research papers
Crystal, electronic structure and hydrogenation properties of the Mg5.57Ni16Ge7.43 cluster phase with a new type of polyhedron
aDepartment of Inorganic Chemistry, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv, Ukraine, and bInstitute of Chemistry, Jan Dlugosz University, al. Armii Krajowej 13/15, Czestochowa 42200, Poland
*Correspondence e-mail: vpavlyuk2002@yahoo.com
The ternary germanide Mg5.57Ni16Ge7.43 (cubic, Fmm, cF116) belongs to the structural family based on the Th6Mn23-type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three-core-shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three-core-shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2.
Keywords: crystal structure; electronic structure; clusters; convex polyhedra; intermetallics; hydride; ternary; germanide; hydrogenation.
CCDC reference: 2347669
1. Introduction
Magnesium alloys and intermetallics, in addition to their unique mechanical properties, show great potential for use in various types of energy storage systems. These are in particular as hydrogen sorption materials for storage systems and metal hydride batteries (Edalati et al., 2018; Ouyang et al., 2020; Hitam et al., 2021). Binary alloys of magnesium with transition metals, such as Fe, Co, Ni, Zn and others, as well as ternary alloys with the additional involvement of p-elements, such as Al, Ga, Si, Ge, Sn, rare earth metals and others, have attracted special attention (Kalisvaart et al., 2010; Zhang et al., 2011; Pavlyuk et al., 2012, 2022a; Shtender et al., 2015). Due to the complexities of the synthesis of magnesium alloys and the complex nature of the physicochemical interaction of magnesium with other elements, ternary metallic systems are still not sufficiently studied. For example, study of the ternary Mg–Ni–Ge system began more than 60 years ago when the first results of analyzing the structures of MgNi1.6Ge0.4 and Mg6Ni16Ge7 by the powder Debye–Scherrer method were reported (Teslyuk & Markiv, 1962). MgNi1.6Ge0.4 (cubic, Fdm, a = 6.911 Å) belongs to the cubic Laves phase with the MgCu2 structure type. For Mg6Ni16Ge7 (cubic, Fmm, a = 11.532 Å), the Mg6Cu16Si7 structure type was proposed. Buchholz & Schuster (1981) described the of MgNi6Ge6 (hexagonal, P6/mmm, a = 5.067 and c = 3.860 Å) with the YCo6Ge6-type. The equiatomic MgNiGe phase (orthorhombic, Pnma, a = 6.4742, b = 4.0716 and c = 6.9426 Å) belongs to the TiNiSi-type (Hlukhyy et al., 2013). The Mg-rich compound Mg3Ni2Ge (cubic, Fdm, a = 11.521 Å) crystallizes in the Mn3Ni2Si-type (Gennari et al., 2003). Subsequently, the crystal structures of the two Laves phases Mg2Ni3Ge (Rm, a = 5.0300 and c = 11.330 Å) and MgNi2–xGex (x = 0.5, P63/mcm, a = 8.6946 and c = 7.8127 Å) were investigated using single-crystal X-ray diffraction methods (Siggelkow et al., 2017).
During our investigation of Ni-rich alloys of the ternary Mg–Ni–Ge system, we obtained a good-quality single crystal of the Mg5.57Ni16Ge7.43 ternary phase and report its here.
2. Experimental
2.1. Synthesis and crystallization
The target Mg20Ni55Ge25 species was prepared from the following reactants: magnesium, nickel and germanium (purity of elements is more than 99.99 wt%). Appropriate amounts of Mg, Ni and Ge pure elements were mixed according to the aimed-for stoichiometry of the product and filled into a tantalum crucible in a using a purified argon atmosphere. The Ta crucible was sealed by arc welding under a dry argon atmosphere. The reaction between the elements was carried out in an induction furnace at 1100 °C. After 20 min, the samples were cooled rapidly to room temperature by removing the crucibles from the furnace. The Ta container was placed in an evacuated quartz vial and thermally annealed to obtain good-quality single crystals suitable for This heating process was carried out at a rate of 5 °C min−1 to T = 800 °C in a resistance furnace and held at this temperature for 15–20 min with a thermal cycle controller. The sample was then cooled slowly (0.1 °C min−1) to 400 °C and the furnace was switched off. After cooling to room temperature, the sample could be separated from the tantalum container. The alloy is stable in air and includes single crystals, which exhibit metallic luster and could be isolated by mechanical fragmentation.
2.2. Refinement
The structure was solved by
after an analytical absorption correction.The Mg atom in the 24e site showed a displacement parameter that was different from the others, i.e. the Ni and Ge atoms.
Several important factors indicate that the 24e position is occupied mainly by Mg atoms with a small fraction of germanium (a statistical mixture of Mg/Ge). First, the title compound is isostructural with the Mg6Cu16Si7 structure type, where the 24e site is also occupied by Mg atoms. Second, analysis of the interatomic distances indicates that they are typical of the largest atom in this structure, which is magnesium. Thirdly, Fourier difference electron-density maps show the electron density to be associated with the Mg atom. During the first cycles of of the Mg atom in the 24e site, we noticed that, in addition to magnesium, there is also a small proportion of the heavier Ge or Ni atom in this site. The best results are for the Mg/Ge statistical mixture. The refined composition of the compound from single-crystal data correlates well with the energy-dispersive (EDS) analysis.
