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Exceptionally electron‐rich, nearly trigonal‐planar tricyanidometalate anions [Fe(CN)3]7− and [Ru(CN)3]7− were stabilized in LiSr3[Fe(CN)3] and AE3.5[M(CN)3] (AE=Sr, Ba; M=Fe, Ru). They are the first examples of group 8 elements with the oxidation state of −IV. Microcrystalline powders were obtained by a solid‐state route, single crystals from alkali metal flux. While LiSr3[Fe(CN)3] crystallizes in P63/m, the polar space group P63 with three‐fold cell volume for AE3.5[M(CN)3] is confirmed by second harmonic generation. X‐ray diffraction, IR and Raman spectroscopy reveal longer C−N distances (124–128 pm) and much lower stretching frequencies (1484–1634 cm−1) than in classical cyanidometalates. Weak C−N bonds in combination with strong M−C π‐bonding is a scheme also known for carbonylmetalates. Instead of the formal notation [Fe−IV(CN−)3]7−, quantum chemical calculations reveal non‐innocent intermediate‐valent CN1.67− ligands and a closed‐shell d10 configuration for Fe, that is, Fe2−., The electron‐rich cyanidometalates [Fe(CN)3]7− and [Ru(CN)3]7− represent the first examples of group 8 elements with an oxidation state of −IV. DFT calculations reveal a nominal d10s0 configuration, which corresponds to an effective charge of 2−. The high negative charge also weakens the C−N bonds by the population of antibonding states.

Rb8B8Si38 forms under high-pressure, high-temperature conditions at p = 8 GPa and T = 1273 K. The new compound (space group Pm3n, a = 9.9583(1) A) is the second example for a clathrate-I borosilicide. The phase is inert against strong acids and bases and thermally stable up to 1300 K at ambient pressure. (Rb+)8(B-)8(Si0)38 is electronically balanced, diamagnetic, and shows semiconducting behavior with moderate Seebeck coefficient below 300 K. Chemical bonding analysis by the electron localizability approach confirms the description of Rb8B8Si38 as Zintl phase.

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. The effect of these minority phases was avoided by manufacturing, with the help of focused‐ion‐beam, a μm‐scale device containing only one phase—TaGeIr. This work provides evidence for intrinsic semiconducting behavior of TaGeIr and serves as an example of selective single‐domain device manufacturing. This approach gives a unique access to the properties of compounds that cannot be synthesized in single‐phase form, sparing costly and time‐consuming synthesis efforts., Perfection not required: In a study of intrinsic properties of intermetallic compounds, the synthesis of either single‐crystal or single‐phase material is the fundamental step. However, some materials cannot be prepared in single‐phase form. A new approach using a micro‐scale amount of material to study its intrinsic properties can significantly shorten this procedure and make the quest for “perfect” samples unnecessary.

The clathrate I superconductor Sr8 Si46 is obtained under high-pressure high-temperature conditions, at 5 GPa and temperatures in the range of 1273 to 1373 K. At ambient pressure, the compound decomposes upon heating at T=796(5) K into Si and SrSi2 . The crystal structure of the clathrate is isotypic to that of Na8 Si46 . Chemical bonding analysis reveals conventional covalent bonding within the silicon network as well as additional multi-atomic interactions between Sr and Si within the framework cages. Physical measurements indicate a bulk BCS type II superconducting state below Tc =3.8(3) K.

A new approach for in-situ synthesis of crystalline Co–Fe–B nanoparticles was presented in which low temperature methods were developed by using metal chlorides and NaBH4 in an inorganic molten salt environment. Effects of different reaction systems/conditions on the phase formation, thermal behavior and microstructure were investigated. The melting point of reactants and impurities in final powders were reduced by the use of molten salt technique. After a reaction of CoCl2, FeCl3 and NaBH4 at 850 °C in sealed tubes, CoB and Fe3B phases formed separately. After a reaction under Ar flow; however, CoFeB2 solid solution nano powders were obtained in one step at 850 °C with an average size of 60 nm. After annealing at 1100 °C, stable and highly crystalline (CoFe)B2 solid solution phase with a Co:Fe molar ratio of 1:1 was achieved. As-synthesized particles exhibited ferromagnetic property, and possessed a narrow hysteresis curve characteristic of soft magnetic materials. Extended reaction temperature from 650 to 850 °C is seen to produce coercivity enhancement up to 500 Oe without significant reduction in saturation magnetization. On the other hand, after an annealing process and subsequent phase and chemical change, crystalline (CoFe)B2 particles exhibited superparamagnetic property.

