Acta Cryst. (2013). E69, i17 [ doi:10.1107/S1600536813003541 ]
Barium dierbium(III) tetrasulfide, BaEr2S4, crystallizes with four formula units in the orthorhombic space group Pnma in the CaFe2O4 structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS6 octahedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism.
In an exploration of the quaternary solid-state Ba/Er/U/S system, orange needles of BaEr2S4 were obtained instead in a two-step reaction. Uranium powder was obtained by hydridization and decomposition of 238U turnings (Oak Ridge National Laboratory) (Bugaris & Ibers, 2008; Haneveld & Jellinek, 1969). The other reactants were used as obtained. In the first step, a mixture consisting of powdered 238U (20.9 mg, 0.088 mmol), Er (14.0 mg, 0.084 mmol), BaS (42.7 mg, 0.252 mmol), and S (8.0 mg, 0.25 mmol) was loaded into a carbon-coated fused-silica tube under an Ar atmosphere in a glove box. The tube was evacuated to 10 -4 Torr, and flame sealed. It was placed in computer-contolled furnace, heated to 1273 K in 48 h, held there for 8 d, then cooled to 293 K at 3 K/h. In the second step, the resultant black powder was ground and mixed thoroughly with 50 mg of Sb2S3. This mixture was re-loaded into a carbon-coated fused-silica tube, evacuated, sealed, and then placed in a computer-controlled furnace The tube was heated to 1273 K in 24 h, held there for 4 d, then cooled to 293 K at 2 K/h. Orange needles were obtained in about 50 wt% yield. Analysis of these orange crystals on an EDX– equipped Hitachi S-3400 SEM showed the presence of Ba, Er, and S in the approximate ratio 1:2:4 but no U. The other products were black crystals of Sb2S3 and US2.
The structure was standardized by means of the program STRUCTURE TIDY ((Gelato & Parthé, 1987). The highest peak in the difference electron density map (2.46 e. Å-3) was 0.47 Å from atom Er1 and the deepest hole (- 2.58 e. Å-3) was 0.20 Å from atom Ba1.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: CrystalMaker (Palmer, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008b).
![[Figure 1]](./br2222fig1thm.gif)
| Fig. 1. Structure of BaEr2S4 viewed approximatly down [010]. Displacement ellipsoids are drawn at 95% probability level. |
| BaEr2S4 | F(000) = 1024 |
| Mr = 600.10 | Dx = 5.721 Mg m−3 |
| Orthorhombic, Pnma | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ac 2n | Cell parameters from 8150 reflections |
| a = 12.1455 (3) Å | θ = 2.3–30.5° |
| b = 3.9884 (1) Å | µ = 30.53 mm−1 |
| c = 14.3837 (4) Å | T = 100 K |
| V = 696.76 (3) Å3 | Needle, orange |
| Z = 4 | 0.16 × 0.03 × 0.02 mm |
