ZrNiAl Type Research Articles

DyIrSn and the Lu3Co2In4-type stannides Sm3Rh2Sn4 and RE 3Ir2Sn4 (RE = Y, Sm, Gd–Tm, Lu)

Abstract The Lu3Co2In4-type stannides RE 3Ir2Sn4 (RE = Y, Sm, Gd–Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing sequences in sealed silica ampoules. For a more comprehensive phase analytical study, the isotypic stannide Sm3Rh2Sn4 and the ZrNiAl-type stannides DyIrSn and LT-YIrSn were also obtained. The polycrystalline samples were characterized through their X-ray powder patterns. The structures of DyIrSn and Gd3Ir2.63(2)Sn3.37(2) (ZrNiAl type, space group P6‾2m), Sm3Ir2.52(2)Sn3.48(1), Gd3Ir2.49(1)Sn3.51(1) and Tm3Ir2.20(3)Sn3.80(3) (Lu3Co2In4 type, space group P6‾) were refined from single-crystal X-ray diffractometer data, revealing residual Ir/Sn disorder in the low-symmetry variants. The RE 3Ir2Sn4 stannides are derived from the equiatomic stannides REIrSn (≍RE 3Rh3Sn3) by partial Ir/Sn substitution. The symmetry reduction from space group P6‾2m to P6‾ is forced by the Ir/Sn ordering within the RE 6 trigonal prisms. The new Sn2 position shows the rare motif of a trigonal planar tin coordination with 289 pm Sn2–Sn1 distances (data for Gd3Ir2.49(1)Sn3.51(1)). 119Sn Mössbauer spectra confirm the two crystallographically independent tin sites in Tm3Ir2Sn4 and the structural disorder in Gd3Ir2Sn4.

The crystal structures and magnetic properties of YbMg0.75In1.25 and Yb6Mg6.41In5.59

Abstract The quasi-binary system YbMg2-YbIn2 was studied around the equiatomic composition. In contrast to the ordered rare earth (RE) phases REMgIn (ZrNiAl type), ytterbium forms phases with different structures and pronounced Mg/In mixing (M sites). The structures of YbMg0.75In1.25 (CaLiSn type, P3m1, a = 501.95(7), c = 1087.3(2) pm, wR2 = 0.0490, 790 F 2 values, 32 variables) and Yb6Mg6.41In5.59 (Yb6Ir5Ga7 type, P63/mcm, a = 1060.77(14), c = 970.27(16) pm, wR2 = 0.0484, 701 F 2 values, 26 variables) were refined from single-crystal X-ray diffractometer data. YbMg0.75In1.25 is an AlB2 superstructure with a tripling of the subcell. The magnesium and indium atoms form three differently puckered layers of M 6 hexagons. The Yb6Mg6.41In5.59 structure is derived from the hexagonal Laves phase YbMg2 (MgZn2 type, P63/mmc). A klassengleiche symmetry reduction leads to four crystallographically independent M sites for the rows of corner- and face-sharing tetrahedra which allow a composition close to the equiatomic one. The M–M distances in both structures cover the broad range from 289 to 331 pm, comparable to the sums of the covalent radii. Temperature dependent magnetic susceptibility studies of the polycrystalline YbMg0.75In1.25 and Yb12Mg13In11 samples indicate Pauli paramagnetism with room temperature values of 2.8(1) × 10−3 emu mol−1 (YbMg0.75In1.25) and 5.2(1) × 10−3 emu mol−1 (Yb12Mg13In11).

