramids (right).Sodium ions occupy three different sites (Na1, Na2, andNa3) with six-fold coordination by selenium (see Figure 1).Significant deviations from an ideal octahedral surrounding ofthe sodium ions are observed in accordance with their sitesymmetry 3, confer the distances d(Na–Se) and angles summa-rized in Table 4.Table 4. Selected interatomic distances /Å and angles /° for Na3SbSe3at 123 K.Sb–Se 3 2.5778(6) Se–Sb–Se 3 99.67(2)Na1–Se 3 3.179(3) Se–Na1–Se 3 83.54(9)3 3.208(3) Se–Na1–Se 3 85.73(9)Se–Na1–Se 3 85.91(2)Se–Na1–Se 3 107.26(1)Se–Na1–Se 3 163.95(2)Na2–Se 3 2.998(2) Se–Na2–Se 3 79.17(2)3 3.181(3) Se–Na2–Se 3 84.41(8)Se–Na2–Se 3 93.08(9)Se–Na2–Se 3 106.66(1)Se–Na2–Se 3 159.03(4)Na3–Se 3 2.992(2) Se–Na3–Se 3 75.49(8)3 3.218(3) Se–Na3–Se 3 86.92(2)Se–Na3–Se 3 92.59(9)Se–Na3–Se 3 105.90(2)Se–Na3–Se 3 161.51(7)C. Pompe, A. PfitznerARTICLEThe distances d(Na–Se) vary between 2.99 and 3.22 Å. Thisis in good accordance with effective ionic radii for Na+ =1.02 Å, and Se2– = 1.98 Å, both for a coordination numberof 6.[31] The polyhedra [NaSe6] are corner-sharing in case ofequivalent types of sodium and they form a three-dimensionalnetwork. These three resulting networks formed by Na1, Na2,and Na3 are interpenetrating and the selenoantimonate(III)units are located in between. SbSe3 units are separated fromeach other. However, they act as mono-, bi-, and tridentateligands to sodium, respectively. Thus, the different sodiumsites get a completely different environment. Na1 is coordi-nated by six monodentate SbSe3, Na2 has three bidentate li-Figure 2. Coordination of Na1 (top), Na2 (mid), and Na3 (bottom)by SbSe3 units in monodentate, bidentate and mixed tridentate andmonodentate manner.www.zaac.wiley-vch.de © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 2012, 2158–21622160gands, and Na3 is coordinated by one tridentate and threemonodentate ligands (see Figure 2).Powder X-ray DiffractionFigure 3 displays the measured diffraction pattern and thepattern calculated from single crystal structural data, demon-strating the purity of the sample obtained from the solid statereaction.Figure 3. The sample purity becomes obvious from the measured (top)and calculated X-ray powder diffraction pattern for Na3SbSe3 (down,inverted intensities).Raman SpectroscopyRaman spectroscopy is a nice tool for the estimation of bondstrengths in solid compounds, which contain molecular frag-ments. Thus, it was shown that the stretching modes of com-plex SbS3 units reveal some insight in the bonding situation ofthese units. Their vibrational bands correspond to those of thethioles Sb(SR)3 (R = C4H9, C6H5)[19] when no so called sec-ondary bonds of the SbS3 unit are present.[20–22] Contrary, ared-shift of the vibrational modes is observed for those caseswhen SbS3 units show coordination by additional sulfur atomsin distances up to about 4 Å.[23,24] The antimony atom in thetitle compound has three additional selenium atoms in its coor-dination sphere at a distance of about 3.8 Å as depicted inFigure 2. As a consequence a slight red shift of the Ramanresonances of these units is observed here in comparison to theresonances of Sb(SeMe)3.[25] As shown in Figure 4 the pro-Figure 4. Raman spectrum of the title compound.Na3SbSe3: Synthesis, Structure, Spectroscopy, and Ionic Conductivitynounced bands in the Raman spectrum are situated at 214 and194 cm–1. For Sb(SeMe)3 these bands were found at 237 and204–210 cm–1. Therein, antimony has also three additional se-lenium atoms from adjacent molecules in a similar arrange-ment as found in Na3SbSe3. However, the bonding interactionsseem to be stronger in case of the ionic sodium compound.Differential Thermal Analysis (DTA)A pure sample of Na3SbSe3 was used for DTA analysis. Themelting and crystallization process shows the typical featurefor dystectic melting, i.e., there is only one