We report a successful synthesis of a high-purity intermetallic germanide Y2Pd1.25Ge2.75, crystallizing in the disordered variant of the AlB2-type structure. A single-phase sample was obtained via arc-melting by deliberately tuning the composition out of the ideal 2:1:3 ratio. Specific heat, electrical resistivity and magnetization mea-surements show that the compound is a weakly-coupled (lambda e-p = 0.58) type-II superconductor with a super-conducting transition at Tc = 2.72 K. Additional magnetization measurements conducted under pressure up to 0.55 GPa show suppression of Tc, at a rate of _ 0.17 K/GPa. Electronic structure calculations reveal the deep similarity between Y2Pd1.25Ge2.75 and other AlB2-type germanide superconductors, especially the ordered YGa2 phase.

Single crystals of completely ordered variant of the YNi3Al9 compound were grown by self-flux method with excess of aluminum. The crystal structure of the title compound was redetermined from single crystal X-ray diffraction data. The structure adopts ErNi3Al9 type, space group R32, parameters of the unit cell a = 7.2838(2) angstrom, c = 27.4004(8) angstrom. The growth of relatively large single crystals of the YNi3Al9 compound, having completely ordered structure, indicates possible existence of region on phase diagram, where the title compound is in equilibrium with liquid. Comparison with the results in the literature on the investigations of the same and related compounds shows trend towards formation of more ordered structures in flux grown samples and more disor-dered ones in arc melted samples.Physical properties of the title compound -electrical resistivity, magnetoresistance and heat capacity -were measured for the first time. It shows metallic-like behavior with very high values of magnetoresistance up to 420% at low temperatures without presence of magnetic elements. Therefore electronic structure calculations were carried out. The phonon heat capacity reveals major Debye and minor Einstein contributions at the inter-mediate temperatures, and total heat capacity approaches Dulong-Petit limit at high temperatures. The calculated Debye temperature from the whole temperature range theta D = 480(6) K is typical for aluminium-rich compounds. Corresponding Einstein temperature is theta E = 198(8) K. The estimations of electron-phonon coupling constant lambda = 0.092 show very weak coupling and absence of superconducting transition.

The composition and electrochemical properties of the electrode material based on Cu 5 O 2 (PO 4 ) 2 (own structure type, space group P -1, Pearson’s code aP 17) were studied by X-ray powder diffraction, scanning electron microscopy, energy dispersion and X-ray fluorescence spectroscopy. Electrochemical lithiation of the phase, which was used as cathode material, was carried out in the “Swagelok-cell”-type battery prototype. Sheet of Li-metal was used as anode material. The anode and cathode materials were separated to avoid contact between them. An electrolyte for batteries consisted of 1 M Li[PF 6 ] solution and ethylene carbonate and dimethyl carbonate (1:1 vol. ratio). Morphology of the sample surfaces was studied using scanning electron microscope TESCAN Vega3 LMU. Quantitative composition of the powders (before and after lithiation) was studied using Oxford Instruments energy dispersive X-ray analyser (Aztec ONE system). X-ray fluorescent spectroscopy (spectrometer ElvaX Pro) was used for investigation of the integral composition of electrode before and after electrochemical processes and showed the Cu/P ratio equal 2.52 before lithiation and 2.47 after lithiation. The structural analysis of the Cu 5 O 2 (PO 4 ) 2 and Li x Cu 5 O 2 (PO 4 ) 2 phases was carried out by X-ray powder diffraction using STOE STADI P diffractrometer (Cu K α 1 -radiation, λ = 1.54060 Å). The unit cell parameters increase because of the inclusion of lithium in the free channels of the structure: а = 5.20298(9)→5.20401(7) Å, b = 5.29851(9)→5.29991(8) Å, c = 7.60715(13)→7.60889(11) Å, α = 82.4944(10)→82.4931(8)°, β = 89.8368(11)→89.8309(8)°, γ = 68.2629(9)→68.2595(7)°, V = 192.897(6)→ 193.026(5) Å 3 . The polycrystalline Cu 5 O 2 (PO 4 ) 2 sample contains lamellar particles 0.2–0.4 μm thick and up to 5 μm in length. The surface of electrode adsorbs actively the components of electrolyte, resulting in the formation of block-like aggregates with 1–5 μm in size. The total composition of the electrode before and after electrochemical Li-intercalation is practically unchanged. Keywords: electrochemical synthesis, X-ray powder diffraction, cathode material, Li-ion batteries.