Ternary magnesium gallides – synthesis, crystal chemistry and properties of CaMgGa, SrMgGa, BaMgGa and YbMgGa

AbstractThe gallides CaMgGa, SrMgGa, BaMgGa and YbMgGa were synthesized from the elements in sealed tantalum ampoules in muffle furnaces. The phase purity of the samples was checked by powder X‐ray diffraction. CaMgGa and YbMgGa crystallize with the ZrNiAl type structure, space group P 2m, whereas SrMgGa and BaMgGa adopt an ordering variant of the Cu2Sb/PbFCl type, space group P4/nmm. The structures of SrMg0.884(7)Ga1.116(7) (a=459.23(9), c=792.43(12) pm, wR2=0.0371, 226 F2 values, 11 variables) and YbMgGa (a=774.55(7), c=411.95(4) pm, wR2=0.0329, 342 F2 values, 15 variables) were refined from single crystal X‐ray diffractometer data. Refinement of the occupancy parameters indicated a small degree of Mg/Ga mixing on the 2a site for the strontium compound. The [MgGa] substructures in both compounds are composed of condensed Mg@Ga4 tetrahedra with 4×287 pm Mg−Ga in SrMg0.884Ga1.116 vs 2×282 and 2×296 pm in YbMgGa. The SrMgGa structure has a stacking of layers of edge‐sharing Mg@Ga4 and Sr4 tetrahedra. Electronic structure calculations indicate a net charge transfer from strontium and magnesium to gallium. YbMgGa completes the series of REMgGa gallides. Temperature dependent magnetic susceptibility studies reveal weak Pauli paramagnetism, confirming divalent ytterbium.

Structure and properties of phases from solid solutions YTIn1−x Al x (T = Ni and Cu)

Abstract YNiIn and YCuIn form complete solid solutions YNiIn1−x Al x and YCuIn1−x Al x , which were characterized on the basis of X-ray powder diffraction. The ZrNiAl type crystal structures (space groups P 6 ‾ 2 m $P\overline{6}2m$ ) of YNiAl (a = 0.70386(9), c = 0.38327(4) nm, wR 2 = 0.0424), YNiIn0.77Al0.23 (a = 0.73895(9), c = 0.37707(4) nm, wR 2 = 0.0498) and YCuIn0.63Al0.37 (a = 0.73404(7), c = 0.39045(4) nm, wR 2 = 0.0314) were refined from the single crystal X-ray diffraction data. Exemplarily the electronic structure of YNiAl was studied, manifesting substantial Ni–Al bonding within the three-dimensional [NiAl] substructure. Comparison of YNiAl with isotypic YNiIn shows stronger Ni–Al bonding as compared to Ni–In. Magnetic susceptibility measurements of YNiIn1−x Al x (x = 0.1, 0.2, 0.7 and 0.9), YNiIn and YNiAl in the temperature range 3–300 K indicated Pauli paramagnetic behaviour with molar magnetic susceptibility of about 0.15–0.22 × 10−3 emu/mol.

The solid solutions TbCuIn1–x M x (M = Al, Ga)

Abstract The complete solid solutions TbCuIn1–x M x (M = Al, Ga) were studied by powder X-ray diffraction and scanning electron microscopy for samples equilibrated at T = 873 K. The influence of In substitution by Al or Ga, the solubility ranges and the changes of unit cell parameters have been determined: TbCuIn1.0–0Al0–1.0 (ZrNiAl type, space group P 6 ‾ 2 $\overline{6}2$ m, a = 0.7457(1)–0.7035(1), c = 0.3958(1)–0.4044(1) nm, V = 0.1906–0.1733 nm3); TbCuIn1–0.8Ga0–0.2 (ZrNiAl type, a = 0.74569(5)–0.73882(13), с = 0.39582(3)–0.39663(14) nm, V = 0.1906–0.1875 nm3); TbCuIn0.3–0Ga0.7–1.0 (KHg2 type, Imma, а = 0.43943(9)–0.43750(5), b = 0.70833(12)–0.70537(6), с = 0.74866(12)–0.74525(7) nm, V = 0.2330–0.2300 nm3). The crystal structure of TbCuIn0.42(1)Al0.58(1) was refined from single-crystal X-ray diffractometer data: ZrNiAl type, P 6 ‾ 2 $\overline{6}2$ m, a = 0.71633(6), c = 0.40785(3) nm, wR2 = 0.0379, 291 F 2 values and 16 variables. The basic crystal chemical features are discussed.