The silicon-rich cage compound MgSi5 was obtained by high-pressure high-temperature synthesis. Initial crystal structure determination by electron diffraction tomography provided the basis for phase analyses in the process of synthesis optimization, finally facilitating the growth of single crystals suitable for X-ray diffraction experiments. The crystal structure of MgSi5 (space group Cmme, Pearson notation oS24, a=4.4868(2) A, b=10.1066(5) A, and c=9.0753(4) A) constitutes a new type of framework of four-bonded silicon atoms forming Si15 cages enclosing the Mg atoms. Two types of smaller Si8 cages remain empty. The atomic interactions are characterized by two-center two-electron bonds within the silicon framework. In addition, there is evidence for multi-center Mg-Si bonding in the large cavities of the framework and for lone-pair-like interactions in the smaller empty voids.

The crystal structure of the (Cr,Ni)4Si phase with and without Co was refined from X-ray powder diffraction data. The compound crystallises with an Au4Al-type structure (Pearson symbol cP20, space group P213): unit-cell parameter a = 0.611959(6) nm for the composition (Cr0.312Ni0.688)4Si, a = 0.612094(6) nm for (Cr0.375Ni0.625)4Si, and a = 0.612316(6) nm for (Cr0.337Co0.063Ni0.600)4Si. The magnetic susceptibility was measured in external fields up to 7 T at temperatures between 1.8 and 400 K. The three investigated samples exhibited paramagnetic behaviour described by the modified Curie-Weiss law: χ0 = 146∙10-6 emu g-at.-1, μeff = 0.21 μB/atom, θP = -13 K for (Cr0.312Ni0.688)4Si; χ0 = 158∙10-6 emu g-at.-1, μeff = 0.20 μB/atom, θP = -15 K for (Cr0.375Ni0.625)4Si; χ0 = 169∙10-6 emu g-at.-1, μeff = 0.18 μB/atom, θP = -52 K for (Cr0.337Co0.063Ni0.600)4Si.

Thermomechanically active shape-programmable elastomer microparticles are very promising for development of particulate composites with unique operational properties, which could be attractive for various applications, e.g., in 3D printing. Liquid crystal elastomers are one of the suitable candidate materials due to their remarkable spontaneous shape change response. Performed rheological and thermomechanical tests demonstrate that shear stress can be used to efficiently manipulate the nematic order-driven morphology of liquid crystal elastomer microparticles (μLCEs). Specifically, by exploiting the soft-elasticity character of the material through manipulation of shear amplitude time profile, the nematic director can be oriented along the flow, which results in alignment of microparticles. Using this method, a suspension of well-aligned, thermomechanically elongated monodomain μLCEs can be created by shear stress-assisted cooling. Although the alignment can be lost in absence of persistent flow, it is restored instantaneously on re-application of the flow. The reason for this is the preservation of particle elongation at room temperature in zero flow. This shape memory can be erased by heating the system to the isotropic phase. Our work represents an important step forward in the development of a new generation of shape-programmable materials, which are potentially suitable for additive manufacturing of artefacts with anisotropic physical properties.