We synthesize nanocomposites based on magnesium-hydride by the method of mechanical ball milling of magnesium powders with additions of TiN and ZrN in hydrogen. It is shown that the outlined procedure of mechanochemical synthesis is characterized by a high hydrogen absorption rate. The catalytic activity of the TiN and ZrN additives in the processes of hydrogen desorption from MgH2 is analyzed. Their activation energies are computed according to the curves of thermal desorption of hydrogen in a vacuum for different heating rates: 135 kJ/mole H2 for a composite with ZrN additive (very close to the value for pure MgH2) and a much lower value (65 kJ/mole H2) for the composite with TiN. The synthesized nanocomposites of magnesium hydride with TiN and ZrN additives are tested as materials for the units generating hydrogen as a result of hydrolysis. It is shown that, in the presence of MgCl2 catalyst, the ZrN composite is characterized by a slightly higher degree of conversion than pure MgH2.

The structure of hydrogen sublattice of the Mg2NiH0.3 phase has been studied by computational methods to overcome some ambiguities of the experimental method. Seven types of possible hydrogen sites (marked as X1 to X7) were found. Models with occupation of X1 or X2+X3 sites were found in the literature. Further analysis of geometry and electronic density of the Mg2Ni compound revealed three additional types of voids X4-X6. Models having from 1 to 3 hydrogen atoms per unit cell were tested. The optimization of some of the models with occupied X2 and X5 sites led to shift of hydrogen atoms into the new type of voids X7. It was revealed that two the most energetically favorable ordered models have two types of tetrahedral sites occupied by hydrogen: X3 (H@Mg3Ni) and X7(H@Mg2Ni2). It was suggested that the real structure was a superposition of these models with either two X3 or both X3+X7 voids occupied. The developed structure is close to and has the advantage over one of the models mentioned in the literature, since the trigonal X2 site presented in the literature model is split here into two adjacent tetrahedral X7 sites.

The crystal structure of the high-temperature modification of the compound Li2Zn5 was determined using single-crystal X-ray diffraction data. It is the first representative of a new binary structure type with triclinic space group P1̅, where the parameters of the unit cell are a = 8.0073(3)Å, b = 11.5956(6)Å, c = 15.2956(5)Å, α = 96.39°, β = 101.92°, and γ = 108.13°, the formula sum is Li11.748Zn31.113, Z = 2, and CCDC deposit number is 1861780. The title compound has a pseudohexagonal motif, made of 7- and 17-atom Li-zigzag chains and continuous Zn-chains, with the the relative placement of these large aggregates violating hexagonal symmetry. The structure may be decomposed into fragments, related to the AlB2 structure type, and could be obtained from multiplication of the unit cell, multiple substitution of Li atoms by triangles of Zn, insertion of Zn atoms, and deformation. Most structures of Li-Zn compounds, except LiZn, are highly symmetric but disordered. The possible causes of lower symmetry of β-Li2Zn5 were analyzed using the results of DFT calculations. β-Li2Zn5 shows high polarity of bonds, and Li atoms donate part of the electron density to Zn atoms.

La5Zn2−xPb1 + x (x = 0.20–0.32), tetragonal, I4/mcm (no. 140), a = 8.1673(12) Å, c = 15.367(3) Å, V = 1025.1(3) Å3, Z = 4, Rgt(F) = 0.0261, wRref(F2) = 0.0441, T = 293 K.