Crystal data, data collection and structure .
details are summarized in Table 13. Results and discussion
As part of a systematic study of Mg–Ni–Ge alloys, the ternary Mg5.57Ni16Ge7.43 phase was detected in the Ni-rich region. A small irregularly shaped single crystal was selected from the annealed sample by mechanical fragmentation. Intensity data were measured at room temperature on an Oxford Diffraction Xcalibur3 automatic diffractometer with a CCD detector (Mo Kα radiation, graphite monochromator, ω scan).
The title compound crystallizes in a cubic Mg6Cu16Si7 structure type (Nagorsen & Witte, 1953), which is an ordered of the Th6Mn23-type (Florio et al., 1952). The and coordination polyhedra of the crystallographically distinct atoms are shown in Fig. 1. The Mg/Ge atom (site symmetry 4m.m) is surrounded by 16 adjacent atoms, which form a pseudo-Frank–Kasper [(Mg/Ge)Ni8(Mg/Ge)4Ge4] polyhedron. The coordination polyhedra of the Ni1 and Ni2 atoms (.3m symmetry) are icosahedral [Ni1Ge3Ni6(Mg/Ge)3] and pseudo-Frank–Kasper polyhedral (CN = 13) [Ni2Ge4Ni6(Mg/Ge)3], respectively. At (0,0,0), there is a Ge1 atom surrounded by eight Ni atoms, which occupy the vertices of an [Ni8] cube, and also by six Mg/Ge atoms, which are at the vertices of an [(Mg/Ge)6] octahedron. The eight Ni atoms and six Mg/Ge atoms which surround the Ge1 atom form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with CN = 14. For the Ge2 atom, the polyhedron is a 14-vertex [Ge2Ni8(Mg/Ge)6] rhombododecahedron. In addition to octahedra filled by germanium, there are also empty [(Mg/Ge)6] octahedra, the arrangement of which in the is shown in Fig. 2. Ni atoms form a three-dimensional network in which [Ni8] cubes are visible, the vertices of which are joined by eight [Ni4] tetrahedra, which are also connected to other tetrahedra by one face and three edges, as shown in Fig. 3(a). Instead, the Mg and Ge atoms along the z axis form two types of 3- and 4-ring networks, namely, flat at z = 0 and [Fig. 3(b)], and slightly corrugated at z = and [Fig. 3(c)].
The ternary germanide Mg5.57Ni16Ge7.43 can also be described as three-core-shell clusters of [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] (see Fig. 4). The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within a [Ni32(Mg/Ge)24] pentacontatetrahedron. The [Ni32(Mg/Ge)24] polyhedron has vertices V = 56, faces F = 54 and edges E = 108. The Euler characteristic (χ) was classically defined for the surfaces of polyhedra, according to the formula (Richeson, 2012):
where V, E and F are, respectively, the numbers of vertices (corners), edges and faces in the given polyhedron. For the title structure, the [Ni32(Mg/Ge)24] polyhedron has V = 56, F = 54 and E = 108, which gives a Euler characteristic χ of 2; therefore, [Ni32(Mg/Ge)24] is a new type of convex polyhedron, namely, a pentacontatetrahedron, with the vertex configuration: 24 (3252), 24 (3452) and 8 (53). The pentacontatetrahedron is a new representative of Pavlyuk's group of polyhedra based on pentagonal, tetragonal and trigonal faces. In the pentacontatetrahedron are 24 pentagonal, six tetragonal and 24 trigonal faces (Fig. 5). In the title compound, the pentacontatetrahedra exhibits close packing in the (Fig. 6). Earlier, we described the structure of the cluster phase MgMn4Ga18 (Pavlyuk et al., 2022b), for which we discovered a pentacontaoctahedron with V = 40, F = 58 and E = 96, and also a convex polyhedron (χ = 2). We also described previously the formation of clusters in magnesium-containing intermetallics using the example of the quaternary phase Li20Mg6Cu13Al42 with a 60-atom truncated icosahedron (Pavlyuk et al., 2019) and new cubic cluster phases in the Mg–Ni–Ga system (Pavlyuk et al., 2020).
The electronic structure calculations were performed for the ordered structure Mg6Ni16Ge7 (the 24e site is fully occupied by Mg) using the tight-binding linear muffin-tin orbital (TB–LMTO) method with the atomic spheres approximation (ASA) in the TB–LMTO–ASA program (Version 4.7; Andersen, 1975; Andersen et al., 1984, 1986). Electronic energies were calculated using density functional theory (DFT) based on the local-density approximation (LDA) for the exchange-correlation functional as parameterized by von Barth & Hedin (1972). The electronic structure calculations were carried out using the non-spin-polarized approach with a dense k-point mesh in the irreducible of the crystallographic (48 irreducible k-points from 512 for NKABC = 8 × 8 × 8). From the calculations, a mapping of the electrons in real space was obtained using the electron localization function (ELF) (Becke & Edgecombe, 1990). Visualization of the electronic structure calculation data was achieved using wxDragon (Eck, 2012). The ELF is a simple measure of electron localization in atomic and molecular systems (Becke & Edgecombe, 1990).
