Discovery and Characterization of Antiferromagnetic UFeAs.

This work presents a study on a new uranium iron arsenide UFeAs. By implementing Bi-flux synthesis, we were able to grow mm-sized single crystals of this compound, which show twinning. UFeAs is one of only two known uranium iron arsenides.

Ordering by cation replacement in the system NaLiGa.

Samples of the pseudo-binary system NaLiGa ( ≤ 1) were synthesized from the elements at 300 °C in sealed Ta ampoules or by the reaction of NaGa with LiCl. The peritectic formation temperature decreases with increasing Li content from 501(2) °C ( = 0) to 489(2) °C ( = 1). The boundary compositions NaGa and NaLiGa crystallize with different structure types related by a group-subgroup relation.

NaGa: A Zintl-Wade Phase Related to "α-Tetragonal Boron".

NaGa crystallizes with the orthorhombic space group (no. 62; = 14.8580(6) Å, = 8.

Superconductivity of structurally disordered YIrSn.

The structural and physical properties of YIrSn grown from Sn-flux as large single crystals are studied. YIrSn crystallizes with a unique structure [space group 3̄, = 13.7706(1) Å], which is characterized by a strong disorder.

Crystal structure, phase transition and properties of indium(III) sulfide.

Poly- and single-crystalline samples of In0.67□0.33In2S4 thiospinel were obtained by various powder metallurgical and chemical vapor transport methods, respectively.

Crystal Structure and Physical Properties of the Cage Compound HfBIr.

HfBIr crystallizes with a new type of structure: space group , = 5.6300(3) Å, = 11.2599(5) Å, and = 3.

Crystal structure, chemical bonding, and electrical and thermal transport in ScRhSn.

Single crystals of ScRhSn were grown from Sn-flux. The crystal structure (SG: I4/acd, a = 13.5529(2) Å, c = 27.

Crystal structure and superconducting properties of ScIrSn.

ScIrSn crystallizes with a split variant of the TbRhSn structure type (space group I4/acd, [Formula: see text] [Formula: see text], [Formula: see text] [Formula: see text]). DFT calculations confirmed the instability of the structural arrangement with the fully occupied and unsplit crystallographic sites. High quality single crystals were grown from a Sn melt.

Ferromagnetic -FeMnN: High-Pressure Synthesis, Hardness and Magnetic Properties.

The iron manganese nitride FeMnN was obtained by high-pressure-high-temperature synthesis from -FeN and elemental Mn at 15(2) GPa and 1573(200) K. The phase crystallizes isostructural to binary -FeN. In comparison to the corresponding binary iron nitride, the microhardness of -FeMnN is reduced to 6.

High-Pressure Synthesis and Chemical Bonding of Barium Trisilicide BaSi₃.

BaSi₃ is obtained at pressures between 12(2) and 15(2) GPa and temperatures from 800(80) and 1050(105) K applied for one to five hours before quenching. The new trisilicide crystallizes in the space group 4 ¯ (no. 121) and adopts a unique atomic arrangement which is a distorted variant of the CaGe₃ type.

Distortions in the cubic primitive high-pressure phases of calcium.

The superconductivity in highly compressed calcium involves the occurrence of closely related low-symmetry structural patterns with an exceptionally low coordination number. Earlier theoretical and experimental results are controversial and some findings are inconsistent with our later observations in the pressure range up to 60 GPa. This situation motivated the present concerted computational and experimental re-investigation of the structural arrangement of calcium slightly above the high-pressure limit of the bcc arrangement at low-temperatures.

Lutetium Trigermanide LuGe: High-Pressure Synthesis, Superconductivity, and Chemical Bonding.

LuGe was obtained under high-pressure and high-temperature conditions at pressures between 8(1) and 14(2) GPa and at temperatures in the range from 1100(150) to 1500(150) K. The high-pressure phase is isotypic to DyGe and decomposes at ambient pressure and T = 690 K mainly into ( cF8)Ge and LuGe. Chemical bonding analysis of LuGe reveals two-center electron-deficient Ge-Ge bonds, multicenter polar Lu-Ge interactions, and lone pairs on germanium.

Cluster Formation in the Superconducting Complex Intermetallic Compound BePt.

Materials with the crystal structure of γ-brass type (CuZn type) are typical representatives of intermetallic compounds. From the electronic point of view, they are often interpreted using the valence electron concentration approach of Hume-Rothery, developed previously for transition metals. The γ-brass-type phases of the main-group elements are rather rare.

Intermediate-Valence Ytterbium Compound YbGaPt: Synthesis, Crystal Structure, and Physical Properties.

The title compound was synthesized by a reaction of the elemental educts in a corundum crucible at 1200 °C under an Ar atmosphere. The excess of Ga used in the initial mixture served as a flux for the subsequent crystal growth at 600 °C. The crystal structure of YbGaPt was determined from single-crystal X-ray diffraction data: new prototype of crystal structure, space group C2/m, Pearson symbol mS74, a = 7.

