Diffractometer Data Research Articles

SrMg2Ga2 with ThCr2Si2-type structure

Abstract The gallide SrMg2Ga2 was obtained by direct reaction of the elements in a sealed tantalum ampoule. Single crystals were grown by slowly cooling the sample within a muffle furnace. The SrMg2Ga2 structure was refined from single crystal X-ray diffractometer data: I4/mmm, a = 450.52(7), c = 1169.39(18) pm, wR2 = 0.0349, 164 F 2 values, 11 variables. The magnesium and gallium atoms build up a three-dimensional [Mg2Ga2] network which is composed of layers of edge-sharing MgGa4 tetrahedra with 280 pm Mg–Ga. Adjacent layers are condensed by Ga–Ga bonding (253 pm). The strontium atoms fill large Ga8Mg8 cages. Electronic structure calculations within Density Functional Theory (DFT) show charge transfers from Sr and Mg to Ga with ionocovalent behavior. The electronic density of states is dominated by Ga states and reveals metallic behavior. The chemical bonding is strong with dominant Mg–Ga and Ga–Ga mixing.

Equiatomic intermetallic barium compounds BaTX (T=Pd, Pt, Au; X=Mg, Zn, Cd) with TiNiSi and ZrBeSi type structure

AbstractThe equiatomic ternary BaTX (T=Pd, Pt, Au; X=Mg, Zn, Cd) phases were obtained by reaction of the elements in sealed tantalum ampoules. The compounds were characterized through their X‐ray powder patterns. BaAuMg and BaTCd (T=Pd, Pt, Au) crystallize with the TiNiSi type structure, while the compounds BaTZn (T=Pd, Pt) adopt the ZrBeSi type. The structures of BaAuMg and BaPdZn were refined from single crystal X‐ray diffractometer data: Pnma, a=801.34(5), b=467.71(8), c=924.07(10) pm, wR2=0.0955, 736 F2 values, 20 variables for BaAuMg and P63/mmc, a=449.68(2), c=901.62(4) pm, wR2=0.1172, 145 F2 values, 8 variables for BaPdZn. The structures derive from the aristotype AlB2. The gold and magnesium atoms form puckered Au3Mg3 hexagons with 284–328 pm Au−Mg while the Pd3Zn3 hexagons in BaPdZn are planar (260 pm Pd−Zn). Comparison of all known BaTX phases shows a range of the valence electron count (VEC) from 13 (BaMnGe) to 18 (BaAuP). The BaTX phases crystallize with seven different structure types and there is no obvious correlation with VEC.

Ternary orthorhombic Laves phases Sr2Pd3Sn, Eu2Pd3Sn and Eu2Pd3In

Abstract The ternary Laves phases Sr2Pd3Sn, Eu2Pd3Sn and Eu2Pd3In were synthesized by induction melting of the elements in sealed tantalum ampoules. The polycrystalline products were characterized through their powder X-ray diffraction patterns. The structure of Eu2Pd3Sn was refined from single crystal X-ray diffractometer data: Mg2MnGa3 type, Cmcm, a = 583.36(5), b = 908.31(7), c = 958.06(8) pm, wR2 = 0.0366, 557 F 2 values, 23 variables. The palladium and tin atoms show the inverse coloring on the network of condensed tetrahedra of Mg2MnGa3, i.e., MnGa3 versus Pd3Sn. Refinement of the occupancy parameters revealed small defects for the europium site, leading to composition Eu1.962(6)Pd3Sn for the studied crystal. Sr2Pd3Sn is a Pauli paramagnet and Eu2Pd3Sn shows Curie-Weiss paramagnetism (7.86(1) µB Eu atom−1 and Θ P = 48.1(1) K). Ferromagnetic ordering is observed below T C = 46.1(1) K. The 119Sn and 151Eu Mössbauer spectra of Sr2Pd3Sn and Eu2Pd3Sn are discussed with respect to electron density changes as a function of the tin content and the ionicity in the sequence of the stannides Sr2Pd3Sn/Eu2Pd3Sn → Sr2Pd2Sn/Eu2Pd2Sn → EuPdSn → EuPdSn2.