If we consider the distribution of the ELF, two types of layers of atoms can be distinguished in the title structure [Figs. 7(a) and 7(b)] which are alternately packed along the z axis [Fig. 7(c)]. Layers of atoms at z = 0, , , [Figs. 7(a) and 7(c)] consist exclusively of Mg and Ge atoms. The ELF has the highest values (0.709 eV) around the Ge atoms, which is consistent with its higher [Figs. 7(a) and 7(d)]. Slightly corrugated layers of atoms at approximately z = , , and [Figs. 7(a) and 7(c)] consist exclusively of Ni atoms. The entire space of this layer has an average value of the distribution of the ELF function of 0.350 eV (indicated in green), which corresponds to delocalized electrons, which are typical for the metallic type of bonding between atoms. The dominance of the metallic bond is also reflected in the (DOS) at the the partial and total DOS are shown in Fig. 8.
The prepared Mg5.57Ni16Ge7.43 sample was hydrogenated by hydrogen gas at a pressure up to 12 bar and a temperature of 573 K. The PCT (pressure, composition and temperature) isotherms for the hydrogenation and dehydrogenation processes are presented in Fig. 9. At this condition, Mg5.57Ni16Ge7.43 absorbs up to 0.7 wt% H2. Crystallographic analysis of the structure made it possible to determine the geometrically acceptable coordinates of the sites that can be occupied by hydrogen, namely, 4b (, , ) and 48h (, , 0). These coordinates are the centres of the octahedral voids. In the 4b site, there is an [(Mg/Ge)6] octahedron, and in the 48h site, there is an octahedron of composition [(Mg/Ge)2Ni2Ge2], which is slightly deformed. In the case of full occupation of these sites with hydrogen, the hydrogen capacity reached 0.81 wt% H2. A slight difference in the hydrogen content in hydride from experimental data and that calculated from geometric considerations indicates that these positions are partially occupied by H atoms (approximately 86%).
The bulk alloy from which the single crystal was selected was examined by ). The EDS data from three selected spots give the average composition (in at%) of Mg19.3 (3)Ni55.2 (2)Ge25.5 (1) that correlates well with the PXRD data (Mg19.21Ni55.17Ge25.62).
(SEM), energy dispersive (EDS) and powder X-ray diffraction (PXRD). A scanning electron microscope (TESCAN Vega3 LMU) equipped with an Oxford Instruments energy-dispersive X-ray analyzer (Aztec ONE system) was used to determine the chemical composition of the alloy (Fig. 10The PXRD analysis of the sample before and after hydrogenation was carried out using a Rigaku Mini Flex D-600 powder diffractometer with Cu Kα radiation. As shown in Fig. 11, the structure of the intermetallic is preserved, and the shift of reflexes for the pattern after hydrogenation indicates an increase of the unit-cell dimension of the from a = 11.5036 (6) Å to a = 11.5753 (6) Å during the incorporation of hydrogen into the structural voids.