reversible maxi-mum, both in the melting and in the crystallization curve. Themelting point of Na3SbSe3 is observed at 870 K, and it crys-tallizes at 697 K (onset temperatures).Impedance MeasurementThe total electric conductivity of the title compound wasdetermined by frequency dependent impedance spectroscopy.Figure 5 shows a representative Nyquist-plot of Na3SbSe3 at586 K. The linear arc in the low frequency regime indicatesionic conductivity. An Arrhenius plot of these conductivitiesis shown in Figure 6. The activation energy is 0.69 eV. Theionic conductivity increases from 510–9 Ω–1 cm–1 at 380 Kto 310–6 Ω–1 cm–1 at 590 K. Some data from literature shallbe given herein for comparison: a very high, strong anisotropicsodium ionic conductivity is reported for β-alumina, i.e.,1.410–2 Ω–1 cm–1 at 298 K,[32] whereas, for example,Na3PS4 shows a good ionic conductivity of 4.210–6 Ω–1 cm–1at 323 K.[33]Figure 5. Impedance spectrum of Na3SbSe3 at 590 K. The spectrumshows the typical frequency dependency in case of an ionic conductorin case of blocking electrodes.Experimental SectionSynthesis: Yellow single crystals of Na3SbSe3 were prepared by an-nealing a stoichiometric mixture of Na2Se, antimony (99.9999%,Chempur) and selenium (99.999%, Chempur) in a 3:2:3 ratio at 723 Kin evacuated silica ampoules. These were coated with graphite by py-rolysis of acetone prior to use. After 10 weeks the product was slowlycooled down to room temperature. Using anhydrous Na2Se was essen-tial for a successful synthesis. This was obtained by reaction of stoi-chiometric quantities of distilled sodium (99%, Merck) and seleniumin dry ammonia.[26] Na2Se and Na3SbSe3 were handled in an atmo-sphere of argon in order to prevent decomposition due to their air andmoisture sensitivity.Z. Anorg. Allg. Chem. 2012, 2158–2162 © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.zaac.wiley-vch.de 2161Figure 6. The Arrhenius plot shows an exponential dependency of thespecific ionic conductivity on temperature.Crystal Structure Analysis: A single crystal of Na3SbSe3 was trans-ferred into a drop of mineral oil and cooled to 123 K by a stream ofnitrogen. The measurement was performed with an Oxford DiffractionGemini R Ultra CCD with Mo-Kα-radiation (λ = 0.71073 Å). Absorp-tion was corrected by multi-scans.[16] The crystal structure was solvedby direct methods with SIR92.[17] All atoms were refined with aniso-tropic displacement parameters. The Flack parameter of zero gave nohint for inversion twinning. An extinction parameter was introducedin the final stage of the refinement but it took no significant value andwas therefore disregarded.Powder X-ray Diffraction: X-ray diffraction patterns were measuredin sealed glass capillaries (diameter 0.2 mm) at room temperature. ASTOE Stadi P diffractometer with monochromatic Cu-Kα1-radiation(λ = 1.540598 Å, Ge-monochromator). Diffraction data were collectedin a 2Θ-range from 8.0° to 90° and analyzed with the STOE programpackage WINXPOW.[27]Raman Spectroscopy: The powdered sample in a sealed glass capil-lary (diameter 0.5 mm) was excited by a Nd:YAG laser (λ = 1064 nm)in a Varian FTS 7000e Spectrometer coupled to a Varian FT-Ramanmodule. A liquid nitrogen cooled germanium detector was used inback-scattering mode. Scattering intensities were finally evaluated bythe software Varian resolutions Pro.[28]Thermal Analysis: The thermal behavior was investigated by per-forming DTA with a Setaram DTA-TG 92–16.18. A small amount ofthe powdered sample was filled in a capillary tube (diameter 1.5 mm)and sealed in an argon atmosphere. The tube was heated up from 298to 1073 K and cooled down again to room temperature with a heating/cooling rate of 10 K·min–1. Al2O3 was used as an external standard.Onset temperatures of the melting and crystallization process are de-rived from the respective curves.Impedance Spectroscopy: A powdered sample of Na3SbSe3 waspressed 20 min with a pressure of 7000 kg·cm–2 to a pellet with 92%of the calculated density. It was inserted between thin plates of goldas blocking electrodes. Frequencies ranged from 1 Hz to 1 MHz andtemperatures from 373 K to 573 K (IMd6, Zahner Elektrik). The datawere evaluated with the software Thales Flink.