Mössbauer-spectroscopic characterization of the stannides Sr2Pd2Sn and Eu2Pd2Sn

Abstract The Ca2Pd2Ge-type stannides Sr2Pd2Sn and Eu2Pd2Sn were synthesized by reaction of the elements in sealed tantalum ampoules in a high-frequency furnace and characterized by powder X-ray diffraction. The structure of Sr2Pd2Sn (Fdd2, a = 1063.95(5), b = 1623.22(9), c = 594.63(14) pm, wR2 = 0.0472, 972 F 2 values and 26 variables) was refined from single-crystal X-ray diffractometer data. The striking structural motif features equidistant chains formed by the palladium atoms (304.7 pm Pd–Pd), which are interlinked by the tin atoms (266.9 and 268.7 pm Pd–Sn). Together, the palladium and tin atoms form a three-dimensional [Pd2Sn] δ– polyanionic network in which the strontium atoms reside in larger cavities. The divalent character of europium in Eu2Pd2Sn was manifested by 151Eu Mössbauer spectroscopy. The isomer shift is δ = −9.48(1) mm s−1 at room temperature. The results of 119Sn Mössbauer-spectroscopic experiments have confirmed the tin site determined by the single-crystal study, the isomer shifts being δ = 1.71(1) mm s−1 for Eu2Pd2Sn and δ = 1.73(1) mm s−1 for Sr2Pd2Sn. Sr2Pd2Sn is a Pauli paramagnet with a susceptibility of 2.2(1) × 10−5 emu mol−1 at room temperature. Eu2Pd2Sn shows Curie-Weiss paramagnetism with an experimental magnetic moment of 7.85(1) µB per Eu atom, confirming divalent europium. The europium magnetic moments order antiferromagnetically at T N = 14 K.

Characterization of the 1-(5-(4,5-Dimethyl-1,3,2-dioxoborolan-2-yl)thiophen-2-yl)ethanone Using NMR 13C, 1H and 11B through the Density Functional Theory.

The use of computational methods that allow us to perform characterization on new compounds is not a novelty; nevertheless, the degree of complexity of the structures makes their study more challenging since new techniques and methods are required to adjust to the new structural model. The case of nuclear magnetic resonance characterization of boronate esters is fascinating because of its widespread use in materials science. In this paper, we use density functional theory to characterize the structure of the compound 1-[5-(4,5-Dimethyl-1,3,2-dioxaborolan-2-yl)thiophen-2-yl]ethanonea by means of nuclear magnetic resonance. We studied the compound in its solid form with the PBE-GGA and PBEsol-GGA functionals, with a set of plane wave functions and an augmented wave projector, which included gauge in CASTEP and its molecular structure with the B3LYP functional using the package Gaussian 09. In addition, we performed the optimization and calculation of the chemical shifts and isotropic nuclear magnetic resonance shielding of 1H, 13C, and 11B. Finally, we analyzed and compared the theoretical results with experimental diffractometric data observing a good approximation.

Eu2Ru3Si5 and Eu2Ir3Ga5 – first europium compounds with U2Mn3Si5-type structure but different europium valence

Abstract The silicide Eu2Ru3Si5 was synthesized from the elements in a sealed tantalum tube in a high-frequency furnace, while the gallide Eu2Ir3Ga5 was obtained by arc-melting. Both structures were refined from single-crystal X-ray diffractometer data: P4/mnc, a = 1072.69(8), c = 569.55(5) pm, wR = 0.0453, 617 F 2 values, 31 variables for Eu2Ru3Si5 and a = 1122.18(7), c = 583.17(4) pm, wR = 0.0546, 729 F 2 values, 31 variables for Eu2Ir3Ga4.95(1). The gallide shows small defects on one 8h site. The transition metal atoms in Eu2Ru3Si5 and Eu2Ir3Ga5 have octahedral p element coordination. These Ru@Si6 respectively Ir@Ga6 polyhedra are condensed to three-dimensional [Ru3Si5]6− respectively [Ir3Ga5]4− polyanionic networks. The ground states of Eu(III) in Eu2Ru3Si5 and Eu(II) in Eu2Ir3Ga5 were determined by 151Eu Mössbauer spectroscopy.