Supporting information
CCDC reference: 2347669
https://doi.org/10.1107/S2053229624003140/yp3234sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2053229624003140/yp3234Isup2.hkl
Mg5.57Ni16Ge7.43 | Mo Kα radiation, λ = 0.71073 Å |
Mr = 6454.98 | Cell parameters from 131 reflections |
Cubic, Fm3m | θ = 3.1–28.3° |
a = 11.5036 (6) Å | µ = 33.85 mm−1 |
V = 1522.3 (2) Å3 | T = 293 K |
Z = 1 | Prism, metallic light grey |
F(000) = 3010.1 | 0.06 × 0.05 × 0.03 mm |
Dx = 7.041 Mg m−3 |
Oxford Diffraction Xcalibur3 CCD diffractometer | 120 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.074 |
ω scans | θmax = 28.3°, θmin = 3.1° |
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008) | h = −15→15 |
Tmin = 0.470, Tmax = 0.683 | k = −15→15 |
12619 measured reflections | l = −15→15 |
131 independent reflections |
Refinement on F2 | 14 parameters |
Least-squares matrix: full | 0 restraints |
R[F2 > 2σ(F2)] = 0.013 | w = 1/[σ2(Fo2) + 35.3811P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.028 | (Δ/σ)max < 0.001 |
S = 1.25 | Δρmax = 0.63 e Å−3 |
131 reflections | Δρmin = −0.63 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ge1 | 0.0000 | 0.0000 | 0.0000 | 0.0040 (4) | |
Ge2 | 0.0000 | 0.2500 | 0.2500 | 0.00442 (18) | |
Ni1 | 0.33129 (4) | 0.33129 (4) | 0.33129 (4) | 0.00491 (19) | |
Ni2 | 0.11860 (4) | 0.11860 (4) | 0.11860 (4) | 0.00509 (19) | |
Mg | 0.2959 (2) | 0.0000 | 0.0000 | 0.0048 (4) | 0.929 (4) |
Ge | 0.2959 (2) | 0.0000 | 0.0000 | 0.0048 (4) | 0.071 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ge1 | 0.0040 (4) | 0.0040 (4) | 0.0040 (4) | 0.000 | 0.000 | 0.000 |
Ge2 | 0.0039 (4) | 0.0047 (2) | 0.0047 (2) | 0.000 | 0.000 | 0.0002 (3) |
Ni1 | 0.00491 (19) | 0.00491 (19) | 0.00491 (19) | 0.00057 (18) | 0.00057 (18) | 0.00057 (18) |
Ni2 | 0.00509 (19) | 0.00509 (19) | 0.00509 (19) | −0.00015 (18) | −0.00015 (18) | −0.00015 (18) |
Mg | 0.0073 (10) | 0.0035 (6) | 0.0035 (6) | 0.000 | 0.000 | 0.000 |
Ge | 0.0073 (10) | 0.0035 (6) | 0.0035 (6) | 0.000 | 0.000 | 0.000 |
Ge1—Ni2 | 2.3631 (8) | Ni1—Ni1x | 2.6450 (14) |
Ge1—Ni2i | 2.3632 (8) | Ni1—Ni1xii | 2.6450 (14) |
Ge1—Ni2ii | 2.3632 (8) | Ni1—Gexx | 2.7747 (7) |
Ge1—Ni2iii | 2.3632 (8) | Ni1—Mgxxi | 2.7747 (7) |
Ge1—Ni2iv | 2.3632 (8) | Ni1—Mgxxii | 2.7747 (7) |
Ge1—Ni2v | 2.3632 (8) | Ni2—Ge2xvii | 2.5359 (3) |
Ge1—Ni2vi | 2.3632 (8) | Ni2—Ge2xv | 2.5359 (3) |
Ge1—Ni2vii | 2.3632 (8) | Ni2—Ni1ix | 2.5789 (7) |