Chemical synthesis of crystalline and nanoscale cobalt-iron metal boride powders was studied using hydrous metal chlorides and NaBH4. The effects of precursor concentration and optimized synthesis conditions on the phase formation, microstructure, and magnetic properties were investigated. After applying a reaction of CoCl2·6H2O-FeCl3·6H2O-NaBH4 at 850 °C, (CoFe)B2, (CoFe)B, Co2B, Fe3B, and Fe0.71Co0.29 boride phases were obtained from different synthesis conditions applied under autogenic pressure or Ar flow atmosphere. Oxychloride impurities were the reason for the reduced magnetization values. The highest saturation magnetization of 183 emu/g belongs to obtained nanoparticles containing (CoFe)B2 and (CoFe)B pure phases. High temperature magnetic measurements marked synthesized powders as soft magnetic materials up to 795 K while no Tc was reached for the obtained phases., Scientific and Technological Research Council of Turkey (TÜBİTAK); Novel Low Temperature Synthesis of Cobalt–Metal–Boron (Metal = Ni, Fe, Ti) Based Ternary Metal Borides from Metal Chlorides: Characterization and Application Oriented Investigations on Catalyzer/Magnet/Hybrid Composite Fabrication Project

${\mathrm{TaSnS}}_{2}$ single crystal and polycrystalline samples are investigated in detail by magnetization, electrical resistivity, and specific heat as well as Raman spectroscopy and nuclear magnetic resonance (NMR). Studies are focused on the temperature and magnetic field dependence of the superconducting state. We determine the critical fields for both directions $B\ensuremath{\parallel}c$ and $B\ensuremath{\perp}\phantom{\rule{0.16em}{0ex}}c$. Additionally, we investigate the dependence of the resistivity, the critical temperature, and the structure through Raman spectroscopy under high pressure up to 10 GPa. At a pressure of $\ensuremath{\approx}3\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ the superconductivity is suppressed below our minimum temperature. The Sn NMR powder spectrum shows a single line which is expected for the ${\mathrm{TaSnS}}_{2}$ phase and confirms the high sample quality. Pronounced de Haas-van Alphen oscillations in the ac susceptibility of polycrystalline sample reveal two pairs of frequencies indicating coexisting small and large Fermi surfaces. The effective mass of the smaller Fermi surface is $\ensuremath{\approx}0.5{m}_{\mathrm{e}}$. We compare these results with the band structures from DFT calculations. Our findings on ${\mathrm{TaSnS}}_{2}$ are discussed in terms of a quasi-two-dimensional BCS superconductivity.

Synthetic bulk and natural pyrite from the hydrothermal mine in Schonbrunn (Saxony, Germany) are confirmed to be stoichiometric FeS2 compounds and stable (for thermoelectric applications) up to ∼600 K by combined thermal, chemical, spectroscopic and X-ray diffraction analyses. Natural pyrite with a small amount (

A detailed study of polycrystalline indium-based In1-x□xIn2S4 (x = 0.16, 0.22, 0.28, and 0.33) thiospinel is presented (□- vacancy). Comprehensive investigation of synthesis conditions, phase composition and thermoelectric properties was performed by means of various diffraction, microscopic and spectroscopic methods. Single-phase α- and β-In1-x□xIn2S4 were found in samples with 0.16 ≤x≤ 0.22 and x = 0.33 (In2S3), respectively. In contrast, it is shown that In0.72□0.28In2S4 contains both α- and β-polymorphic modifications. Consequently, the thermoelectric characterization of well-defined α- and β-In1-x□xIn2S4 is conducted for the first time. α-In1-x□xIn2S4 (x = 0.16 and 0.22) revealed n-type semiconducting behavior, a large Seebeck coefficient (>|200|μV K-1) and moderate charge carrier mobility on the level of ∼20 cm2 V-1 s-1 at room temperature (RT). Decreases in charge carrier concentration (increase of electrical resistivity) and thermal conductivity (even below 0.6 W m-1 K-1 at 760 K) for larger In-content are observed. Although β-In0.67□0.33In2S4 (β-In2S3) is a distinct polymorphic modification, it followed the abovementioned trend in thermal conductivity and displayed significantly higher charge carrier mobility (∼104 cm2 V-1 s-1 at RT). These findings indicate that structural disorder in the α-modification affects both electronic and thermal properties in this thiospinel. The reduction of thermal conductivity counterbalances a lowered power factor and, thus, the thermoelectric figure of merit ZTmax = 0.2 at 760 K is nearly the same for both α- and β-In1-x□xIn2S4.