The palladium-rich silicides RE 3Pd20Si6 (RE = Sc, Y and Lu)

Abstract The silicides RE 3Pd20Si6 (RE = Sc, Y and Lu) were synthesized from the elements by arc-melting. The structures of Y3Pd20Si6 and Lu3Pd20Si6 were refined from single crystal X-ray diffractometer data: Mg3Ni20B6 type, F m 3 ‾ m $Fm\overline{3}m$ , a = 1216.04(8) pm, wR = 0.0328, 219 F 2 values, 14 variables for Y3Pd20Si6 and a = 1211.69(10) pm, wR = 0.0374, 217 F 2 values, 14 variables for Lu3Pd20Si6. The isotypy of Sc3Pd20Si6 was confirmed on the basis of a Guinier powder pattern (a = 1202.8(3) pm). The RE 3Pd20Si6 structures contain two crystallographically independent RE sites with relatively large coordination numbers, i.e. RE1@Pd16 and RE2@Pd12Si6. These polyhedra are arranged in a CaF2 related pattern with RE2@Pd12Si6 forming the fcc substructure and the RE1@Pd16 polyhedra filling the tetrahedral voids. The silicon atoms have slightly distorted square antiprismatic palladium coordination (4 × 239 pm Si–Pd1 and 4 × 245 pm Si–Pd2). Temperature dependent magnetic susceptibility measurements of the Lu3Pd20Si6 sample indicate Pauli paramagnetism.

Structure and 119Sn Mössbauer-spectroscopic characterization of BaRhSn2

Abstract The stannide BaRhSn2 was synthesized by induction melting of an arc-melted RhSn2 precursor compound with barium in a sealed tantalum ampoule. The structure of BaRhSn2 was refined from single-crystal X-ray diffractometer data: MgCuAl2 type, Cmcm, a = 437.56(4), b = 1242.35(10), c = 767.30(6) pm, wR2 = 0.0845, 469 F 2 values and 16 variables. The rhodium and tin atoms form a two-dimensional [RhSn2] δ− polyanionic network with short Rh–Sn (273–274 pm) and Sn–Sn (303–312 pm) distances. The large barium atoms lead to a substantial orthorhombic distortion of the (lonsdaleite-related) tin substructure, forcing a break of the Sn–Sn bond in b direction. This change in the tin substructure is reflected in the 119Sn Mössbauer spectrum. The tin atoms exhibit a higher s electron density which is expressed in an increased isomer shift of δ = 2.08(1) mm s−1 as compared to the previously reported stannide CaRhSn2 with a three-dimensional [RhSn2] δ− polyanionic network and δ = 1.96(4) mm s−1.

Tri-level resistive switching characteristics and conductive mechanism of HfO<sub>2</sub>/NiO<sub><i>x</i></sub>/HfO<sub>2</sub> stacks