Ge2—Ni1viii | 2.3485 (1) | Ni2—Ni1xii | 2.5789 (7) |
Ge2—Ni1ix | 2.3485 (1) | Ni2—Ni1x | 2.5789 (7) |
Ge2—Ni1x | 2.3485 (1) | Ni2—Ni2ii | 2.7288 (9) |
Ge2—Ni1xi | 2.3485 (1) | Ni2—Ni2vi | 2.7288 (9) |
Ge2—Ni2ii | 2.5359 (3) | Ni2—Ni2iv | 2.7288 (9) |
Ge2—Ni2xii | 2.5359 (3) | Ni2—Gexvii | 2.8075 (17) |
Ge2—Ni2xiii | 2.5359 (3) | Ni2—Gexv | 2.8075 (17) |
Ge2—Ni2 | 2.5359 (3) | Mg—Ni1xii | 2.7747 (7) |
Ge2—Gexiv | 2.9239 (4) | Mg—Ni1xxiii | 2.7747 (7) |
Ge2—Mgxv | 2.9239 (4) | Mg—Ni1xxiv | 2.7747 (7) |
Ge2—Mgxvi | 2.9239 (4) | Mg—Ni1xxv | 2.7747 (7) |
Ge2—Mgxvii | 2.9239 (4) | Mg—Ni2vii | 2.8075 (17) |
Ni1—Ge2xviii | 2.3485 (1) | Mg—Ni2vi | 2.8075 (17) |
Ni1—Ge2x | 2.3485 (1) | Mg—Ni2iv | 2.8075 (17) |
Ni1—Ge2xix | 2.3485 (1) | Mg—Ge2xxvi | 2.9239 (4) |
Ni1—Ni2x | 2.5788 (7) | Mg—Ge2xxvii | 2.9239 (4) |
Ni1—Ni2xii | 2.5788 (7) | Mg—Ge2xv | 2.9239 (4) |
Ni1—Ni2ix | 2.5788 (7) | Mg—Ge2xvii | 2.9239 (4) |
Ni1—Ni1ix | 2.6450 (14) | ||
Ni2—Ge1—Ni2i | 180.00 (4) | Ni1x—Ni1—Mgxxi | 113.00 (4) |
Ni2—Ge1—Ni2ii | 70.5 | Ni1xii—Ni1—Mgxxi | 171.56 (5) |
Ni2i—Ge1—Ni2ii | 109.5 | Gexx—Ni1—Mgxxi | 73.5 |
Ni2—Ge1—Ni2iii | 109.5 | Ge2xviii—Ni1—Mgxxii | 69.03 (2) |
Ni2i—Ge1—Ni2iii | 70.5 | Ge2x—Ni1—Mgxxii | 69.03 (2) |
Ni2ii—Ge1—Ni2iii | 70.5 | Ge2xix—Ni1—Mgxxii | 132.71 (6) |
Ni2—Ge1—Ni2iv | 70.5 | Ni2x—Ni1—Mgxxii | 122.689 (18) |
Ni2i—Ge1—Ni2iv | 109.5 | Ni2xii—Ni1—Mgxxii | 122.689 (18) |
Ni2ii—Ge1—Ni2iv | 109.5 | Ni2ix—Ni1—Mgxxii | 63.13 (5) |
Ni2iii—Ge1—Ni2iv | 180.00 (6) | Ni1ix—Ni1—Mgxxii | 171.56 (5) |
Ni2—Ge1—Ni2v | 109.5 | Ni1x—Ni1—Mgxxii | 113.00 (4) |
Ni2i—Ge1—Ni2v | 70.529 (1) | Ni1xii—Ni1—Mgxxii | 113.00 (4) |
Ni2ii—Ge1—Ni2v | 70.5 | Gexx—Ni1—Mgxxii | 73.5 |
Ni2iii—Ge1—Ni2v | 109.5 | Mgxxi—Ni1—Mgxxii | 73.51 (7) |
Ni2iv—Ge1—Ni2v | 70.5 | Ge1—Ni2—Ge2xvii | 112.187 (17) |
Ni2—Ge1—Ni2vi | 70.5 | Ge1—Ni2—Ge2 | 112.187 (17) |
Ni2i—Ge1—Ni2vi | 109.5 | Ge2xvii—Ni2—Ge2 | 106.624 (19) |
Ni2ii—Ge1—Ni2vi | 109.5 | Ge1—Ni2—Ge2xv | 112.187 (17) |
Ni2iii—Ge1—Ni2vi | 70.5 | Ge2xvii—Ni2—Ge2xv | 106.624 (19) |
Ni2iv—Ge1—Ni2vi | 109.5 | Ge2—Ni2—Ge2xv | 106.624 (19) |
Ni2v—Ge1—Ni2vi | 180.00 (6) | Ge1—Ni2—Ni1ix | 143.69 (2) |
Ni2—Ge1—Ni2vii | 109.5 | Ge2xvii—Ni2—Ni1ix | 54.658 (12) |
Ni2i—Ge1—Ni2vii | 70.5 | Ge2—Ni2—Ni1ix | 54.658 (12) |
Ni2ii—Ge1—Ni2vii | 180.00 (4) | Ge2xv—Ni2—Ni1ix | 104.12 (3) |
Ni2iii—Ge1—Ni2vii | 109.5 | Ge1—Ni2—Ni1xii | 143.69 (2) |
Ni2iv—Ge1—Ni2vii | 70.5 | Ge2xvii—Ni2—Ni1xii | 54.658 (12) |
Ni2v—Ge1—Ni2vii | 109.5 | Ge2—Ni2—Ni1xii | 104.12 (3) |
Ni2vi—Ge1—Ni2vii | 70.5 | Ge2xv—Ni2—Ni1xii | 54.658 (12) |
Ni1viii—Ge2—Ni1ix | 180.0 | Ni1ix—Ni2—Ni1xii | 61.70 (3) |
Ni1viii—Ge2—Ni1x | 111.46 (4) | Ge1—Ni2—Ni1x | 143.69 (2) |