This work presents the heat capacity of four lithium stannides Li17Sn4, Li7Sn2, Li13Sn5 and Li7Sn3 covering a temperature range from (2 to 865) K. Two different calorimeters depending on their specification were used. A calorimetric method based on a relaxation technique was applied in the low temperature region from (2 to 300) K and data between (300 to 865) K were measured with a DSC utilising the Cp-by-step method. The accuracy of the experimental data is better than ± 2% above 20 K and rises up to 20% below 20 K. The obtained data were split into appropriate temperature intervals and fitted to common heat capacity functions. The low temperature measurement permits the calculation of the standard entropy and entropy of formation as well as temperature coefficients of electronic and lattice contributions to the heat capacity. This study represents a significant improvement of the data basis for thermodynamic calculations (e.g. CALPHAD) and to the understanding of electrochemical equilibria in the Li-Sn-System.

The structural properties of modulated SrGe6− x (x≈0.45) were investigated by means of single-crystal and powder X-ray diffraction combined with quantum chemical calculations. The framework compound SrGe6− x adopts a defect variant of the EuGa2Ge4-type crystal structure. Samples of the binary compound with nominal compositions 0≤x≤0.5 were synthesized at pressures from 5 to 6 GPa and a temperature of typically 1400 K. The product reveals diffraction peaks of the EuGa2Ge4-type subcell plus additional reflections indicating an ordered superstructure. Detailed crystal structure analysis evidences the incommensurate nature of the superstructure and a modulation of the vacancy ordering in the germanium network. The computations have shown that the non-stoichiometric composition of the framework with its local defect organization affects the calculated charge of the strontium anions. Although the chemical composition is close to a charge-balanced situation, temperature-dependent resistivity measurements showed metal-type conductivity. At ambient pressure SrGe6− x decomposes exothermally and irreversibly at T=680(10) K into SrGe2 and germanium, indicating its metastable nature at ambient pressure.

Two new calcium nitridomanganates, Ca12 [Mn19 N23 ] (P3, a=11.81341(3) A, c=5.58975(2) A, Z=1) and Ca133 [Mn216 N260 ] (P3‾ , a=39.477(1) A, c=5.5974(2) A, Z=1), were obtained by a gas-solid reaction of Ca3 N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12 [Mn19 N23 ] was determined from high-resolution X-ray synchrotron powder diffraction data, whereas single-crystal X-ray diffraction was employed to establish the crystal structure of the Ca133 [Mn216 N260 ] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal-metal bond formation.

LuGe3 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 DyGe3 and decomposes at ambient pressure and T = 690 K mainly into ( cF8)Ge and LuGe2- x. Chemical bonding analysis of LuGe3 reveals two-center electron-deficient Ge-Ge bonds, multicenter polar Lu-Ge interactions, and lone pairs on germanium. Magnetic susceptibility, specific heat, and electrical conductivity measurements indicate transition into a superconducting state below Tc = 3.3(3) K.

Several Mn-based compounds have been identified as promising materials to replace permanent magnetic alloys based on rare earth elements. Amongst them is the compound BiMn, in particular the low temperature modification α-BiMn (hP4, AsNi-type, B81), which has been shown to exhibit interesting magnetic properties. In the present study, it was attempted to synthesize phase-pure α-BiMn by annealing samples at 320 °C and centrifuging them at this temperature. In this way, it was possible to obtain a distinct phase separation with the intermetallic compound on top and the liquid Bi, which is always present after the high-temperature syntheses, at the bottom. After solidification, α-BiMn with a purity of up to 87%, though not phase-pure, could be recovered. Thermal analyses as well as the temperature dependence of the magnetization indicated a peritectic decomposition at 355 ± 2 °C whereas the phase re-formed on cooling at 341 ± 2 °C. High-temperature X-ray diffraction led to a complete oxidation of the sample even in a rather pure He atmosphere. Magnetic measurements showed an increase of the coercivity of α-BiMn with increasing temperature, in general agreement with earlier literature reports. The Curie temperature could not be determined experimentally as it is apparently higher than the temperature of the peritectic decomposition.