<sec>With the extensive integration of portable computers and smartphones with “Internet of Things” technology, further miniaturization, high reading/writing speed and big storage capacity are required for the new-generation non-volatile memory devices. Compared with traditional charge memory and magnetoresistive memory, resistive random access memory (RRAM) based on transition metal oxides is one of the promising candidates due to its low power consumption, small footprint, high stack ability, fast switching speed and multi-level storage capacity.</sec><sec>Inspired by the excellent resistive switching characteristics of NiO and HfO<sub>2</sub>, NiO<sub><i>x</i></sub> films are deposited by magnetron sputtering on the Pt<inline-formula><tex-math id="Z-20230629144836">\begin{document}$\langle111\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144836.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144836.png"/></alternatives></inline-formula> layer and the polycrystalline HfO<sub>2</sub> film, respectively. Their microstructures, resistive switching characteristics and conductive mechanisms are studied. X-ray diffractometer data show the <inline-formula><tex-math id="Z-20230629144852">\begin{document}$\langle111\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144852.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144852.png"/></alternatives></inline-formula> preferred orientation for the NiO<sub><i>x</i></sub> film deposited on the Pt<inline-formula><tex-math id="Z-20230629144904">\begin{document}$\langle111\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144904.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144904.png"/></alternatives></inline-formula> layer but the <inline-formula><tex-math id="Z-20230629144913">\begin{document}$\langle100\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144913.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230629144913.png"/></alternatives></inline-formula> preferred one for the film deposited on the polycrystalline HfO<sub>2</sub> layer. X-ray photoelectron depth profile of Ni 2p core level reveals that the NiO<sub><i>x</i></sub> film is the mixture of oxygen-deficient NiO and Ni<sub>2</sub>O<sub>3</sub>. NiO<sub><i>x</i></sub>(111) films show bipolar resistive switching (RS) characteristics with a clockwise current-voltage (<i>I-V</i>) loop, but its ratio of the high resistance to the low resistance (<i>R</i><sub>H</sub>/<i>R</i><sub>L</sub>) is only ~10, and its endurance is also poor. The NiO<sub><i>x</i></sub>(200)/HfO<sub>2</sub> stack exhibits bipolar RS characteristics with a counterclockwise <i>I-V</i> loop. The <i>R</i><sub>H</sub>/<i>R</i><sub>L</sub> is greater than 10<sup>4</sup>, the endurance is about 10<sup>4</sup> cycles, and the retention time exceeds 10<sup>4</sup> s. In the initial stage, the HfO<sub>2</sub>/NiO<sub><i>x</i></sub>(200)/HfO<sub>2</sub> stack shows similar bi-level RS characteristics to the NiO<sub><i>x</i></sub>(200)/HfO<sub>2</sub> stack. However, in the middle and the last stages, its <i>I-V</i> curves gradually evolve into tri-level RS characteristics with a “two-step Setting process” in the positive voltage region, showing potential applications in multilevel nonvolatile memory devices and brain-like neural synapses. Its <i>I-V</i> curves in the high and the low resistance state follow the relationship of ohmic conduction (<inline-formula><tex-math id="Z-20230714031758-1">\begin{document}$ I \propto V $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230714031758-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230714031758-1.png"/></alternatives></inline-formula>), while the <i>I-V</i> curves in the intermediate resistance state are dominated by the space-charge-limited-current mechanism (<inline-formula><tex-math id="Z-20230714031758-2">\begin{document}$ I \propto V^2 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230714031758-2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230331_Z-20230714031758-2.png"/></alternatives></inline-formula>). The tri-level RS phenomena are attributed to the coexistence of the oxygen-vacancy conductive filaments in the NiO<sub><i>x</i></sub>(200) film and the space charge limited current in the upper HfO<sub>2</sub> film.</sec>

TiNiSi-type YbIrMg with trivalent ytterbium

Abstract YbIrMg was obtained from a reaction of the elements in an equiatomic ratio in a sealed tantalum ampoule in a muffle furnace. The TiNiSi-type structure of YbIrMg was refined from single crystal X-ray diffractometer data: Pnma, a = 695.72(3), b = 405.84(6), c = 840.57(7) pm, wR = 0.0431, 511 F 2 values and 21 variables. A small degree of Mg/Ir mixing within the three-dimensional [IrMg] network leads to the refined composition YbIr1.024(4)Mg0.976(4). The course of the cell volume in the REIrMg series (Iandelli plot) points to trivalent ytterbium in YbIrMg.

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.