[29] Details of the setupare given elsewhere.[30]Further details of the crystal structure investigations may be obtainedfrom the Fachinformationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany (Fax: +49-7247-808-666; E-Mail:crysdata@fiz-karlsruhe.de, http://www.fiz-karlsruhe.de/request for de-posited data.html) on quoting the depository number CSD-425125.C. Pompe, A. PfitznerARTICLEAcknowledgementsWe thank Dr. M. Bodensteiner for collecting single-crystal X-ray dif-fraction data.References[1] H. Sommer, R. Hoppe, Z. Anorg. Allg. Chem. 1977, 480, 199.[2] M. Palazzi, Acta Crystallogr., Sect. B 1976, 32, 3175.[3] W. Bronger, A. Donike, D. Schmitz, Z. Anorg. Allg. Chem. 1997,623, 1715.[4] S. Huber, C. Preitschaft, R. Weihrich, A. Pfitzner, Z. Anorg. Allg.Chem. 2012, published online, DOI:10.1002/zaac.201200277.[5] J. Lin, G. J. Miller, J. Solid State Chem. 1994, 113, 296.[6] B. Eisenmann, R. Zagler, Z. Kristallogr. 1991, 197, 255.[7] W. Bronger, A. Donike, D. Schmitz, Z. Anorg. Allg. Chem. 1999,625, 435.[8] V. B. Lazarev, A. V. Salov, I. S. Shaplygin, Russ. J. Inorg. Chem.1977, 22, 246.[9] D. Harker, J. Chem. Phys. 1936, 4, 381.[10] A. Pfitzner, Z. Anorg. Allg. Chem. 1994, 620, 1992.[11] A. Pfitzner, Z. Kristallogr. 1998, 213, 228.[12] A. Pfitzner, Z. Anorg. Allg. Chem. 1995, 621, 685.[13] N. V. Morozovskii, Ukr. Khim. Zh. (Russ. Ed.). 1981, 47, 1043.[14] M. Leitl, Dissertation, Universität Regensburg, Germany 2007.[15] M. Kirkham, P. Majsztrik, E. Skoug, D. Morelli, H. Wang, W. D.Porter, E. A. Payzant, E. Lara-Curzio, J. Mater. Res. 2011, 26,2001.[16] SCALE3 ABSPACK, CrysAlis RED software, Version 171.35.21;Oxford Diffraction Ltd: Oxford, UK, 2006.www.zaac.wiley-vch.de © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 2012, 2158–21622162[17] A. Altomare, M. C. Burla, M. Camalli, G. Cascarano, C. Giacov-azzo, A. Guagliardi, G. Polidori, J. Appl. Crystallogr. 1994, 27,435.[18] G. M. Sheldrick, SHELX 97 Programs for Solution and Refinementof Crystal structures, University of Göttingen, Germany, 1997.[19] J. Weidlein, U. Müller, K. Dehnicke, Schwingungsfrequenzen I,Thieme, Stuttgart, 1981, 155.[20] A. Pfitzner, Chem. Eur. J. 1997, 3, 2032.[21] T. Nilges, S. Reiser, J. H. Hong, E. Gaudin, A. Pfitzner, Phys.Chem. Chem. Phys. 2002, 4, 5888.[22] K. Möller, C. Näther, A. Bannwarth, W. Bensch, Z. Anorg. Allg.Chem. 2007, 633, 2635.[23] A. Pfitzner, D. Kurowski, Z. Kristallogr. 2000, 215, 373.[24] E. Quiroga-González, C. Näther, W. Bensch, Z. Naturforsch. B2009, 64, 1312.[25] H. J. Breunig, S. Gülec, B. Krebs, M. Dartmann, Z. Naturforsch.B 1989, 44, 1351.[26] W. Klemm, H. Sodomann, P. Langmesser, Z. Anorg. Allg. Chem.1939, 241, 281.[27] STOE, WinXPOW, Version 1.08, STOE & Cie GmbH, Darmstadt,2000.[28] Varian resolutions pro, Version 4.1.0.101, Varian, Inc., 2006.[29] Thales Flink, Version 2.13; Zahner Meßtechnik GmbH & Co. KG,Kronach.[30] E. Freudenthaler, A. Pfitzner, Solid State Ionics 1997, 101–103,1053.[31] R. D. Shannon, Acta Crystallogr., Sect. A 1976, 32, 751.[32] M. S. Whittingham, R. A. Huggins, J. Chem. Phys. 1971, 54, 414.[33] M. Jansen, U. Henseler, J. Solid State Chem. 1992, 99, 110.Received: August 14, 2012Published Online: October 8, 2012

Na3SbSe3: Synthesis, Crystal Structure Determination, Raman-Spectroscopy, and Ionic Conductivity

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Na3SbSe3: Synthesis, Crystal Structure Determination, Raman-Spectroscopy, and Ionic Conductivity

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