Ni1ix—Ge2—Ni1x | 68.54 (4) | Ge2xvii—Ni2—Ni1x | 104.12 (3) |
Ni1viii—Ge2—Ni1xi | 68.54 (4) | Ge2—Ni2—Ni1x | 54.658 (12) |
Ni1ix—Ge2—Ni1xi | 111.46 (4) | Ge2xv—Ni2—Ni1x | 54.658 (12) |
Ni1x—Ge2—Ni1xi | 180.0 | Ni1ix—Ni2—Ni1x | 61.70 (3) |
Ni1viii—Ge2—Ni2ii | 63.601 (15) | Ni1xii—Ni2—Ni1x | 61.70 (3) |
Ni1ix—Ge2—Ni2ii | 116.399 (15) | Ge1—Ni2—Ni2ii | 54.7 |
Ni1x—Ge2—Ni2ii | 116.399 (15) | Ge2xvii—Ni2—Ni2ii | 126.587 (8) |
Ni1xi—Ge2—Ni2ii | 63.601 (15) | Ge2—Ni2—Ni2ii | 57.451 (17) |
Ni1viii—Ge2—Ni2xii | 116.399 (15) | Ge2xv—Ni2—Ni2ii | 126.587 (8) |
Ni1ix—Ge2—Ni2xii | 63.601 (15) | Ni1ix—Ni2—Ni2ii | 102.914 (14) |
Ni1x—Ge2—Ni2xii | 63.601 (15) | Ni1xii—Ni2—Ni2ii | 161.57 (2) |
Ni1xi—Ge2—Ni2xii | 116.399 (15) | Ni1x—Ni2—Ni2ii | 102.914 (14) |
Ni2ii—Ge2—Ni2xii | 180.00 (3) | Ge1—Ni2—Ni2vi | 54.7 |
Ni1viii—Ge2—Ni2xiii | 63.601 (15) | Ge2xvii—Ni2—Ni2vi | 126.587 (8) |
Ni1ix—Ge2—Ni2xiii | 116.399 (15) | Ge2—Ni2—Ni2vi | 126.587 (8) |
Ni1x—Ge2—Ni2xiii | 116.399 (15) | Ge2xv—Ni2—Ni2vi | 57.451 (17) |
Ni1xi—Ge2—Ni2xiii | 63.601 (15) | Ni1ix—Ni2—Ni2vi | 161.57 (2) |
Ni2ii—Ge2—Ni2xiii | 114.90 (3) | Ni1xii—Ni2—Ni2vi | 102.914 (14) |
Ni2xii—Ge2—Ni2xiii | 65.10 (3) | Ni1x—Ni2—Ni2vi | 102.914 (14) |
Ni1viii—Ge2—Ni2 | 116.398 (15) | Ni2ii—Ni2—Ni2vi | 90.0 |
Ni1ix—Ge2—Ni2 | 63.602 (15) | Ge1—Ni2—Ni2iv | 54.7 |
Ni1x—Ge2—Ni2 | 63.602 (15) | Ge2xvii—Ni2—Ni2iv | 57.451 (17) |
Ni1xi—Ge2—Ni2 | 116.398 (15) | Ge2—Ni2—Ni2iv | 126.587 (8) |
Ni2ii—Ge2—Ni2 | 65.10 (3) | Ge2xv—Ni2—Ni2iv | 126.587 (8) |
Ni2xii—Ge2—Ni2 | 114.90 (3) | Ni1ix—Ni2—Ni2iv | 102.914 (14) |
Ni2xiii—Ge2—Ni2 | 180.0 | Ni1xii—Ni2—Ni2iv | 102.914 (14) |
Ni1viii—Ge2—Gexiv | 117.61 (2) | Ni1x—Ni2—Ni2iv | 161.57 (2) |
Ni1ix—Ge2—Gexiv | 62.39 (2) | Ni2ii—Ni2—Ni2iv | 90.0 |
Ni1x—Ge2—Gexiv | 117.61 (2) | Ni2vi—Ni2—Ni2iv | 90.0 |
Ni1xi—Ge2—Gexiv | 62.39 (2) | Ge1—Ni2—Gexvii | 81.85 (4) |
Ni2ii—Ge2—Gexiv | 118.60 (4) | Ge2xvii—Ni2—Gexvii | 165.96 (5) |
Ni2xii—Ge2—Gexiv | 61.40 (4) | Ge2—Ni2—Gexvii | 66.123 (16) |
Ni2xiii—Ge2—Gexiv | 61.40 (4) | Ge2xv—Ni2—Gexvii | 66.123 (16) |
Ni2—Ge2—Gexiv | 118.60 (4) | Ni1ix—Ni2—Gexvii | 114.04 (3) |
Ni1viii—Ge2—Mgxv | 117.61 (2) | Ni1xii—Ni2—Gexvii | 114.04 (3) |
Ni1ix—Ge2—Mgxv | 62.39 (2) | Ni1x—Ni2—Gexvii | 61.84 (4) |
Ni1x—Ge2—Mgxv | 117.61 (2) | Ni2ii—Ni2—Gexvii | 60.92 (2) |
Ni1xi—Ge2—Mgxv | 62.39 (2) | Ni2vi—Ni2—Gexvii | 60.92 (2) |
Ni2ii—Ge2—Mgxv | 61.40 (4) | Ni2iv—Ni2—Gexvii | 136.59 (4) |
Ni2xii—Ge2—Mgxv | 118.60 (4) | Ge1—Ni2—Gexv | 81.85 (4) |
Ni2xiii—Ge2—Mgxv | 118.60 (4) | Ge2xvii—Ni2—Gexv | 66.123 (16) |
Ni2—Ge2—Mgxv | 61.40 (4) | Ge2—Ni2—Gexv | 66.123 (16) |
Gexiv—Ge2—Mgxv | 69.2 | Ge2xv—Ni2—Gexv | 165.96 (5) |
Ni1viii—Ge2—Mgxvi | 62.39 (2) | Ni1ix—Ni2—Gexv | 61.84 (4) |