Crystallographic and photoluminescence studies on the solid solution Li3Ba2La3–xPrx(WO4)8 (x = 0–3)

The present work deals with a series of samples belonging to the solid solution according to Li3Ba2La3–xPrx(WO4)8 (x = 0–3). Exemplarily, the structures of Li3Ba2La3(WO4)8 and Li3Ba2La1.5Pr1.5(WO4)8 (RbLiBi2(MoO4)4 type, space group C2/c, Z = 2) were refined from single crystal X-ray diffractometer data. Other microcrystalline powder samples were characterised by powder X-ray diffraction and a range of spectroscopic methods such as diffuse reflection or temperature dependent excitation and emission measurements. Furthermore, the photoluminescence decay behaviour was examined. In addition, a mathematical approach is presented to explain the temperature induced changes in the emission intensities of the 3PJ based emission features of the praseodymium.

Sc2In-based solid solutions in the Sc-Fe-In and Sc-Au-In systems

Abstract Phase analytical studies in the scandium-rich parts of the Sc-T-In systems (T = Fe, Au) revealed the formation of small areas of solid solutions Sc2−x Fe x In and Sc2Au x In1−x that are derived from the binary Ni2In-type phase Sc2In, space group P63/mmc. The samples were synthesized from the elements in sealed tantalum ampoules in an induction furnace. The structures of Sc1.88Fe0.12In (a = 498.37(6), c = 630.94(8) pm, wR2 = 0.0603, 124 F 2 values, nine variables), Sc2Au0.37In0.63 (a = 494.65(5), c = 632.42(6) pm, wR2 = 0.0639, 123 F 2 values, nine variables) and Sc2Au0.22In0.78 (a = 496.09(3), c = 628.29(4) pm, wR2 = 0.0331, 124 F 2 values, nine variables) were refined from single-crystal diffractometer data. Sc1.88Fe0.12In shows Sc/Fe mixing on Wyckoff position 2a, while gold is substituted for indium on site 2c. Analyses of the reciprocal space gave no hint for superstructure formation, and the three refinements show slightly enhanced U 33 displacement parameters for the 2d scandium sites which react on the mixed occupancies.

Magnesium-rich intermetallic compounds RE 3Ag4Mg12 (RE = Y, La–Nd, Sm–Dy, Yb) and AE 3Ag4Mg12 (AE = Ca, Sr)

Abstract The magnesium-rich intermetallic compounds RE 3Ag4Mg12 (RE = Y, La–Nd, Sm–Dy, Yb) and AE 3Ag4Mg12 (AE = Ca, Sr) were synthesized from the elements in sealed tantalum ampoules through heat treatment in an induction furnace. X-ray powder diffraction studies confirm the hexagonal Gd3Ru4Al12 type structure, space group P63/mmc. Three structures were refined from single crystal X-ray diffractometer data: a = 973.47(5), c = 1037.19(5) pm, wR2 = 0.0296, 660 F 2 values, 30 variables for Gd3Ag3.82(1)Mg12.18(1), a = 985.27(9), c = 1047.34(9) pm, wR2 = 0.0367, 716 F 2 values, 29 variables for Yb3Ag3.73(1)Mg12.27(1) and a = 992.41(8), c = 1050.41(8) pm, wR2 = 0.0373, 347 F 2 values, 28 variables for Ca3Ag3.63(1)Mg12.37(1). Refinements of the occupancy parameters revealed substantial Ag/Mg mixing within the silver-magnesium substructure, a consequence of the Ag@Mg8 coordination. The alkaline earth and rare earth atoms build Kagome networks. Temperature dependent magnetic susceptibility measurements indicate diamagnetism/Pauli paramagnetism for the compounds with Ca, Sr, Y and YbII, while the others with the trivalent rare earth elements are Curie-Weiss paramagnets. Most compounds order antiferromagnetically at T N = 4.4(1) K (RE = Pr), 34.6(1) K (RE = Gd) and 23.5(1) K (RE = Tb) while Eu3Ag4Mg12 is a ferromagnet (T C = 19.1(1) K). 151Eu Mössbauer spectra confirm divalent europium (δ = −9.88(1) mm s−1). Full magnetic hyperfine field splitting (18.4(1) T) is observed at 6 K. Yb3Ag4Mg12 shows a single resonance in its 171Yb solid state NMR spectrum at 6991 ppm at 300 K indicating a strong, positive Knight shift.