Scandium–copper–indides deriving from the ZrNiAl and MnCu2Al type structures

Abstract Phase analytical studies in the Sc–Cu–In system led to samples of the solid solutions ScCu1–x–y In1+x and ScCu2–x In which were studied by X-ray powder diffraction. At room temperature the compounds ScCu1–x–y In1+x crystallize with the ZrNiAl type, space group P 6 ‾ $\overline{6}$ 2m. Exemplarily, the structure of ScCu0.76In1.17 was refined from single crystal X-ray diffractometer data, revealing strong anisotropic displacements for the scandium atoms and a mixed occupied Cu/In site. Superstructure formation is observed at low temperatures. The ScCu0.78In1.14 and ScCu0.76In1.16 structures were refined from diffraction data recorded at 90 K. Both compounds adopt the HfRhSn type, space group P 6 ‾ $\overline{6}$ 2c, a klassengleiche subgroup of index 2; doubling of the subcell c axis. The Cu/In filled trigonal Sc6 prisms are strongly distorted in the superstructure, resulting from pairwise dislocation of the Cu/In atoms from ideal positions within an equidistant chain to shorter (311.0 pm) and longer (392.8 pm) Cu/In–Cu/In distances. Single crystal data of the Heusler phases ScCu1.95In and ScCu1.94In show small degrees of copper vacancies.

Gadolinium spin dilution in the solid solution Gd1–xYxAuMg – gradual decrease of the Néel temperature

AbstractThe intermetallic compounds GdAuMg and YAuMg form a continuous solid solution Gd1–xYxAuMg. Samples in x=0.1 steps were synthesized from the elements in sealed tantalum ampoules in an induction furnace. Phase purity of the samples was checked by powder X‐ray diffraction. The structures of two members of the solid solution were refined from single crystal X‐ray diffractometer data: ZrNiAl type, P 2m, a=756.16(6), c=413.06(4) pm, wR2=0.0402, 328 F2 values, 16 variables for Gd0.80(2)Y0.20(2)AuMg and a=754.82(7), c=411.24(4) pm, wR2=0.0292, 325 F2 values, 16 variables for Gd0.37(1)Y0.63(1)AuMg. Temperature dependent magnetic susceptibility studies show a continuous decrease of the Néel temperature from TN=81.1(1) K (GdAuMg) to 3.5(1) K (Gd0.1Y0.9AuMg). With increasing x in Gd1–xYxAuMg the saturation magnetization increases, with a maximal value of 6.44(1) μB Gd atom−1 for Gd0.1Y0.9AuMg at 3 K. The dilution of the gadolinium substructure with yttrium pushes the magnetization isotherms close to Brillouin type behavior (free Gd3+).

Superstructure formation in the solid solution Sc3Pt3−xIn3 (x = 0–0.93)

Abstract The equiatomic indide ScPtIn (ZrNiAl type, space group P 6 ‾ $‾{6}$ 2m) shows an extended solid solution Sc3Pt3–xIn3. Several samples of the Sc3Pt3–xIn3 series were synthesized from the elements by arc-melting and subsequent annealing, or directly in a high frequency furnace. The lowest platinum content was observed for Sc3Pt2.072(3)In3. All samples were characterized by powder X-ray diffraction and their lattice parameters and several single crystals were studied on the basis of precise single crystal X-ray diffractometer data. The correct platinum occupancy parameters were refined from the diffraction data. Decreasing platinum content leads to decreasing a and c lattice parameters. Satellite reflections were observed for the Sc3Pt3–xIn3 crystals with x = 0.31–0.83. These satellite reflections could be described with a modulation vector ( 1 3 , 1 3 , γ ) $\left(\frac{1}{3},\frac{1}{3},\gamma \right)$ ( γ = 1 2 $\gamma =\frac{1}{2}$ c* for all crystals) and are compatible with trigonal symmetry. The interplay of platinum filled vs. empty In6 trigonal prisms is discussed for an approximant structure with space group P3m1.

