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.

Non-centrosymmetric superconductor Th[Formula: see text]Be[Formula: see text]Pt[Formula: see text] and heavy-fermion U[Formula: see text]Be[Formula: see text]Pt[Formula: see text] cage compounds.

Unconventional superconductivity in non-centrosymmetric superconductors has attracted a considerable amount of attention. While several lanthanide-based materials have been reported previously, the number of actinide-based systems remains small. In this work, we present the discovery of a novel cubic complex non-centrosymmetric superconductor [Formula: see text] ([Formula: see text] space group).

Micro-Scale Device-An Alternative Route for Studying the Intrinsic Properties of Solid-State Materials: The Case of Semiconducting TaGeIr.

An efficient application of a material is only possible if we know its physical and chemical properties, which is frequently obstructed by the presence of micro- or macroscopic inclusions of secondary phases. While sometimes a sophisticated synthesis route can address this issue, often obtaining pure material is not possible. One example is TaGeIr, which has highly sample-dependent properties resulting from the presence of several impurity phases, which influence electronic transport in the material.

μm- and nm-Sized Catalytic Structures in Heat Sources for Thermoelectric Generators.

Micro- and nano-structural organization and its influence on the efficiency of catalysts used in the heat sources for permeable thermoelectric generators were investigated. Two types of catalyst were studied–elemental platinum on aluminum oxide granulate Pt/Al₂O₃ and mixed transition-metal catalyst on fibrous silicon dioxide Co–Cr–Pd–Sr/SiO₂. The distribution of active components in catalytic structures which contribute to the maximum combustion completeness of organic fuel in heat sources was investigated.

Heteropolar bonding and a position-space representation of the 8 - N rule.

Chemical bonding models are one of the most powerful tools in chemistry and provide essential guidance in the understanding of composition and structure of chemical compounds, as well as in the development of new preparation routes. Facing the tremendous diversity of crystal structures and properties of intermetallic compounds, it is highly desirable to make the predictive power of chemical bonding models also available for this field of inorganic chemistry. Within the framework of quantum-chemical position-space analysis the concept of the 8 - N rule is recovered and extended for a consistent and quantitative treatment of heteropolar bonding situations as in compounds of the MgAgAs type and their relatives.

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.

Inelastic neutron scattering study of the lattice dynamics in the clathrate compound BaGe₅.

We report inelastic neutron scattering (INS) measurements on the polycrystalline oP60-type clathrate BaGe5, whose crystal structure is related to the type-I clathrate Ba8Ge43□3 and to the cP124-clathrate Ba6Ge25. Our results show that BaGe5 exhibits a similar phonon density of states (PDOS) in the energy range 0-40 meV with respect to Ba8Ge43□3. The low-energy region of the PDOS spectrum (0-10 meV) consists of two peaks at 4.

Electronic band structure and low-temperature transport properties of the type-I clathrate Ba8Ni(x)Ge(46-x-y□y).

We present the evolution of the low-temperature thermodynamic, galvanomagnetic and thermoelectric properties of the type-I clathrate Ba8Ni(x)Ge(46-x-y□y) with the Ni concentration studied on polycrystalline samples with 0.0 ≤ x ≤ 6.0 by means of specific heat, Hall effect, electrical resistivity, thermopower and thermal conductivity measurements in the 2-350 K temperature range and supported by first-principles calculations.

Synthesis and properties of type-I clathrate phases Rb(8-x-t)K(x□t)Au(y)Ge(46-y).

Type-I clathrates Rb(8-x-t)K(x□t)Au(y)Ge(46-y) are synthesized from Rb4Ge9, K4Ge9, Au, and Ge. Crystal structures and compositions are determined by single-crystal and powder X-ray diffraction methods. The lattice parameters are 10.

Diffusion-controlled formation of Ti2O3 during spark-plasma synthesis.

The spark-plasma-sintering (SPS) technique has successfully been applied for the single-step direct synthesis of Ti2O3 from a mixture of powders of rutile/anatase with titanium. The components react by diffusion through the grain boundaries, forming several intermediate phases locally. A single-phase material of titanium(III) oxide is obtained in compact bulk form after 180 min of SPS treatment at 1473 K.

Charge-doping-driven evolution of magnetism and non-Fermi-liquid behavior in the filled skutterudite CePt4Ge(12-x)Sb(x).

The filled skutterudite compound CePt(4)Ge(12) is situated close to the border between the intermediate valence of Ce and heavy-fermion behavior. Substitution of Ge by Sb drives the system into a strongly correlated and, ultimately, upon further increasing the Sb concentration, an antiferromagnetically ordered state. Our experiments evidence a delicate interplay of emerging Kondo physics and the formation of a local 4f moment.

Al13Fe4 as a low-cost alternative for palladium in heterogeneous hydrogenation.

Replacing noble metals in heterogeneous catalysts by low-cost substitutes has driven scientific and industrial research for more than 100 years. Cheap and ubiquitous iron is especially desirable, because it does not bear potential health risks like, for example, nickel. To purify the ethylene feed for the production of polyethylene, the semi-hydrogenation of acetylene is applied (80 × 10(6) tons per annum; refs 1-3).

Physical properties and crystal chemistry of Ce2Ga12Pt.

Single crystals of the new ternary compound Ce(2)Ga(12)Pt were prepared by the self-flux technique. The crystal structure with the space group P4/nbm was established from single crystal x-ray diffraction data and presents a derivative of the LaGa(6)Ni(0.6) prototype.

Structural transformation with "negative volume expansion": chemical bonding and physical behavior of TiGePt.