| Bruker APEXII CCD diffractometer | 1207 independent reflections |
| Radiation source: fine-focus sealed tube | 1196 reflections with I > 2σ(I) |
| Graphite monochromator | Rint = 0.030 |
| φ and ω scans | θmax = 30.5°, θmin = 2.2° |
| Absorption correction: numerical face indexed (Sheldrick, 2008a) | h = −17→17 |
| Tmin = 0.084, Tmax = 0.528 | k = −5→5 |
| 9866 measured reflections | l = −20→20 |
| Refinement on F2 | Primary atom site location: structure-invariant direct methods |
| Least-squares matrix: full | Secondary atom site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.017 | 1/[s2(Fo2) + (0.0192Fo2)2] |
| wR(F2) = 0.050 | (Δ/σ)max = 0.002 |
| S = 1.87 | Δρmax = 2.46 e Å−3 |
| 1207 reflections | Δρmin = −2.58 e Å−3 |
| 44 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008a), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| 0 restraints | Extinction coefficient: 0.00257 (16) |
| BaEr2S4 | V = 696.76 (3) Å3 |
| Mr = 600.10 | Z = 4 |
| Orthorhombic, Pnma | Mo Kα radiation |
| a = 12.1455 (3) Å | µ = 30.53 mm−1 |
| b = 3.9884 (1) Å | T = 100 K |
| c = 14.3837 (4) Å | 0.16 × 0.03 × 0.02 mm |
| Bruker APEXII CCD diffractometer | 1207 independent reflections |
| Absorption correction: numerical face indexed (Sheldrick, 2008a) | 1196 reflections with I > 2σ(I) |
| Tmin = 0.084, Tmax = 0.528 | Rint = 0.030 |
| 9866 measured reflections | θmax = 30.5° |
| R[F2 > 2σ(F2)] = 0.017 | Δρmax = 2.46 e Å−3 |
| wR(F2) = 0.050 | Δρmin = −2.58 e Å−3 |
| S = 1.87 | Absolute structure: ? |
| 1207 reflections | Flack parameter: ? |
| 44 parameters | Rogers parameter: ? |
| 0 restraints |
| x | y | z | Uiso*/Ueq | ||
| Er1 | 0.079448 (16) | 0.2500 | 0.398817 (12) | 0.00349 (8) | |
| Er2 | 0.566211 (16) | 0.2500 | 0.608465 (12) | 0.00444 (8) | |
| Ba1 | 0.24191 (2) | 0.2500 | 0.662667 (18) | 0.00705 (9) | |
| S1 | 0.08229 (8) | 0.2500 | 0.07671 (7) | 0.00485 (18) | |
| S2 | 0.29294 (9) | 0.2500 | 0.33808 (7) | 0.00537 (18) | |
| S3 | 0.37564 (8) | 0.2500 | 0.02341 (7) | 0.00449 (18) | |
| S4 | 0.47727 (8) | 0.2500 | 0.78311 (7) | 0.00490 (18) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Er1 | 0.00359 (11) | 0.00300 (12) | 0.00388 (11) | 0.000 | 0.00010 (5) | 0.000 |
| Er2 | 0.00495 (12) | 0.00349 (12) | 0.00487 (11) | 0.000 | −0.00020 (5) | 0.000 |
| Ba1 | 0.00595 (14) | 0.00835 (14) | 0.00683 (13) | 0.000 | 0.00015 (8) | 0.000 |
| S1 | 0.0057 (4) | 0.0040 (4) | 0.0049 (4) | 0.000 | −0.0004 (3) | 0.000 |
| S2 | 0.0037 (4) | 0.0044 (4) | 0.0080 (4) | 0.000 | −0.0006 (3) | 0.000 |
| S3 | 0.0046 (4) | 0.0037 (4) | 0.0052 (4) | 0.000 | 0.0009 (3) | 0.000 |