Ni1ix—Ge2—Mgxvi | 117.61 (2) | Ni1xii—Ni2—Gexv | 114.04 (3) |
Ni1x—Ge2—Mgxvi | 62.39 (2) | Ni1x—Ni2—Gexv | 114.04 (3) |
Ni1xi—Ge2—Mgxvi | 117.61 (2) | Ni2ii—Ni2—Gexv | 60.92 (2) |
Ni2ii—Ge2—Mgxvi | 118.60 (4) | Ni2vi—Ni2—Gexv | 136.59 (4) |
Ni2xii—Ge2—Mgxvi | 61.40 (4) | Ni2iv—Ni2—Gexv | 60.92 (2) |
Ni2xiii—Ge2—Mgxvi | 61.40 (4) | Gexvii—Ni2—Gexv | 118.025 (17) |
Ni2—Ge2—Mgxvi | 118.60 (4) | Ni1xii—Mg—Ni1xxiii | 163.12 (10) |
Gexiv—Ge2—Mgxvi | 110.8 | Ni1xii—Mg—Ni1xxiv | 88.766 (14) |
Mgxv—Ge2—Mgxvi | 180.0 | Ni1xxiii—Mg—Ni1xxiv | 88.766 (14) |
Ni1viii—Ge2—Mgxvii | 62.39 (2) | Ni1xii—Mg—Ni1xxv | 88.766 (14) |
Ni1ix—Ge2—Mgxvii | 117.61 (2) | Ni1xxiii—Mg—Ni1xxv | 88.766 (14) |
Ni1x—Ge2—Mgxvii | 62.39 (2) | Ni1xxiv—Mg—Ni1xxv | 163.12 (10) |
Ni1xi—Ge2—Mgxvii | 117.61 (2) | Ni1xii—Mg—Ni2 | 55.03 (2) |
Ni2ii—Ge2—Mgxvii | 61.40 (4) | Ni1xxiii—Mg—Ni2 | 141.85 (8) |
Ni2xii—Ge2—Mgxvii | 118.60 (4) | Ni1xxiv—Mg—Ni2 | 96.12 (3) |
Ni2xiii—Ge2—Mgxvii | 118.60 (4) | Ni1xxv—Mg—Ni2 | 96.12 (3) |
Ni2—Ge2—Mgxvii | 61.40 (4) | Ni1xii—Mg—Ni2vii | 141.85 (8) |
Gexiv—Ge2—Mgxvii | 180.0 | Ni1xxiii—Mg—Ni2vii | 55.03 (2) |
Mgxv—Ge2—Mgxvii | 110.80 (9) | Ni1xxiv—Mg—Ni2vii | 96.12 (3) |
Mgxvi—Ge2—Mgxvii | 69.20 (9) | Ni1xxv—Mg—Ni2vii | 96.12 (3) |
Ge2xviii—Ni1—Ge2x | 119.970 (1) | Ni2—Mg—Ni2vii | 86.83 (7) |
Ge2xviii—Ni1—Ge2xix | 119.970 (1) | Ni1xii—Mg—Ni2vi | 96.12 (3) |
Ge2x—Ni1—Ge2xix | 119.970 (1) | Ni1xxiii—Mg—Ni2vi | 96.12 (3) |
Ge2xviii—Ni1—Ni2x | 164.15 (4) | Ni1xxiv—Mg—Ni2vi | 141.85 (8) |
Ge2x—Ni1—Ni2x | 61.740 (4) | Ni1xxv—Mg—Ni2vi | 55.03 (2) |
Ge2xix—Ni1—Ni2x | 61.740 (4) | Ni2—Mg—Ni2vi | 58.15 (4) |
Ge2xviii—Ni1—Ni2xii | 61.740 (4) | Ni2vii—Mg—Ni2vi | 58.15 (4) |
Ge2x—Ni1—Ni2xii | 164.15 (4) | Ni1xii—Mg—Ni2iv | 96.12 (3) |
Ge2xix—Ni1—Ni2xii | 61.740 (4) | Ni1xxiii—Mg—Ni2iv | 96.12 (3) |
Ni2x—Ni1—Ni2xii | 111.970 (18) | Ni1xxiv—Mg—Ni2iv | 55.03 (2) |
Ge2xviii—Ni1—Ni2ix | 61.740 (4) | Ni1xxv—Mg—Ni2iv | 141.85 (8) |
Ge2x—Ni1—Ni2ix | 61.740 (4) | Ni2—Mg—Ni2iv | 58.15 (4) |
Ge2xix—Ni1—Ni2ix | 164.15 (4) | Ni2vii—Mg—Ni2iv | 58.15 (4) |
Ni2x—Ni1—Ni2ix | 111.970 (18) | Ni2vi—Mg—Ni2iv | 86.83 (7) |
Ni2xii—Ni1—Ni2ix | 111.970 (18) | Ni1xii—Mg—Ge2xxvi | 135.598 (4) |
Ge2xviii—Ni1—Ni1ix | 107.624 (17) | Ni1xxiii—Mg—Ge2xxvi | 48.589 (5) |
Ge2x—Ni1—Ni1ix | 107.624 (17) | Ni1xxiv—Mg—Ge2xxvi | 48.589 (5) |
Ge2xix—Ni1—Ni1ix | 55.73 (2) | Ni1xxv—Mg—Ge2xxvi | 135.598 (4) |
Ni2x—Ni1—Ni1ix | 59.148 (17) | Ni2—Mg—Ge2xxvi | 110.29 (6) |
Ni2xii—Ni1—Ni1ix | 59.148 (17) | Ni2vii—Mg—Ge2xxvi | 52.47 (2) |
Ni2ix—Ni1—Ni1ix | 108.43 (2) | Ni2vi—Mg—Ge2xxvi | 110.29 (6) |
Ge2xviii—Ni1—Ni1x | 55.73 (2) | Ni2iv—Mg—Ge2xxvi | 52.47 (2) |
