B14Ho4Ni, tetragonal, P4/mnc (No. 128), a = 7.2097(8) Å, c = 7.4587(9) Å, V = 387.7 Å3, Z = 2, Rgt(F) = 0.049, wRref(F2) = 0.087, T = 300 K

Geupel, S.

Graw, G.

Paufler, P.

Zahn, G.

English

Repositorium für Naturwissenschaften und Technik

Ζ. Kristallogr. NCS 216 (2001) 175-176 1 7 5 © by Oldenbourg Wissenschaftsverlag. München Crystal structure of tetraholmium nickel tetradecaboride, H 0 4 N 1 B 1 4 S. G e u p e l * ' G . Zahn1, P. Paufler1 and G. Graw" 1 Technische Universität Dresden. Institut für Kristallographie und Festkörperphysik. D-01062 Dresden. Germany " Institut für Festkörper- und Werkstofforschung Dresden. Postfach 270016. D-01171 Dresden. Germany Received October 9. 2000. CSD-No. 409535 to-minimum axis ratio for the displacement tensor of Ni, while the displacement ellipsoids of Β1 and B2 became non-positive definite. Discussion Lattice parameters and atomic coordinates of H04N1B14 are closely related to those of the previously studied compound Er4NiBi3 [3], However, the difference Fourier synthesis based of our more extended single-crystal data set ((sinOmax)^ = 0.66) shows unambiguously, that the B3 atom not occupies the Wyckoff site 26(0,0,1/2), but 4e(0,0,z) with free ζ parameter, re-sulting in the stoichiometry Ho4NiBi4 instead of Ηθ4ΝίΒΐ3· The crystal structure of Ho4NiBi4 (P4/mnc - ihgea) is characterized by an alternate stacking of planar Ho-Ni layers and slightly corru-gated Β1-B2 layers perpendicular to the c axis. The Β1-B2 layers are linked via dumbbells of B3 atoms lying above and below the Ho-Ni layers. Each B3 atom is square-pyramidally surrounded by Β1 atoms at 1.72 Ä as well as Ho atoms at 2.66 Ä. The coordina-tion number of Ni atoms is 12. Their coordination polyhedron consists of a square plane of Ho atoms (Ni—Ho distance 2.770 Ä) and two square pyramids of Β1 atoms (Ni—Β1 distance 2.17 Ä). Abstract B14H04N1, tetragonal, PA/mnc (No. 128), a = 7.2097(8) Ä, c = 7.4587(9) Ä, V = 387.7 Ä3, Ζ = 2, R&(F) = 0.049, wRK,iF2) = 0.087, 7 = 300 K. Source of material A single-crystalline piece of the title compound has been extrac-ted from a coarse-grained ternary alloy with nominal composition H02N13B6. The latter was prepared from a stoichiometric mixture of holmium pieces, nickel powder and boron powder by arc-melting and subsequent annealing (duration 75 h, tempera-ture up to 1733 K) within a resistance furnace under argon atmo-sphere. Electron probe microanalysis confirmed the presence of a ternary phase with approximate stoichiometry H04N1B13 in addi-tion to the main phase H02N13B6 [1]. Experimental details Atomic coordinates of H04N1B14 correspond to the standardized form according to [2]. Any attempts to refine Ni and Β atoms anisotropically resulted in an unreasonable large maximum-Table 1. Data collection and handling. Crystal: metallic block. size 0.020 χ 0.040 χ 0.080 mm Wavelength: Mo Ka radiation (0.71073 A) μ: 426.42 cm"1 Diffractometer, scan mode: Stoe IPDS, 186 frames, Δφ = 1° 20max: 55.74° Wfc/jmeasured, N(hkl)u„ique: 2930,246 Criterion for /0bs, N(hkl)gC. U s > 2 af/obJ, 209 N(param)le fined: 17 Programs: SHELXS-97 [4], SHELXL-97 [5], XABS2 [6], SCHAKAL 97 [7] Table 2. Atomic coordinates and displacement parameters (in Ä2). Atom Site la 16/ Ni B(l) B(2) B(3) 4e 0 0 0.175(3) 0.042(2) 0.089(3) 1/2 + χ 0 0 0 0.003(1) 0.234(2) 0.006(3) 1/4 0.008(4) 0.386(6) 0.011(7) Table 3. Atomic coordinates and displacement parameters (in A2). Atom Site χ y ζ U\\ U22 C/33 U12 U13 f/23 Ho 8/1 0.1939(1) 0.3317(1) 0 0.0052(6) U11 0.0042(5) -0.0004(4) 0 0 * Correspondence author (e-mail: sandra.geupel@uni-bayreuth.de) 1 Current address: Universität Bayreuth, Lehrstuhl für Kristallographie, D-95440 Bayreuth, Germany. 176 Tetraholmium nickel tetradecaboride Acknowledgment. Support by the Deutsche Forschungsgemeinschaft is grate-fully acknowledged. References 1. Geupel. S.; Zahn, G.: Paufler. P.: Graw, G.: Refinement of the crystal structure of diholmium trinickel hexaboride. Ho:NijB6. Z. Kristallogr. NCS 215 (2000) 477-478. 2. Gelato, L. M.; Paithi, E.: STRUCTURE TIDY - a computer program to standardize crystal structure data. J. Appl. Crystallogr. 20 (1987) 139-143. 3. Kuz'ma, Yu. B.: Chemyak,G. V.; Aksel'rud, L. G.; Kotur. B.Ya.; Chaban. N.F.: Crystal structure of the boride ErjNiBu and its analogs. Sov. Phys. Crystallogr. 28(1983)711-713. 4 Sheldrick. G. M.: Phase annealing in SHELXS-90. Direct methods for larger structures. Acta Crystallogr. A46 (1990) 467-473. 5. Sheldrick. G. M.: SHELXS-97. Program for the Solution of Crystal Struc-tures. University of Göttingen. Germany 1997. 6. Parkin, S.; Moezzi. B.: Hope, H.: XABS2: an empirical absorption correc-tion program. J. Appl. Crystallogr. 28 (1995) 53-56. 7. Keller, E.: SCHAKAL 97, computer program for the graphic representa-tion of molecular and crystallographic models. University of Freiburg. Germany 1997. 

Crystal structure of tetraholmium nickel tetradecaboride, Ho4NiB14

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Crystal structure of tetraholmium nickel tetradecaboride, Ho4NiB14

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