Crystal structure of ternary TbZn x Sn 2-x compound (defective derivative of CeNiSi 2 structure type, space group Cmcm, a = 4.407(1) A, b = 16.308(3) A, c = 4.306(1) A for composition TbZn 0,2 Sn 1,8 ) was determined from single crystal diffraction data. The unit cell parameters (a = 4.4056(3) A, b = 16.300(1) A, c = 4.3070(3) A for composition TbZn 0,37(5) Sn 1,63(5) ) and homogeneity range of ternary TbZn x Sn 2-x (x = 0.2-0.37) compound at 600 о C were established using X-ray powder diffraction data. Key words: terbium, zinc, tin, crystal structure.

The ternary compound Tb 0.83 Zn 0.14 Sn 2.86 was observed for the first time.The X-ray single crystal method was used to determine the crystal structure.The new stannide crystallizes in a new structure type, which is a derivative of AuCu 3 (space group Pmm2, a = 4.332(3) Å, b = 4.427(3) Å, c = 5.479(4) Å).The structural relationship between Tb 0.83 Zn 0.14 Sn 2.86 and other structure types with small unit cells and close-packed structures is discussed.Structure type / Terbium / Zinc / Tin / Ternary compound

The binary phases Ti 5 M 3 , Ti 3 M and Zr 3 M (M = Sn, Sb) were studied for electrochemical lithiation, using powder X-ray diffraction, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX).The investigation showed that the morphology of the cathode and the anode surfaces undergo changes, and the grain size of the materials decreases.The phase analysis of the anode materials revealed that the Ti 5 Sn 3 (structure type Mn 5 Si 3 ) and Ti 3 Sn (structure type Mg 3 Cd) phases form solid solutions by insertion of Li atoms into the initial structure.The insertion is reversible.The phases Ti 5 Sb 3 (structure type Y 5 Bi 3 ), Ti 3 Sb, Zr 3 Sn (structure type Cr 3 Si), and Zr 3 Sb (structure type Ni 3 P) form solid solutions by substitution of Li for Sn or Sb atoms.Only the Zr 3 Sb phase showed weakly reversible substitution.Among the investigated compounds, the most suitable structure types for intercalation of lithium appeared to be the Mn 5 Si 3 -and Mg 3 Cd-types, where the Li atoms occupy octahedral voids.The intermetallic compounds containing tin showed better ability for electrochemical lithiation than the compounds containing antimony.This can be explained by the easier interaction of antimony and lithium with the formation of binary compounds. Intermetallic compound / Electrochemical lithiation / Li-ion battery

The title non-stoichiometric pentalanthanum zinc diplumbide, La5Zn1−xPb2+x (x ≃ 0.6), was prepared from the elements in an evacuated silica ampoule. It adopts the Nb5Sn2Si-type structure (space group I4/mcm, Pearson symbol tI32), a ternary ordered superstructure of the W5Si3 type. Among the four independent crystallographic positions, three are fully occupied by La (Wyckoff 16k), La (4b), and Pb (8h) and one is occupied by a statistical mixture [occupancy ratio 0.394 (12):0.606 (12)] of Zn and Pb (4a). The structure is constructed by face-sharing 10-vertex polyhedra around the unmixed Pb sites. These fragments enclose channels of trans-face-sharing tetragonal antiprisms occupied by the disordered Zn and Pb sites.

During the systematic investigation of the tin-rich side of the Tb-Sn binary system temperatures of non-variant transformations were established. The crystal structure of βTb3Sn7 was determined for the first time from single-crystal diffraction data. Parameters of the unit cell have been determined previously by Manfrinetti & Palenzona [(1993), J. Alloys Compd. 201, 43-47], but the structure was not solved until now. The compound belongs to a new structure type with space group Pmmm. The unit cell contains two split positions: Sn7 (Wyckoff 1a), Sn7A (Wyckoff 2q) and Sn8 (Wyckoff 1d), Sn8A (Wyckoff 2s). Structures of both α- and β-modifications of Tb3Sn7 can be described as close packing of the coordination polyhedra of Tb atoms. In turn these polyhedra can be constructed of fragments of simple AuCu3 and CsCl types.