Ge2x—Ni1—Ni1x | 107.624 (17) | Ni1xii—Mg—Ge2xxvii | 135.598 (4) |
Ge2xix—Ni1—Ni1x | 107.624 (17) | Ni1xxiii—Mg—Ge2xxvii | 48.589 (5) |
Ni2x—Ni1—Ni1x | 108.43 (2) | Ni1xxiv—Mg—Ge2xxvii | 135.598 (4) |
Ni2xii—Ni1—Ni1x | 59.148 (17) | Ni1xxv—Mg—Ge2xxvii | 48.589 (5) |
Ni2ix—Ni1—Ni1x | 59.148 (17) | Ni2—Mg—Ge2xxvii | 110.29 (6) |
Ni1ix—Ni1—Ni1x | 60.0 | Ni2vii—Mg—Ge2xxvii | 52.47 (2) |
Ge2xviii—Ni1—Ni1xii | 107.624 (17) | Ni2vi—Mg—Ge2xxvii | 52.47 (2) |
Ge2x—Ni1—Ni1xii | 55.73 (2) | Ni2iv—Mg—Ge2xxvii | 110.29 (6) |
Ge2xix—Ni1—Ni1xii | 107.624 (17) | Ge2xxvi—Mg—Ge2xxvii | 88.132 (16) |
Ni2x—Ni1—Ni1xii | 59.148 (17) | Ni1xii—Mg—Ge2xv | 48.589 (5) |
Ni2xii—Ni1—Ni1xii | 108.43 (2) | Ni1xxiii—Mg—Ge2xv | 135.598 (4) |
Ni2ix—Ni1—Ni1xii | 59.148 (17) | Ni1xxiv—Mg—Ge2xv | 135.598 (4) |
Ni1ix—Ni1—Ni1xii | 60.0 | Ni1xxv—Mg—Ge2xv | 48.589 (5) |
Ni1x—Ni1—Ni1xii | 60.0 | Ni2—Mg—Ge2xv | 52.47 (2) |
Ge2xviii—Ni1—Gexx | 132.71 (6) | Ni2vii—Mg—Ge2xv | 110.29 (6) |
Ge2x—Ni1—Gexx | 69.03 (2) | Ni2vi—Mg—Ge2xv | 52.47 (2) |
Ge2xix—Ni1—Gexx | 69.03 (2) | Ni2iv—Mg—Ge2xv | 110.29 (6) |
Ni2x—Ni1—Gexx | 63.13 (5) | Ge2xxvi—Mg—Ge2xv | 159.20 (9) |
Ni2xii—Ni1—Gexx | 122.689 (18) | Ge2xxvii—Mg—Ge2xv | 88.132 (16) |
Ni2ix—Ni1—Gexx | 122.689 (18) | Ni1xii—Mg—Ge2xvii | 48.589 (5) |
Ni1ix—Ni1—Gexx | 113.00 (4) | Ni1xxiii—Mg—Ge2xvii | 135.598 (4) |
Ni1x—Ni1—Gexx | 171.56 (5) | Ni1xxiv—Mg—Ge2xvii | 48.589 (5) |
Ni1xii—Ni1—Gexx | 113.00 (4) | Ni1xxv—Mg—Ge2xvii | 135.598 (4) |
Ge2xviii—Ni1—Mgxxi | 69.03 (2) | Ni2—Mg—Ge2xvii | 52.47 (2) |
Ge2x—Ni1—Mgxxi | 132.71 (6) | Ni2vii—Mg—Ge2xvii | 110.29 (6) |
Ge2xix—Ni1—Mgxxi | 69.03 (2) | Ni2vi—Mg—Ge2xvii | 110.29 (6) |
Ni2x—Ni1—Mgxxi | 122.689 (18) | Ni2iv—Mg—Ge2xvii | 52.47 (2) |
Ni2xii—Ni1—Mgxxi | 63.13 (5) | Ge2xxvi—Mg—Ge2xvii | 88.132 (16) |
Ni2ix—Ni1—Mgxxi | 122.689 (18) | Ge2xxvii—Mg—Ge2xvii | 159.20 (9) |
Ni1ix—Ni1—Mgxxi | 113.00 (4) | Ge2xv—Mg—Ge2xvii | 88.132 (16) |
Symmetry codes: (i) −x, −y, −z; (ii) −x, y, z; (iii) −x, −y, z; (iv) x, y, −z; (v) −x, y, −z; (vi) x, −y, z; (vii) x, −y, −z; (viii) x−1/2, −y+1/2, z; (ix) −x+1/2, y, −z+1/2; (x) −x+1/2, −y+1/2, z; (xi) x−1/2, y, −z+1/2; (xii) x, −y+1/2, −z+1/2; (xiii) −x, −y+1/2, −z+1/2; (xiv) −y, −z+1/2, −x+1/2; (xv) z, x, y; (xvi) −z, −x+1/2, −y+1/2; (xvii) y, z, x; (xviii) −y+1/2, z, −x+1/2; (xix) z, −x+1/2, −y+1/2; (xx) y+1/2, z+1/2, x; (xxi) x, y+1/2, z+1/2; (xxii) z+1/2, x, y+1/2; (xxiii) x, y−1/2, z−1/2; (xxiv) x, −y+1/2, z−1/2; (xxv) x, y−1/2, −z+1/2; (xxvi) z, −x, −y; (xxvii) −y+1/2, z−1/2, −x. |
Funding information
Funding for this research was provided by: National Research Foundation of Ukraine (grant No. 2022.01/0064).
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