Sodium is widely used as a substituting element in p-type PbTe-based thermoelectric materials. In this work, two series of polycrystalline samples Pb1–yNayTe1–y/2 (total charge balance) and Pb1–xNaxTe (total charge nonbalance) were examined. Na has limited solubility for both of the series. The MAS 23Na NMR analysis of Pb1–xNaxTe series (for Pb0.98Na0.02Te sample after spark-plasma sintering, SPS) reveals only one Na signal, corresponding to Na atoms coordinated by six Te atoms, indicating substitution of Pb by Na without defects in the Te sublattice. In the Pb1–yNayTe1–y/2 series, clustering of Na atoms with reduced coordination by Te was observed. Additional heat treatment of these samples leads to the reorganization of the Na clusters in PbTe and their equilibration with the homogenized distribution of Na in the whole volume. The maximum ZT values of 1.4–1.6 at 760 K are established for both Pb1–xNaxTe and Pb1–yNayTe1–y/2 series. Upon long-time annealing at 873 K, reorganization and redistribution of N...

ConspectusMaterials with the crystal structure of γ-brass type (Cu5Zn8 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. The intermetallic compound Be21Pt5, a new member of this family, was synthesized, and its crystal structure, chemical bonding, and physical properties were characterized.Be21Pt5 crystallizes in the cubic space group F43m with lattice parameter a = 15.90417(3) A and 416 atoms per unit cell. From the crystallographic point of view, the binary substance represents a special family of intermetallic compounds called complex metallic alloys (CMA). The crystal structure was solved by a combination of synchrotron and neutron powder diffraction data. Besides the large difference in the scattering power of the components, the structure solution wa...

As one family of the most investigated thermoelectrics (TE), PbTe-based materials have been developed into state-of-the-art p-type and n-type TE materials. However, there are quite a few studies focusing on the reproducibility of TE properties and microstructure evolution during different heat treatments. In this work, Pb0.98−xNa0.02EuxTe (x = 0–0.030) samples were systematically examined after three different kinds of heat treatments: spark plasma sintering (SPS), laser flash measurement (LFA), and long-term annealing. The maximal solubility of Eu (ca. 1.0 atom%) in Pb0.98−xNa0.02EuxTe was established at 873 K. The most inhomogeneous samples (samples after SPS) show highest values of figure-of-merit, ZTmax, of up to 2.1 at 760 K, due to a large number of micrometer-scale sodium- and europium-rich aggregations in them. After additional heat treatment (LFA measurement or long-term annealing), the ZTmax value reduces to 1.6. The distribution of Eu and Na in the samples becomes much more homogeneous, accompanied by increased lattice parameters and decreased carrier concentrations. The long-term annealed samples have the best stable TE properties and good mechanical stability in the cyclic measurements. Surface protection needs to be considered for the temperatures above 773 K in order to avoid material decomposition.

This contribution presents the heat capacity of metastable Li15Si4 as a function of temperature in a range from (2 to 615) K. The measurements were performed using two different calorimeters depending on their specification. In the low temperature region from (2 to 300) K a calorimetric method based on a relaxation technique was used, whereas for the high temperature region from (300 to 615) K, DSC measurements applying the Cp-by-step method were carried out. The experimental data are given with an accuracy better than ±2% above 5 K and up to 9% below 5 K. The measurement at low temperatures allow the calculation of the standard entropy and entropy of formation as well as temperature coefficients of electronic and lattice contributions to the heat capacity. The results represent a significant contribution to the data basis for thermodynamic calculations (e.g. CALPHAD) and to the understanding of electrochemical equilibria in the Li-Si-system.

In this work we summarize a symbiotic approach to combine experimental and theoretical investigations for the derivation of high quality thermodynamic data for the description of potential lithium ion battery materials. The methodology of this concept was demonstrated in detail by exploring and describing the properties of the lithium monosilicide phase LiSi. The procedures were also applied in a series of investigations to all major LixSiy-phases which will be reviewed briefly. Regarding the LiSi phase, the measured and calculated isobaric heat capacity, which may enable further thermodynamic investigations (e. g. with CALPHAD method) of the phase diagram of the Li–Si-system is presented. The heat capacity of the stable phase LiSi was measured as a function of temperature in a range from (2 to 673) K and compared with corresponding ab-initio and molecular dynamic calculations resulting in values for absolute entropies. The heat of formation of the system was determined in an unconventional manner via hydrogenation experiments.