| S4 | 0.0061 (4) | 0.0039 (4) | 0.0047 (4) | 0.000 | 0.0015 (3) | 0.000 |
| Er1—S4i | 2.6872 (6) | Ba1—S4 | 3.3426 (11) |
| Er1—S4ii | 2.6872 (6) | Ba1—Er2x | 3.9231 (3) |
| Er1—S3iii | 2.7164 (10) | Ba1—Ba1xi | 3.9884 (1) |
| Er1—S3iv | 2.7360 (7) | Ba1—Ba1xii | 3.9884 |
| Er1—S3v | 2.7360 (7) | S1—Er2iii | 2.6706 (10) |
| Er1—S2 | 2.7362 (11) | S1—Er2i | 2.7273 (7) |
| Er1—Ba1 | 4.2774 (3) | S1—Er2ii | 2.7273 (7) |
| Er2—S1vi | 2.6706 (10) | S1—Ba1ii | 3.1725 (8) |
| Er2—S1v | 2.7274 (7) | S1—Ba1i | 3.1725 (8) |
| Er2—S1iv | 2.7274 (7) | S2—Er2vii | 2.7376 (7) |
| Er2—S4 | 2.7345 (9) | S2—Er2viii | 2.7376 (7) |
| Er2—S2vii | 2.7376 (7) | S2—Ba1i | 3.2437 (9) |
| Er2—S2viii | 2.7376 (7) | S2—Ba1ii | 3.2437 (9) |
| Er2—Ba1ix | 3.9231 (3) | S3—Er1vi | 2.7163 (10) |
| Er2—Ba1 | 4.0153 (3) | S3—Er1i | 2.7360 (7) |
| Ba1—S3v | 3.1666 (8) | S3—Er1ii | 2.7360 (7) |
| Ba1—S3iv | 3.1666 (8) | S3—Ba1ii | 3.1666 (8) |
| Ba1—S1iv | 3.1725 (8) | S3—Ba1i | 3.1666 (8) |
| Ba1—S1v | 3.1725 (8) | S4—Er1iv | 2.6873 (6) |
| Ba1—S2iv | 3.2438 (9) | S4—Er1v | 2.6873 (6) |
| Ba1—S2v | 3.2438 (9) | S4—Ba1ix | 3.3074 (11) |
| Ba1—S4x | 3.3074 (11) | ||
| S4i—Er1—S4ii | 95.82 (3) | S3iv—Ba1—Er2x | 106.592 (19) |
| S4i—Er1—S3iii | 91.23 (3) | S1iv—Ba1—Er2x | 133.879 (16) |
| S4ii—Er1—S3iii | 91.23 (3) | S1v—Ba1—Er2x | 133.879 (16) |
| S4i—Er1—S3iv | 176.07 (3) | S2iv—Ba1—Er2x | 43.642 (15) |
| S4ii—Er1—S3iv | 85.17 (2) | S2v—Ba1—Er2x | 43.642 (15) |
| S3iii—Er1—S3iv | 84.95 (3) | S4x—Ba1—Er2x | 43.408 (16) |
| S4i—Er1—S3v | 85.17 (2) | S4—Ba1—Er2x | 91.735 (18) |
| S4ii—Er1—S3v | 176.07 (3) | S3v—Ba1—Ba1xi | 129.032 (11) |
| S3iii—Er1—S3v | 84.95 (3) | S3iv—Ba1—Ba1xi | 50.967 (11) |
| S3iv—Er1—S3v | 93.58 (3) | S1iv—Ba1—Ba1xi | 51.054 (12) |
| S4i—Er1—S2 | 92.59 (3) | S1v—Ba1—Ba1xi | 128.946 (12) |
| S4ii—Er1—S2 | 92.59 (3) | S2iv—Ba1—Ba1xi | 52.064 (12) |
| S3iii—Er1—S2 | 174.30 (3) | S2v—Ba1—Ba1xi | 127.936 (12) |
| S3iv—Er1—S2 | 91.16 (3) | S4x—Ba1—Ba1xi | 90.0 |
| S3v—Er1—S2 | 91.16 (3) | S4—Ba1—Ba1xi | 90.0 |
| S4i—Er1—Ba1 | 131.894 (15) | Er2x—Ba1—Ba1xi | 90.0 |
| S4ii—Er1—Ba1 | 131.894 (15) | S3v—Ba1—Ba1xii | 50.967 (11) |
| S3iii—Er1—Ba1 | 93.15 (2) | S3iv—Ba1—Ba1xii | 129.032 (11) |
| S3iv—Er1—Ba1 | 47.693 (15) | S1iv—Ba1—Ba1xii | 128.946 (12) |
| S3v—Er1—Ba1 | 47.693 (15) | S1v—Ba1—Ba1xii | 51.054 (12) |
| S2—Er1—Ba1 | 81.15 (2) | S2iv—Ba1—Ba1xii | 127.936 (12) |
| S1vi—Er2—S1v | 83.18 (3) | S2v—Ba1—Ba1xii | 52.064 (12) |
| S1vi—Er2—S1iv | 83.18 (3) | S4x—Ba1—Ba1xii | 90.0 |
| S1v—Er2—S1iv | 93.97 (3) | S4—Ba1—Ba1xii | 90.0 |
| S1vi—Er2—S4 | 160.92 (3) | Er2x—Ba1—Ba1xii | 90.0 |