The structure of lanthanum tetrazinc, LaZn(4), has been determined from single-crystal X-ray diffraction data for the first time, approximately 70 years after its discovery. The compound exhibits a new structure type in the space group Cmcm, with one La atom and two Zn atoms occupying sites with m2m symmetry, and one Zn atom occupying a site with 2.. symmetry. The structure is closely related to the BaAl(4), La(3)Al(11), BaNi(2)Si(2) and CaCu(5) structure types, which can be presented as close-packed arrangements of 18-vertex clusters, in this case LaZn(18). The kindred structure types contain related 18-vertex clusters around atoms of the rare earth or alkaline earth metal.

The new terbium (lithium zinc) distannide, TbLi(1-x)Zn(x)Sn(2) (x = 0.2) crystallizes in the ortho-rhom-bic CeNiSi(2) structure type with space group Cmcm and Pearson symbol oS16. Of the four independent 4c atom positions (m2m site symmetry), three are fully occupied by individual atoms (two by Sn and one by Tb atoms) and the fourth is occupied by Li and Zn atoms with a statistical distribution. The Tb coordination polyhedron is a 21-vertex pseudo-Frank-Kasper polyhedron. One Sn atom is enclosed in a tricapped trigonal prism, the second Sn atom is in a cubocta-hedron and the statistically distributed (Li,Zn) site is in a tetra-gonal anti-prism with one added atom. Electronic structure calculations were used for the elucidation of reasons for and the ability of mutual substitution of lithium and transition metals. Positive charge density was observed around the rare earth atom and the Li and Zn atoms, the negative charge density in the proximity of the Sn atoms.

AbstractThe crystal structure of the title compound is determined by single crystal XRD.

The title compound (lanthanum dodecazinc), LaZn12.37 (1), is confirmed to be a nonstoichiometric (zinc-deficient) modification of the NaZn13 structure type, in which one Zn atom (Wyckoff site 8b, site symmetry m (3) over bar) has a fractional site occupancy of 0.372 (11). The other Zn atom (96i, m) and the La atom (8a, 432) are fully occupied. The coordination polyhedra of the Zn atoms are distorted icosahedra, whereas the La atoms are surrounded by 24 Zn atoms, forming pseudo-Frank-Kasper polyhedra. Electronic structure calculations indicate that Zn-Zn bonding is much stronger than La-Zn bonding.

A single crystal of penta-lanthanum dizinc stannide, La(5)Zn(2)Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo(5)SiB(2) structure type, which is a ternary ordered variant of the Cr(5)B(3) structure type. The space is filled by bicapped tetra-gonal anti-prisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetra-gonal anti-prisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m); La2 (4/m..); Zn (m.2m); Sn (422).

The crystal structure of the already known binary title compound LaZn(5) (lanthanum penta-zinc) (space group P6/mmm, Pearson symbol hP6, CaCu(5) structure type) has been redetermined from single-crystal X-ray diffraction data. In contrast to previous determinations based on X-ray powder data [Nowotny (1942). Z. Metallkd.34, 247-253; de Negri et al. (2008). Inter-metallics, 16, 168-178], where unit-cell parameters and assignment of the structure type were reported, the present study reveals anisotropic displacement parameters for all atoms. The crystal structure consists of three crytallographically distinct atoms. The La atom (Wyckoff site 1a, site symmetry 6/mmm) is surrounded by 18 Zn atoms and two La atoms. The coordination polyhedron around one of the Zn atoms (Wyckoff site 2c, site symmetry -6m2) is an icosa-hedron made up from three La and nine Zn atoms. The other Zn atom (Wyckoff site 3g, site symmetry mmm) is surrounded by four La and eight Zn atoms. Bonding between atoms is explored by means of the TB-LMTO-ASA (tight-binding linear muffin-tin orbital atomic spheres approximation) program package. The positive charge density is localized around La atoms, and the negative charge density is around Zn atoms, with weak covalent bonding between the latter.