Redetermination of dysprosium trinickel from single-crystal X-ray data

Volodymyr Levytskyy; Volodymyr Babizhetskyy; Bohdan Kotur; Volodymyr Smetana

doi:10.1107/S1600536812043747

. 2012 Oct 27;68(Pt 11):i83. doi: 10.1107/S1600536812043747

Redetermination of dysprosium trinickel from single-crystal X-ray data

Volodymyr Levytskyy ^a,^*, Volodymyr Babizhetskyy ^a, Bohdan Kotur ^a, Volodymyr Smetana ^b

PMCID: PMC3515086 PMID: 23284313

Abstract

The crystal structure of the title compound, DyNi₃, was redetermined from single-crystal X-ray diffraction data. In comparison with previous studies based on powder X-ray diffraction data [Lemaire & Paccard (1969 ▶). Bull. Soc. Fr. Minéral. Cristallogr. 92, 9–16; Tsai et al. (1974 ▶). J. Appl. Phys. 45, 3582–3586], the present redetermination revealed refined coordinates and anisotropic displacement parameters for all atoms. The crystal structure of DyNi₃ adopts the PuNi₃ structure type and can be derived from the CaCu₅ structure type as an intergrowth structure. The asymmetric unit contains two Dy sites (site symmetries 3m and -3) and three Ni sites (m, 3m and -3m). The two different coordination polyhedra of Dy are a Frank–Kasper polyhedron formed by four Dy and 12 Ni atoms and a pseudo-Frank–Kasper polyhedron formed by two Dy and 18 Ni atoms. The three different coordination polyhedra of Ni are Frank–Kasper icosahedra formed by five Dy and seven Ni atoms, three Dy and nine Ni atoms, and six Dy and six Ni atoms.

Related literature

For the PuNi₃ structure type, see: Cromer & Olsen (1959 ▶). For previous powder diffraction studies of the title compoud, see: Paccard & Pauthenet (1967 ▶); Lemaire & Paccard (1969 ▶); Virkar & Raman (1969 ▶); Buschow & van der Goot (1970 ▶); Yakinthos & Paccard (1972 ▶); Tsai et al. (1974 ▶). For related compounds, see: Virkar & Raman (1969 ▶); Buschow & van der Goot (1970 ▶); Levytskyy et al. (2012 ▶). For the CaCu₅ structure type, see: Haucke (1940 ▶); Nowotny (1942 ▶). For the MgCu₂ structure type, see: Friauf (1927 ▶); Ohba et al. (1984 ▶). For intergrowth structures, see: Parthé et al. (1985 ▶); Grin (1992 ▶).

Experimental

Crystal data

DyNi₃
M _r = 338.63
Trigonal,
a = 4.966 (2) Å
c = 24.37 (1) Å
V = 520.5 (4) Å³
Z = 9
Mo Kα radiation
μ = 55.52 mm⁻¹
T = 293 K
0.13 × 0.08 × 0.06 mm

Data collection

Stoe IPDS II diffractometer
Absorption correction: multi-scan (PLATON, Spek, 2009 ▶) T _min = 0.071, T _max = 0.182
1516 measured reflections
197 independent reflections
163 reflections with I > 2σ(I)
R _int = 0.058

Refinement

R[F ² > 2σ(F ²)] = 0.022
wR(F ²) = 0.043
S = 1.01
197 reflections
17 parameters
Δρ_max = 2.77 e Å⁻³
Δρ_min = −1.33 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2009 ▶); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SIR2011 (Burla et al., 2012 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and WinGX (Farrugia, 1999 ▶); molecular graphics: DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(24.9KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812043747/wm2688sup1.cif

e-68-00i83-sup1.cif^{(24.9KB, cif)}

Click here for additional data file.^{(10.8KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812043747/wm2688Isup2.hkl

e-68-00i83-Isup2.hkl^{(10.8KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

The existence of the intermetallic phase with composition DyNi₃ has been long known before. The first structure report (Paccard & Pauthenet, 1967) of the title compound revealed isotypism with the PuNi₃ structure type (Cromer & Olsen, 1959). Lattice parameters were determined from X-ray powder diffraction data without specifying atomic coordinates (Paccard & Pauthenet, 1967; Lemaire & Paccard, 1969; Virkar & Raman, 1969; Buschow & van der Goot, 1970; Tsai et al., 1974). Yakinthos & Paccard (1972) reported crystal structure data for RNi₃ compounds (R = Pr, Nd, Tb, Dy, Tm) from powder neutron diffraction data.

The present work contains the results of the full single-crystal X-ray determination of DyNi₃, including refinement of the atomic coordinates and the temperature factors for all atoms. These results confirm the belonging to the PuNi₃ structure type in space group R3m. A view of the crystal structure of DyNi₃ is shown in Fig. 1. As has been noted previously (Yakinthos & Paccard, 1972), the crystal structure of DyNi₃ can be derived from the CaCu₅ structure type (Haucke, 1940; Nowotny, 1942). It consists of stacks of RX₅ blocks (CaCu₅-type) and R₂X₄ blocks (MgCu₂-type (Friauf, 1927; Ohba et al., 1984)). Both types have the same Kagome net of Ni atoms that allows a combination of both structural motifs along the 3-fold inversion axis. As a result, it can be considered as an intergrowth structure: R₂X₄ + RX₅ = 3RX₃ (Parthé et al., 1985; Grin, 1992).

In Fig. 2 the projection of the unit cell on the ab plane and the resulting coordination polyhedra for all atom types are shown. The coordination number for the Dy1 atom (Wyckoff site 6c, site symmetry 3m). The coordination polyhedron for this atom is a Frank-Kasper polyhedron formed by 4 Dy and 12 Ni atoms. The coordination number for the Dy2 atom (Wyckoff site 3a, site symmetry 3m) is 20. The coordination polyhedron of Dy2 is a pseudo-Frank-Kasper polyhedron formed by 2 Dy and 18 Ni atoms. Although the site symmetries for all Ni atoms are different, the coordination number for all Ni atoms is 12, with Frank-Kasper icosahedra as coordination polyhedra. The Ni1 atom (Wyckoff site 18h, site symmetry .m) is surrounded by 5 Dy atoms and 7 Ni atoms. The Ni2 atom (Wyckoff site 6c, site symmetry 3m) is surrounded by 3 Dy atoms and 9 Ni atoms. The Ni3 atom (Wyckoff site 3b, site symmetry 3m) is surrounded by 6 Dy atoms and 6 Ni atoms.

The interatomic distances in DyNi₃ are similar than those in Di₂Ni₇ (Levytskyy et al., 2012).

Experimental

The sample was prepared of the powdered commercially available pure elements: sublimed bulk pieces of dysprosium metal with a claimed purity of 99.99 at.% (Alfa Aesar, Johnson Matthey) and electrolytic nickel (99.99% pure) piece (Aldrich). A mixture of the powders was compacted in stainless steel dies. The pellet was arc-melted under an argon atmosphere on a water-cooled copper hearth. The alloy button (~1 g) was turned over and remolten three times to improve homogeneity. Subsequently, the sample was annealed in an evacuated silica tube under an argon atmosphere for four weeks at 1070 K. Shiny grey irregular-shaped crystals were isolated mechanically with a help of microscope by crushing the sample.