| S1v—Er2—S4 | 83.84 (3) | Ba1xi—Ba1—Ba1xii | 180.0 |
| S1iv—Er2—S4 | 83.84 (3) | S3v—Ba1—Er2 | 108.630 (19) |
| S1vi—Er2—S2vii | 103.56 (3) | S3iv—Ba1—Er2 | 108.630 (19) |
| S1v—Er2—S2vii | 173.17 (3) | S1iv—Ba1—Er2 | 42.616 (14) |
| S1iv—Er2—S2vii | 85.85 (2) | S1v—Ba1—Er2 | 42.616 (14) |
| S4—Er2—S2vii | 89.36 (3) | S2iv—Ba1—Er2 | 106.201 (19) |
| S1vi—Er2—S2viii | 103.56 (3) | S2v—Ba1—Er2 | 106.201 (19) |
| S1v—Er2—S2viii | 85.85 (2) | S4x—Ba1—Er2 | 177.557 (18) |
| S1iv—Er2—S2viii | 173.17 (3) | S4—Ba1—Er2 | 42.413 (17) |
| S4—Er2—S2viii | 89.36 (3) | Er2x—Ba1—Er2 | 134.149 (8) |
| S2vii—Er2—S2viii | 93.51 (3) | Ba1xi—Ba1—Er2 | 90.0 |
| S1vi—Er2—Ba1ix | 142.85 (2) | Ba1xii—Ba1—Er2 | 90.0 |
| S1v—Er2—Ba1ix | 120.02 (2) | Er2iii—S1—Er2i | 96.82 (3) |
| S1iv—Er2—Ba1ix | 120.02 (2) | Er2iii—S1—Er2ii | 96.82 (3) |
| S4—Er2—Ba1ix | 56.22 (2) | Er2i—S1—Er2ii | 93.97 (3) |
| S2vii—Er2—Ba1ix | 54.861 (19) | Er2iii—S1—Ba1ii | 115.97 (3) |
| S2viii—Er2—Ba1ix | 54.861 (19) | Er2i—S1—Ba1ii | 147.08 (4) |
| S1vi—Er2—Ba1 | 105.39 (2) | Er2ii—S1—Ba1ii | 85.422 (12) |
| S1v—Er2—Ba1 | 51.961 (18) | Er2iii—S1—Ba1i | 115.97 (3) |
| S1iv—Er2—Ba1 | 51.961 (18) | Er2i—S1—Ba1i | 85.422 (12) |
| S4—Er2—Ba1 | 55.53 (2) | Er2ii—S1—Ba1i | 147.08 (4) |
| S2vii—Er2—Ba1 | 123.95 (2) | Ba1ii—S1—Ba1i | 77.89 (2) |
| S2viii—Er2—Ba1 | 123.95 (2) | Er1—S2—Er2vii | 120.17 (3) |
| Ba1ix—Er2—Ba1 | 111.755 (5) | Er1—S2—Er2viii | 120.17 (3) |
| S3v—Ba1—S3iv | 78.06 (2) | Er2vii—S2—Er2viii | 93.51 (3) |
| S3v—Ba1—S1iv | 116.92 (2) | Er1—S2—Ba1i | 97.16 (3) |
| S3iv—Ba1—S1iv | 70.19 (2) | Er2vii—S2—Ba1i | 138.40 (4) |
| S3v—Ba1—S1v | 70.19 (2) | Er2viii—S2—Ba1i | 81.498 (14) |
| S3iv—Ba1—S1v | 116.92 (2) | Er1—S2—Ba1ii | 97.16 (3) |
| S1iv—Ba1—S1v | 77.89 (2) | Er2vii—S2—Ba1ii | 81.498 (14) |
| S3v—Ba1—S2iv | 145.12 (3) | Er2viii—S2—Ba1ii | 138.40 (4) |
| S3iv—Ba1—S2iv | 92.639 (19) | Ba1i—S2—Ba1ii | 75.87 (2) |
| S1iv—Ba1—S2iv | 90.26 (2) | Er1vi—S3—Er1i | 95.05 (3) |
| S1v—Ba1—S2iv | 141.02 (3) | Er1vi—S3—Er1ii | 95.05 (3) |
| S3v—Ba1—S2v | 92.639 (19) | Er1i—S3—Er1ii | 93.58 (3) |
| S3iv—Ba1—S2v | 145.12 (3) | Er1vi—S3—Ba1ii | 98.65 (3) |
| S1iv—Ba1—S2v | 141.02 (3) | Er1i—S3—Ba1ii | 164.41 (4) |
| S1v—Ba1—S2v | 90.26 (2) | Er1ii—S3—Ba1ii | 92.590 (8) |
| S2iv—Ba1—S2v | 75.87 (2) | Er1vi—S3—Ba1i | 98.65 (3) |
| S3v—Ba1—S4x | 73.20 (2) | Er1i—S3—Ba1i | 92.590 (8) |
| S3iv—Ba1—S4x | 73.20 (2) | Er1ii—S3—Ba1i | 164.41 (4) |
| S1iv—Ba1—S4x | 138.242 (15) | Ba1ii—S3—Ba1i | 78.07 (2) |
| S1v—Ba1—S4x | 138.242 (15) | Er1iv—S4—Er1v | 95.82 (3) |
| S2iv—Ba1—S4x | 71.93 (2) | Er1iv—S4—Er2 | 132.085 (15) |