APd2Zn3 (A=Ca, Sr, Eu) with a CaCu5 superstructure

AbstractThe intermetallic phases APd2Zn3 (A=Ca, Sr, Eu) were synthesized from the elements in sealed niobium ampules in an induction furnace. The phase purity of the samples was checked by powder X‐ray diffraction (Guinier technique). The structures were refined from single crystal X‐ray diffractometer data: YNi2Al3 type (CaCu5 superstructure), P6/mmm, a=936.97(4), c=420.75(2) pm, wR2=0.0206, 259 F2 values, 17 variables for CaPd2Zn3, a=953.63(6), c=425.38(3) pm, wR2=0.0185, 230 F2 values, 17 variables for SrPd2Zn3 and a=948.20(7), c=423.20(3) pm, wR2=0.0209, 228 F2 values, 18 variables for EuPd2.12(1)Zn2.88(1). The europium‐based crystal showed a small homogeneity range through Pd/Zn mixing. The striking structural motifs of the APd2Zn3 phases are Kagome networks formed by the palladium and zinc atoms. The superstructure formation (discussed on the basis of a Bärnighausen tree) results from a different Pd/Zn coloring and a shift of one A position by c/2. The divalent character of europium in EuPd2Zn3 was substantiated by magnetic susceptibility and 151Eu Mössbauer spectroscopic measurements. EuPd2Zn3 orders ferrimagnetically at TC=17.5(5) K. The magnetization behavior at 3 K (two‐step magnetization) confirms the existence of two crystallographically independent europium sites. The 151Eu Mössbauer spectrum at 5 K shows full magnetic hyperfine field splitting (δ=−8.99(4) mm s−1 and BHf=27.7(1) T).

Lu26 T 17–x In x (T = Rh, Ir, Pt) – first indium intermetallics with Sm26Co11Ga6-type structure

Abstract Several Lu26 T 17−x In x (T = Rh, Ir, Pt) phases with varying x values were obtained by induction-melting reactions of the elements in sealed tantalum ampoules. All samples were characterized through their X-ray powder diffraction patterns. These compounds crystallize with the tetragonal Sm26Co11Ga6-type structure, space group P4/mbm and Z = 2. The structure of Lu26Pt7.55In9.45 has been refined from single-crystal X-ray diffractometer data: a = 1165.32(5), c = 1547.46(6) pm, wR2 = 0.0895, 2173 F 2 values and 70 variables. The Lu26 T 17−x In x phases are the first indium representatives of the Sm26Co11Ga6 type. They belong to the n = 4 members of Parthé’s A 5n+6 B 3n+5 series, which show different stacking sequences of square prisms and antiprisms. Lu26Pt7.55In9.45 as a lutetium-rich intermetallic compound exhibits a broader range of shorter Lu–Lu distances (341–375 pm). Temperature dependent magnetic susceptibility measurements show Pauli paramagnetism for Lu26Ir8.5In8.5 and Lu26Rh7In10 with room temperature values of the magnetic susceptibility of χ = 1.53 × 10−3 emu mol−1 for Lu26Rh7In10 and χ = 6.54 × 10−4 emu mol−1 for Lu26Ir8.5In8.5.

Mg2MnGa3 – An orthorhombically distorted superstructure variant of the hexagonal Laves phase MgZn2

Abstract The Laves phase Mg2MnGa3 was synthesized from the elements by arc-melting and subsequent annealing in a silica ampoule at T = 670 K. The structure of Mg2MnGa3 was refined from single-crystal X-ray diffractometer data: URe2 type, Cmcm, a = 543.24(1), b = 869.59(3), c = 858.58(2) pm, wR2 = 0.0556, 273 F 2 values and 24 variables. The manganese and gallium atoms form a three-dimensional network of corner- and face-sharing MnGa3 tetrahedra that derive as a ternary ordering variant from the hexagonal Laves phase MgZn2. The structures of the distortion and coloring variants, i.e., MgZn2, URe2, Mg2Cu3Si and Mg2MnGa3 are discussed on the basis of a Bärnighausen tree. The electronic structure calculation data indicate that in addition to the metallic type of bonding an additional covalent interaction appears between the Ga–Ga and Mn–Ga atoms.