YIrIn with ZrNiAl-type structure

Abstract The indide YIrIn was synthesized from the elements in a sealed tantalum ampoule in a high-frequency furnace. YIrIn adopts the ZrNiAl type. The crystal structure was refined from single-crystal X-ray diffractometer data: P6–2m, a = 750.63(6), c = 392.04(3) pm, wR = 0.0346, 308 F 2 values and 16 variables. Refinement of the occupancy parameters revealed a small degree of Ir/In mixing (0.912(9) Ir2/0.088(9) In1) on the 2d site. The YIrIn structure contains two crystallographically independent iridium sites, both with tri-capped trigonal prismatic coordination: Ir1@In6Y3 and Ir2@In3Y6.

Hydrogen influence in the UNiAl-UNiGa system: Structure and magnetism

Hydrogen absorption studies on UNiAl1-xGax were performed as part of our investigation of UTX compounds. The whole series crystallizes in the hexagonal structure of the ZrNiAl type (s.g. P-62m). The amount of hydrogen absorbed has a decreasing tendency with increasing Ga concentration. Studies of the temperature dependence of magnetic susceptibility indicate certain increase of the critical temperature of magnetic ordering in the hydrides but the increment becomes smaller with increasing Ga concentration as a result of smaller H absorption and concomitant changes in the crystal structure.

Phase equilibrium in the Gd-Ni-In system at 870 K

Abstract The isothermal section of the Gd-Ni-In system at T = 870 K was constructed by means of X-ray powder diffraction and EDX analyses. Thirteen ternary compounds, namely GdNi9In2 (YNi9In2 type), Gd1−1.22Ni4In1-0.78 (MgCu4Sn type), GdNiIn2 (MgCuAl2 type), Gd4Ni11In20 (U4Ni11Ga20 type), GdNi1.0-0.7In1.0-1.3 (ZrNiAl type), Gd2Ni2In (Mn2AlB2 type), Gd2Ni1.78In (Mo2FeB2 type), Gd11Ni4In9 (Nd11Pd4In9 type), Gd12Ni6In (Sm12Ni6In type), Gd6Ni2.39In0.61 (Ho6Co2Ga type), Gd14Ni3.29In2.71 (Lu14Co3In3 type), Gd3Ni0.05In0.95 (AuCu3 type) and ~Gd6Ni2In exist in the Gd-Ni-In system at this temperature. The substitution of Ni for In was observed for GdNi1.0-0.7In1.0-1.3 and of In for Gd for Gd1-1.22Ni4In1-0.78. Besides, Gd can enter the structure of NiIn (CoSn type) leading to a solid solution Gd0-0.14NiIn1-0.98.

Rare earth-copper-magnesium intermetallics: crystal structure of CeCuMg, magnetocaloric effect of GdCuMg and physical properties of the Laves phasesRECu4Mg (RE=Sm, Gd, Tb, Tm)

AbstractThe intermetallic magnesium compounds CeCuMg and GdCuMg as well as the ternary Laves phasesRECu4Mg (RE=Sm, Gd–Tm) were synthesized from the elements by different annealing sequences in high-frequency and muffle furnaces using niobium ampoules as crucibles. All samples were characterized through the lattice parameters using X-ray powder diffraction (Guinier technique). Two structures were refined from single-crystal X-ray diffractometer data:a=764.75(6),c=414.25(4) pm, space groupP6̅2m,wR2=0.0389, 338F2values, 15 parameters for CeCuMg (ZrNiAl type) anda=723.18(2) pm, space groupF4̅3m, wR2=0.0818, 91F2values, eight parameters for Gd1.06(3)Cu4Mg0.94(3)(MgCu4Sn type). The Laves phase shows a small homogeneity range (Gd/Mg mixing). An investigation of the magnetocaloric effect (MCE) of ferromagnetic GdCuMg (ZrNiAl type;TC=82 K) revealed a magnetic entropy change of ΔSM=6.5 J kg−1K−1and a relative cooling power of RCP=260 J kg−1for a field change from 0 to 70 kOe, classifying GdCuMg as a moderate magnetocaloric material for theT=80 K region. Of the Laves phasesRECu4Mg, SmCu4Mg shows van-Vleck paramagnetism above a Néel temperature of 10.8(5) K, whereas GdCu4Mg and TbCu4Mg undergo antiferromagnetic phase transitions at about 48 and 30 K, respectively. TmCu4Mg shows Curie-Weiss behavior in the entire temperature range. The electrical resistivity of SmCu4Mg and the specific heat capacity of GdCu4Mg were measured for further characterization.