| S2v—Ba1—S4x | 71.93 (2) | Er1v—S4—Er2 | 132.085 (15) |
| S3v—Ba1—S4 | 135.514 (16) | Er1iv—S4—Ba1ix | 95.91 (3) |
| S3iv—Ba1—S4 | 135.514 (16) | Er1v—S4—Ba1ix | 95.91 (3) |
| S1iv—Ba1—S4 | 68.06 (2) | Er2—S4—Ba1ix | 80.37 (3) |
| S1v—Ba1—S4 | 68.06 (2) | Er1iv—S4—Ba1 | 95.84 (3) |
| S2iv—Ba1—S4 | 73.05 (2) | Er1v—S4—Ba1 | 95.84 (3) |
| S2v—Ba1—S4 | 73.05 (2) | Er2—S4—Ba1 | 82.05 (3) |
| S4x—Ba1—S4 | 135.144 (10) | Ba1ix—S4—Ba1 | 162.42 (3) |
| S3v—Ba1—Er2x | 106.592 (19) |
| Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) −x+1/2, −y+1, z−1/2; (iii) x−1/2, y, −z+1/2; (iv) −x+1/2, −y+1, z+1/2; (v) −x+1/2, −y, z+1/2; (vi) x+1/2, y, −z+1/2; (vii) −x+1, −y+1, −z+1; (viii) −x+1, −y, −z+1; (ix) x+1/2, y, −z+3/2; (x) x−1/2, y, −z+3/2; (xi) x, y+1, z; (xii) x, y−1, z. |
The research was kindly supported at Northwestern University by the US Department of Energy, Basic Energy Sciences, Chemical Sciences, Biosciences, and Geosciences Division and Division of Materials Science and Engineering Grant ER-15522. Use was made of the IMSERC X-ray Facility at Northwestern University, supported by the International Institute of Nanotechnology (IIN).
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Orange needles of BaEr2S4 were obtained in a solid-state reaction. The compound was synthesized previously (Patrie et al., 1964), and its unit cell parameters were determined from X-powder diffraction data. In the BaLn2S4 family (Ln = rare earth element) no structures have been determined from single-crystal data but that of the closely related compound BaLu2S4 has (Schurz & Schleid, 2011). Here, from X-ray diffraction single-crystal data we find that BaEr2S4 crystallizes in the CaFe2O4 structure type (Decker & Kasper, 1957) with four formula units in space group Pnma of the orthorhombic system. In the asymmetric unit there are two Er, one Ba, and four S atoms, each with site symmetry .m.. A projection of the structure down [010] is shown in Figure 1. The structure consists of ErS6 octahedra that form dimers by edge-sharing. Four such dimers form an infinite channel by corner-sharing in the (010) plane. Each channel is filled by one Ba atom. Each Er1 atom is octahedrally coordinated to one S2, three S3, and two S4 atoms; each Er2 atom is coordinated to three S1, two S2, and one S4 atom. The interatomic Er - S distances at 2.6706 (10) to 2.7376 (7) Å compare favorably to those of 2.672 (4) to 2.720 (4) Å in the structure of BaLu2S4 (Schurz & Schleid, 2011). As there are no S - S bonds in the structure, formal oxidation states may be assigned as Ba2+, Er3+, and S2-.