Single crystals of the compounds Li2 AeTt (Ae=Ca, Ba, Tt=Si, Ge, Sn, Pb) were grown in reactive lithium melts in sealed tantalum ampoules from an equimolar ratio of the alkaline earth metal and the respective group 4 element. All compounds, with the exception of Li2CaSn and Li2CaPb, are isotypic and crystallize in an orthorhombic unit cell (space group Pmmn, no. 59). The crystal structure can be characterized as superimposed corrugated networks of Li2 Tt connected by calcium or barium atoms within the third dimension. Li2CaSn and Li2CaPb crystallize in the cubic space group Fm3̅m (no. 225) in a Heusler-type (MnCu2Al) structure. According to magnetic susceptibility and electric resistivity measurements, the compounds Li2BaGe, Li2BaSn, and Li2BaPb represent diamagnetic activated semiconductors.

Large single crystals of Li2(Ca3N)2[Ga4] and Li2(Sr3N)2[Ga4] up to several mm in size were grown from mixtures of the respective elements and binary alkaline-earth metal nitrides in reactive lithium melts employing a modified high-temperature centrifugation-aided filtration (HTCAF) technique. The main structural features of these isotypic phases are stella quadrangula building units [Ga4]Li4/2 and octahedra (Nae6/2), which form two independent interpenetrating networks. The phases crystallize in the η-carbide structure and represent diamagnetic small bandgap semiconductors. Real-space chemical bonding analysis indicates predominantly ionic bonding.

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 Yb4Ga24Pt9 was determined from single-crystal X-ray diffraction data: new prototype of crystal structure, space group C2/m, Pearson symbol mS74, a = 7.4809(1) A, b = 12.9546(2) A, c = 13.2479(2) A, β = 100.879(1)°, V = 1260.82(6) A3, RF = 0.039 for 1781 observed reflections and 107 variable parameters. The structure is described as an ABABB stacking of two slabs with trigonal symmetry and compositions Yb4Ga6 (A) and Ga12Pt6 (B). The hard X-ray photoelectron spectrum (HAXPES) of Yb4Ga24Pt9 shows both Yb2+ and Yb3+ contributions as evidence of an intermediate valence state of ytterbium. The evaluated Yb valence of ∼2.5 is in good agreement with the results obtained from the magnetic susceptibility measurements. The compound is a bad metallic conductor.

The phase and chemical compositions of the mineral chalcopyrite from the sulfide footwall vein in La Cantera (Zacatecas, Mexico) is examined by powder X-ray diffraction, energy dispersive X-ray spectroscopy, and chemical ICP-OES analyses. The influence of the detected impurities on the thermoelectric parameters (i.e. thermopower, electrical and thermal conductivities) is discussed. Thermoelectric figure of merit, ZT, of the studied natural minerals is found to be of the same order of magnitude (ca. 10–3) as reported for CuFeS2 synthesized in the laboratory.

Na16Cs8Li x Ge136−x (x≈2.8, space group Fd3̅m) is the first intermetallic type-II clathrate with a lithium-substituted framework. The phase was obtained from the elements in sealed Ta ampoules by annealing at 650°C for 5 days. Samples were investigated by synchrotron X-ray powder diffraction, solid-state NMR, microstructure and chemical analysis. The substitution of Ge by Li atoms causes a marked shrinking of the lattice parameter. Studies by 7Li NMR confirmed the presence of Li in the clathrate phase and the 23Na and 133Cs NMR spectra consistently showed distinct changes as compared to the ternary Na16Cs8Ge136. The SEDOR technique revealed a distance between Li and Cs atoms in agreement with the result of crystal structure refinement, indicating Li substitution at site 96g. The distinct Knight shift of all NMR signals implies metallic behaviour of the clathrate phase, measurements of the magnetic susceptibility indicate diamagnetic behaviour.