The synthesis and a joint experimental and theoretical study of the crystal structure and physical properties of the new ternary intermetallic compound TiGePt are presented. Upon heating, TiGePt exhibits an unusual structural phase transition with a huge volume contraction of about 10 %. The transformation is characterized by a strong change in the physical properties, in particular, by an insulator-metal transition.

Synthesis, crystal structure, and physical properties of the type-I clathrate Ba(8-δ)Ni(x)□(y)Si(46-x-y).

Type-I clathrate phase Ba(8)Ni(x)□(y)Si(46-x-y) (□ = vacancy) was obtained from the elements at 1000 °C with the homogeneity range 2.4 ≤ x ≤ 3.8 and 0 ≤ y ≤ 0.

PdGa intermetallic hydrogenation catalyst: an NMR and physical property study.

The PdGa intermetallic compound is a highly selective and stable heterogeneous hydrogenation catalyst for the semi-hydrogenation of acetylene. We have studied single crystals of PdGa grown by the Czochralski technique. The (69)Ga electric-field-gradient (EFG) tensor was determined by means of NMR spectroscopy, giving experimental confirmation of both the recently refined structural model of PdGa and the theoretically predicted Pd-Ga covalent bonding scheme.

Physical properties and valence state of cerium in the filled skutterudite CePt₄Ge₁₂.

Electronic, magnetic, and transport properties of the filled platinum-germanium skutterudite CePt₄Ge₁₂ are investigated. High resolution x-ray absorption spectroscopy measurements at the cerium L(III) edge demonstrate that CePt₄Ge₁₂ in this compound has a temperature-independent valence close to three. However, magnetic susceptibility, thermopower, Hall effect, and electronic specific heat reveal a broad maximum at Tmax D 65-80 K, suggesting the presence of valence fluctuations.

Magnetic properties and electronic structures of intermediate valence systems CeRhSi2 and Ce2Rh3Si5.

The crystal structures and the physical (magnetic, electrical transport and thermodynamic) properties of the ternary compounds CeRhSi(2) and Ce(2)Rh(3)Si(5) (orthorhombic CeNiSi(2)- and U(2)Co(3)Si(5)-type structures, respectively) were studied over wide ranges of temperature and magnetic field strength. The results revealed that both materials are valence fluctuating systems, in line with previous literature reports. Direct evidence for valence fluctuations was obtained by means of Ce L(III)-edge x-ray absorption spectroscopy and Ce 3d core-level x-ray photoelectron spectroscopy.

Intrinsic electrical and thermal properties from single crystals of Na24Si136.

The observation of intrinsic structural, electrical, and thermal properties from measurements on single-crystal specimens of clathrate-II Na24Si136 is reported, revealing metallic conduction in agreement with electronic structure calculations. Low-temperature heat capacity measurements corroborate a substantial electronic density of states at the Fermi level, and reveal an Einstein-like mode that can be attributed to Na guest "rattling". The large thermal conductivity of Na24Si136, compared to literature data for other intermetallic clathrates, can be understood in terms of the predominant electronic contribution for the fully filled Na24Si136 composition.

Crystal structure and transport properties of Ba8Ge43square3.

The single phase clathrate-I Ba(8)Ge(43)square(3) (space group Ia3d (no. 230), a = 21.307(1) A) was synthesized by quenching the melt between cold steel plates.

Atomic ordering and thermoelectric properties of the n-type clathrate Ba8Ni3.5Ge42.1square0.4.

Single crystals of the type-I clathrate Ba(8)Ni(3.5)Ge(42.1)square(0.

Superfluid density and energy gap function of superconducting PrPt4Ge12.

The filled skutterudite superconductor PrPt4Ge12 was studied in muon-spin rotation (muSR), specific heat, and electrical resistivity experiments. The continuous increase of the superfluid density with decreasing temperature and the dependence of the magnetic penetration depth lambda on the magnetic field obtained by means of muSR, as well as the observation of a T3 dependence of the electronic specific heat indicate the presence of pointlike nodes in the superconducting energy gap. The gap and the specific heat are found to be well described by two models with point nodes, similar to results obtained for the unconventional heavy fermion skutterudite superconductor PrOs4Sb12.

Electronic structure and thermodynamic properties of CeRh(2)Sn(4) and LaRh(2)Sn(4).

The electronic structure and thermodynamic properties of CeRh(2)Sn(4) and LaRh(2)Sn(4) are reported. The crystal structure of CeRh(2)Sn(4) has been determined from single-crystal diffraction experiments. The Ce core-level x-ray photoemission spectra and Ce L(III) x-ray absorption data unanimously indicate a stable trivalent state of the Ce ions in CeRh(2)Sn(4), consistent with static magnetic susceptibility.

EuTM(2)Ga(8) (TM = Co, Rh, Ir) - a contribution to the chemistry of the CeFe(2)Al(8)-type compounds.

The isostructural compounds EuTM(2)Ga(8) (TM = Co, Rh, Ir) were prepared by direct reaction of the elements by high-frequency thermal treatment. All three phases are isotypic with CeFe(2)Al(8) (space group Pbam, Pearson symbol oP44, Z = 4). The crystal structure was established from single-crystal X-ray diffraction data: a = 12.

Cationic clathrate I Si(46-x)P(x)Te(y) (6.6(1) < or = y < or = 7.5(1), x < or = 2y): crystal structure, homogeneity range, and physical properties.

A new cationic clathrate I Si(46-x)P(x)Te(y) (6.6(1) < or = y < or = 7.5(1), x < or = 2y at 1375 K) was synthesized from the elements and characterized by X-ray powder diffraction, thermal analysis, scanning electron microscopy, wavelength dispersive X-ray spectroscopy (WDXS), neutron powder diffraction, and (31)P NMR spectroscopy.