Anisotropic lattice compression of α- and β-CePdZn

The lattice constants of ZrNiAl type α-CePdZn and TiNiSi type β-CePdZn were measured at high pressure up to 14GPa at room temperature using X-ray diffraction (XRD) and a diamond anvil cell. The pressure dependence of lattice constants and volume of α-CePdZn were found to be smooth without any discontinuity, and having a bulk modulus, B0, and its pressure derivative, B0′, of 67GPa and 5.1, respectively. On the other hand, the a and b axes as well as volume of β-CePdZn were found to show anomalous pressure dependence at around 8GPa. B0 and B0′ of β-CePdZn were 90GPa and 2.1, respectively. These results suggest that a crossover in the electronic states is induced by applying pressure to β-CePdZn. The origins of these anomalous behaviors are discussed in connection with crossover and change in the topology of Fermi surface.

Equiatomic indides REIrIn (RE=La, Pr, Nd, Er–Yb) – Crystal and electronic structure

Abstract The equiatomic rare earth iridium indides REIrIn (RE=La, Pr, Nd, Er–Yb) were synthesized by reaction of the elements in induction or muffle furnaces and were characterized through X-ray powder patterns. The structures of LaIr0.86In1.14, PrIr0.89In1.11, NdIr0.94In1.06, ErIrIn (all ZrNiAl type, P6̅2m), and YbIrIn (TiNiSi type, Pnma) were refined from single crystal X-ray diffractometer data. Refinements of the occupancy parameters revealed small degrees of solid solutions with indium substitution on the iridium sites. Chemical bonding analyses and electronic structure calculations indicate the dominance of metallic bonding in addition to partial ionic interactions between the cations and polyanions, as well as covalent contributions between the indium and iridium atoms.

Hydrogenation-induced cerium valence change in CeNiZn

Polycrystalline CeNiZn (ZrNiAl type, P6¯2m, a = 715.6 (4), c = 388.4 (2) pm) forms a new hydride CeNiZnH1.2(1) under hydrogen exposure (10 bar) at 423 K. The resulting hydride crystallizes in a hexagonal structure (P6/mmm) with the unit cell parameters a = 433.19 (2) and c = 424.37 (2) pm. Thus, hydrogen atom insertion yields a structural transition from a ZrNiAl- to an AlB2-type structure with a high volume cell expansion of +20.1%. The magnetic, thermal and transport properties of CeNiZnH1.2(1) were investigated. Susceptibility and specific heat measurements do not reveal magnetic order down to 1.8 K but most likely the presence of ferromagnetic correlations due to the proximity of a ferromagnetic order or a nonmagnetic atom disorder spin-glass state. Moreover, the cerium valence is modified from an intermediate to a trivalent state, a change that results from the decrease of the hybridization strength between conduction and Ce (4f) electrons upon hydrogenation. Transport measurements also evidence a deviation from the typical resistivity behavior of metallic systems. Several scenarios are conceived to explain this change, in particular weak localization effect, knowing that it rarely occurs upon hydrogenation of intermetallics.

GdCuMg with ZrNiAl-type structure – an 82.2 K ferromagnet

AbstractGdCuMg has been synthesized by induction-melting of the elements in a sealed niobium ampoule followed by annealing in a muffle furnace. The sample was studied by powder and single crystal X-ray diffraction: ZrNiAl type,P6̅2m(a=749.2(4),c=403.3(1) pm),wR2=0.0242, 315F2values and 15 variables. Temperature dependent magnetic susceptibility measurements have revealed an experimental magnetic moment of 8.54(1) μBper Gd atom. GdCuMg orders ferromagnetically belowTC=82.2(5) K and based on the magnetization isotherms it can be classified as a soft ferromagnet.