High-Pressure NiAs-Type Modification of FeN.

The combination of laser-heated diamond anvil cells and synchrotron Mössbauer source spectroscopy were used to investigate high-temperature high-pressure chemical reactions of iron and iron nitride Fe N with nitrogen. At pressures between 10 and 45 GPa, significant magnetic hyperfine splitting indicated compound formation after annealing at 1300 K. Subsequent in situ X-ray diffraction reveals a new modification of FeN with NiAs-type crystal structure, as also rationalized by first-principles total-energy and chemical-bonding studies.

Weak Interactions under Pressure: hp-CuBi and Its Analogues.

The metastable binary compound hp-CuBi was obtained from the direct chemical reaction between copper and bismuth at a pressure of 5 GPa and a temperature of 720 K. The atomic arrangement comprises slabs of puckered Cu layers sandwiched between Bi planes. The QTAIM charges calculated for compounds of bismuth with transition metals reveal negligible charge transfer for hp-CuBi.

On the transferability of electron density in binary vanadium borides VB, V3B4 and VB2.

Binary vanadium borides are suitable model systems for a systematic analysis of the transferability concept in intermetallic compounds due to chemical intergrowth in their crystal structures. In order to underline this structural relationship, topological properties of the electron density in VB, V3B4 and VB2 reconstructed from high-resolution single-crystal X-ray diffraction data as well as derived from quantum chemical calculations, are analysed in terms of Bader's Quantum Theory of Atoms in Molecules [Bader (1990). Atoms in Molecules: A Quantum Theory, 1st ed.

Disorder in the composite crystal structure of the manganese `disilicide' MnSi1.73 from powder X-ray diffraction data.

The crystal structure of the higher manganese silicide MnSi1.7 (known in the literature as HMS) is investigated in samples with different compositions obtained by different techniques at temperatures not higher than 1273 K. Powder X-ray diffraction was applied.

Intermetallic germanides with non-centrosymmetric structures derived from the Yb3Rh4Sn13 type.

New germanides with composition RE3Pt4Ge13 (RE = Y, Pr, Sm, Gd, Tb, Tm) have been prepared by high-pressure, high-temperature synthesis. Their crystal structures have been refined, and the relationship of this new rhombohedral and monoclinic structure types with the primitive cubic Yb3Rh4Sn13 prototype is discussed. Band structure calculations within density functional theory confirm the distorted rhombohedral and monoclinic structural arrangements to be energetically more favorable than the simple cubic one.

BaGe6 and BaGe(6-x): incommensurately ordered vacancies as electron traps.

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe6 (P = 15 GPa, T = 1073 K) and BaGe(6-x) (P = 10 GPa, T = 1073 K) which are metastable at ambient conditions. In BaGe(6-x), partial fragmentation of the BaGe6 network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe(6-x) is associated with the establishment of free electron pairs around the defects.

LiZn(4 - x) (x = 0.825) as a (3 + 1)-dimensional modulated derivative of hexagonal close packing.

The (3+1)-dimensional modulated structure of the LiZn(4 - x) (x = 0.825) binary compound has been determined in the superspace. The compound crystallizes in the orthorhombic superspace group Cmcm(α00)0s0 with a = 2.

New monoclinic phase at the composition Cu2SnSe3 and its thermoelectric properties.

A new monoclinic phase (m2) of ternary diamond-like compound Cu2SnSe3 was synthesized by reaction of the elements at 850 K. The crystal structure of m2-Cu2SnSe3 was determined through electron diffraction tomography and refined by full-profile techniques using synchrotron X-ray powder diffraction data (space group Cc, a = 6.9714(2) Å, b = 12.

Cs7Nd11(SeO3)12Cl16: first noncentrosymmetric structure among alkaline-metal lanthanide selenite halides.

Cs7Nd11(SeO3)12Cl16, the complex selenite chloride of cesium and neodymium, was synthesized in the NdOCl-SeO2-CsCl system. The compound has been characterized using single-crystal X-ray diffraction, electron diffraction, transmission electron microscopy, luminescence spectroscopy, and second-harmonic-generation techniques. Cs7Nd11(SeO3)12Cl16 crystallizes in an orthorhombic unit cell with a = 15.

TM7TM'6B8 (TM = Ta, Nb; TM' = Ru, Rh, Ir): new compounds with [B6] ring polyanions.

The ternary boron compounds TM(7)TM'(6)B(8) (TM = Ta, Nb; TM' = Ru, Rh, Ir) were prepared by high-temperature thermal treatment of mixtures of the elements. An analysis of the chemical bonding by the electron density/electron localizability approach reveals formation of covalently bonded polyanions [B(6)] and [TM'(6)B(2)]. The cationic part of the structure contains separated TM cations.