Intermetallic compounds RE 2Ga2Mg (RE = Tb–Tm, Lu) with Mo2B2Fe-type structure

Abstract The rare earth intermetallic compounds RE 2Ga2Mg with RE = Tb–Tm and Lu were synthesized from the elements in sealed tantalum ampoules in a high-frequency furnace. These rare earth-rich phases crystallize with the tetragonal Mo2B2Fe-type structure, space group P4/mbm and Z = 2. The polycrystalline samples were characterized through their Guinier powder patterns. The structures of Er2Ga2.092(1)Mg0.908(1), Tm2Ga2.037(1)Mg0.963(1) and Lu2Ga2.176(1)Mg0.824(1) have been refined from single crystal X-ray diffractometer data. The refinements revealed small homogeneity ranges (small degrees of Mg/Ga mixing on the 2a sites). The magnesium atoms show square planar coordination by Ga2 dumbbells (282 pm Mg–Ga and 257 pm Ga–Ga in the lutetium compound). Geometrically one can describe the RE 2Ga2Mg phases as 1:1 intergrowth structures of CsCl and AlB2-related slabs of compositions REMg and REGa2. From DFT based calculations, charge transfer from the rare earth and magnesium atoms towards gallium can be illustrated in electron localization function ELF slice planes showing strong localization around gallium in the basal plane as well as along the tetragonal c axis signaling Ga–Ga pair interactions. The site-projected density of states DOS and COOP data further quantify this observation. Temperature dependent magnetic susceptibility measurements show Pauli paramagnetism for Sc2Ga2Mg and Lu2Ga2Mg with low room temperature susceptibility values of 2.1(1) × 10−4 and 1.1(1) × 10−4 emu mol−1, respectively. Ho2Ga2Mg, Er2Ga2Mg and Tm2Ga2Mg are Curie-Weiss paramagnets with stable trivalent rare earth ground states. Antiferromagnetic ordering was detected below the Néel temperatures of T N = 18.6(1) (RE = Ho), 11.9(1) (RE = Er) and 6.4(1) K (RE = Tm). The three compounds show metamagnetic transitions in their 3 K magnetization isotherms. Tm2Ga2Mg exhibits a square loop behavior with small hysteresis.

Intermediate ytterbium valence in YbRhSn2

Abstract The stannide YbRhSn2 has been synthesized. An arc-melted Rh25Sn48 precursor sample was reacted with ytterbium in a sealed tantalum ampoule in an induction furnace. The structure of YbRhSn2 was refined from single-crystal X-ray diffractometer data: MgCuAl2 type, Cmcm, a = 433.10(3), b = 1076.63(8), c = 739.36(5) pm, wR2 = 0.0676, 444 F 2 values and 16 variables. The rhodium and tin atoms form a three-dimensional [RhSn2] δ− polyanionic network with short Rh–Sn (271–273 pm) and Sn–Sn (301–324 pm) distances. The tin substructure is an orthorhombically distorted lonsdaleite network. YbRhSn2 shows paramagnetic behavior with a reduced magnetic moment of 2.2(1) µB per ytterbium atom, classifying it as an intermediate-valent compound.

Lu37Ru16.4In4 – coloring and vacancy formation in a new structure type closely related to a 8 × 8 × 8 bcc superstructure

Abstract The lutetium-rich intermetallic compound Lu37Ru16.4In4 was synthesized by induction melting of the elements in a sealed tantalum ampoule and subsequent annealing. The Lu37Ru16.4In4 structure was refined from single crystal X-ray diffractometer data: new type, I a 3 ‾ d $Ia\overline{3}d$ , a = 2756.21(11) pm, wR2 = 0.0579, 3056 F 2 values and 92 variables. The superstructure formation of Lu37Ru16.4In4 is discussed on the basis of a group–subgroup scheme starting from the bcc structure as the aristotype.