Equiatomic intermetallic compounds REPtMg (RE = Y, Eu, Tb-Tm, Lu) – Structure and magnetism

Eight new equiatomic REPtMg intermetallics with RE = Y, Eu, Tb-Tm, Lu were synthesized from the elements in sealed niobium ampoules (induction melting followed by different annealing sequences). All samples were characterized through X-ray powder patterns and the structures of YPtMg, EuPtMg, DyPtMg, HoPtMg and TmPtMg were refined from single crystal X-ray diffractometer data. The REPtMg phases crystallize with two different structure types. The representatives with RE = Y, Tb-Ho crystallize with the hexagonal ZrNiAl type, space group P6¯2m, while those with RE = Eu, Yb and Lu adopt the orthorhombic TiNiSi type, space group Pnma. ErPtMg and TmPtMg are dimorphic with a ZrNiAl type high and a TiNiSi type low-temperature modification. Temperature-dependent magnetic susceptibility measurements indicate Pauli paramagnetism for YPtMg and LuPtMg while EuPtMg, TbPtMg, DyPtMg and HoPtMg are Curie-Weiss paramagnets. Antiferromagnetic (TN = 12.6 K for EuPtMg) respectively ferromagnetic ordering (TC = 56.3 K for TbPtMg, 28.8 K for DyPtMg and 19.9 K for HoPtMg) occurs in the low-temperature regime. 151Eu Mössbauer spectra confirm divalent europium (δ = −8.03 mm s−1 at 78 K) in EuPtMg and show strong magnetic hyperfine field splitting below the Néel temperature.

Indides RE 3 T 2In4 (RE = Y, Gd–Tm, Lu; T = Ni, Ru, Rh) with a ZrNiAl superstructure

Abstract Three series of rare earth-transition metal-indides RE 3 T 2In4 (RE=Y, Gd–Tm, Lu; T=Ni, Ru, Rh) were synthesized from arc-melted RE 3 T 2 precursor compounds and indium tear shot in sealed niobium ampoules using different annealing sequences. The new indides crystallize with the hexagonal Lu3Co2In4-type structure, space group P6̅. All samples were characterized on the basis of Guinier powder patterns and six structures were refined from single crystal X-ray diffractometer data. The RE 3 T 2In4 structures are derived from the ZrNiAl type through RE/In ordering, paralleled by a symmetry reduction from P6̅2m to P6̅. This induces twinning for some of the investigated crystals. The main crystal chemical motifs of the RE 3 T 2In4 structures are trigonal prisms of rare earth, respectively indium atoms that are filled by the transition metals.

Crystal structure and phase transitions of ternary compounds in the thulium–silver–tin system

The existence of the TmAgSn compound in the Tm–Ag–Sn system in the form of two polymorphs was confirmed. The high-temperature phase crystallizes with the LiGaGe type (P63mc, Z = 2), and the lowtemperature one with the ZrNiAl type (\(P\overline 6 2m\), Z = 3). A new ternary compound TmAgSn2 was found to exist (Cu3Au type, \(Pm\overline 3 m\), Z = 1). The polymorphic transition temperature of the TmAgSn was found to be 1214 K using differential thermal analysis. A comparative investigation of the compounds by 119Sn Mossbauer spectroscopy showed a difference in the chemical bonding character of tin atoms: in TmAgSn2, tin has a typical valence state for metallic systems, whereas in both TmAgSn polymorphs additional interaction between the 5s orbitals of silver atoms and the 5p orbitals of tin atoms takes place.

Cerium intermetallics with ZrNiAl-type structure – a review

Abstract Equiatomic CeTX intermetallics with the hexagonal ZrNiAl type structure are formed with electron-rich transition metals (T) and X = Mg, Zn, Cd, Al, Ga, In, Tl, Sn, and Pb. Their crystal chemistry, chemical bonding, magnetic and electrical properties, and formation of solid solutions are reviewed. The results of 119Sn Mössbauer spectroscopy, high-pressure studies, and hydrogenation reactions are presented.