The homogeneity range of ternary iron indium thiospinel at 873 K was investigated. A detailed study was focused on two distinct series (y=z): 1) a previously reported charge‐balanced (In0.67+0.33y□0.33−0.33y)tetr[In2−zFez]octS4 (A1‐series; □ stands for vacancy; the abbreviations “tetr” and “oct” indicate atoms occupying tetrahedral 8a and octahedral 16d sites, respectively) and 2) a new charge‐unbalanced (In0.67+y□0.33−y)tetr[In2−zFez]octS4 (A2‐series). Fe atoms were confirmed to exclusively occupy an octahedral position in both series. An unusual reduction of the unit cell parameter with increasing Fe content is explained by differences in the ionic radii between Fe and In, as well as by an additional electrostatic attraction originating from charge imbalance (latter only in A2‐series). The studied compound is an n‐type semiconductor, and its charge carrier concentration increases or decreases for larger Fe content within the A1‐ and A2‐series, respectively. The thermal conductivity κ tot is significantly reduced upon increasing vacancy concentration, whereas the change of power factor is insufficient to drastically improve the thermoelectric figure of merit., Iron indium thiospinel: Two different mechanisms for the Fe incorporation into indium thiospinel were investigated, namely the charge‐balanced (A1) and the charge‐unbalanced (A2) series. The Fe content (i.e., vacancy concentration) strongly influences the unit cell parameter, charge carrier concentration, charge carrier mobility, as well as thermal conductivity (κ tot) in both series.

We present the synthesis route to carbon with hierarchical morphology on the nanoscale. The structures are generated using crystalline orthorhombic lithium carbide (Li2C2) as precursor with nanolamellar organization. Careful treatment by SnI4 oxidizes carbon at the fairly low temperature of 80 °C to the elemental state and keeps intact the initial crystallite shape, the internal lamellar texture of particles, and the lamellae stacking. The reaction product is amorphous but displays in the microstructure parallel band-like arrangements with diameters in the range of 200–500 nm. These bands exhibit internal fine structure made up by thin strips of about 60 nm width running inclined with respect to the long axis of the band. The stripes of neighboring columns sometimes meet and give rise to arrow-like arrangements in the microstructure. This is an alternative preparation method of nanostructured carbon from an inorganic precursor by a chemical redox route without applying physical methods such as ion implant...

The unprecedented, fully deprotonated form of acetonitrile, the acetonitriletriide anion CCN3−, is experimentally realized for the first time in the stabilizing bulk host framework of the Ba5[TaN4][C2N] nitridometalate via a one-pot synthesis from the elements under moderate conditions (920 K). The molecular structure of this long-sought acetonitrile derivative is confirmed by X-ray diffraction, as well as NMR, IR, and Raman spectroscopy. The anion is isoelectronic to the CO2 molecule, and, in contrast to acetonitrile (H3C−C≡N), the electron pairs are shifted towards two double bonds, that is, [C=C=N]3−.

We explored the role of valence electron concentration in bond formation and superconductivity of mixed silicon–aluminum networks by using high-pressure synthesis to obtain the BaAl4-type structural pattern in solid solution samples SrAl4–xSix where 0 ≤ x ≤ 2. Local ordering of aluminum and silicon in SrAl4–xSix was evidenced by nuclear magnetic resonance experiments. Subsequent bonding analysis by quantum chemical techniques in real space demonstrated that the strong deviation of the lattice parameters in SrAl4–xSix from Vegard’s law can be attributed to the strengthening of interatomic Al–Al and Al–Si bonds within the layers (perpendicular to [001]) for 0 ≤ x ≤ 1.5, followed by the breaking of the interlayer bonds (parallel to [001]) for 1.5 < x ≤ 2 and leading to the structural transition from the BaAl4 structure type with three-dimensional anionic framework at lower x values to the two-dimensional anion of the BaZn2P2 structure type with increasing x values. Low-temperature measurements of the resisti...

The compounds MNi21B20 (M = In, Sn) have been synthesized and their cubic crystal structure determined (space group Pm[3 with combining macron]m, lattice parameters a = 7.1730(1) Å and a = 7.1834(1) Å, respectively). The structure can be described as a hierarchical partitioning of space based on a reo-e net formed by Ni3 species with large cubical, cuboctahedral and rhombicuboctahedral voids being filled according to [Ni1@Ni38], [M@Ni312], and [Ni26@B20@Ni324], respectively. The [Ni6@B20] motif inside the rhombicuboctahedral voids features an empty [Ni6] octahedron surrounded by a [B20] cage recently described in E2Ni21B20 (E = Zn, Ga). Position-space bonding analysis using ELI-D and QTAIM space partitioning as well as 2- and 3-center delocalization indices gives strong support to an alternative chemical description of space partitioning based on face-condensed [B@Ni6] trigonal prisms as basic building blocks. The shortest B–B contacts display locally nested 3-center B–B–Ni bonding inside each trigonal prism. This clearly rules out the notion of [Ni6@B20] clusters and leads to the arrangement of 20 face-condensed [B@Ni23Ni33] trigonal prisms resulting in a triple-shell like situation Ni26@B20@Ni324(reo-e), where the shells display comparable intra- and inter-shell bonding. Both compounds are Pauli paramagnets displaying metallic conductivity.

The intermetallic phase [Li x Ba8−x ][Li y Si46−y ] is the first example of a clathrate-I silicide containing lithium with the peculiarity that the Li atoms occupy both cage and framework positions. The phase was obtained by ambient-pressure solid-state reactions at 400°C between Ba4Li2Si6 and the binary clathrate phase Ba8−x Si46 applying different experimental approaches. In this reaction, Li atoms substitute Si atoms of the framework at site 6c (space group Pm3̅n) and fill up the Ba-deficient dodecahedral Si20 cages at site 2a. The presence of Li atoms in the clathrate phase was proven by combined X-ray powder diffraction, 7Li and 29Si solid-state NMR analyses. Incorporation of lithium markedly increased the lattice parameter of the clathrate phase, e.g. from a=10.3200(2) Å for Ba7.48(2)Si46 to a=10.3715(3) Å for [Li0.59(2)Ba7.41(2)][Li2.3(1)Si43.7(1)]. The critical temperature T c for the transition to the superconducting state decreased from 7.7 K to 3.2 K upon Li incorporation.

The crystal structures of the trigermanidesAEGe3(tI32) (AE= Ca, Sr, Ba; space groupI4/mmm, for SrGe3:a= 7.7873(1),c= 12.0622(3) Å) comprise Ge2dumbbells forming layered Ge substructures which enclose embeddedAEatoms. The chemical bonding analysis by application of the electron localizability approach reveals a substantial charge transfer from theAEatoms to the germanium substructure. The bonding within the dumbbells is of the covalent two-center type. A detailed analysis of SrGe3reveals that the interaction on the bond-opposite side of the Ge2groups is not lone pair-like – as it would be expected from the Zintl-like interpretation of the crystal structure with anionic Ge layers separated by alkaline-earth cations – but multi-center strongly polar between the Ge2dumbbells and the adjacent metal atoms. Similar atomic interactions are present in CaGe3and BaGe3. The variation of the alkaline-earth metal has a merely insignificant influence on the superconducting transition temperatures in thes,p-electron compoundsAEGe3.

We report the high-pressure high-temperature synthesis (P = 15 GPa, T = 1300 K) of BaGe3(tI32) adopting a CaGe3-type crystal structure. Bonding analysis reveals layers of covalently bonded germanium dumbbells being involved in multicenter Ba-Ge interactions. Physical measurements evidence metal-type electrical conductivity and a transition to a superconducting state at 6.5 K. Chemical bonding and physical properties of the new modification are discussed in comparison to the earlier described hexagonal form BaGe3(hP8) with a columnar arrangement of Ge3 triangles.

The combined powder X-ray diffraction, microstructural, local and bulk chemical analyses of natural pyrite single crystals from Reiche Zeche, Johangeorgenstadt and Pretzchendorf (Erzgebirge, Saxony, Germany) showed compositions FeAs0.002(1)S1.998(9), FeAs0.004(1)S1.996(9) and FeAs0.005(1)S1.995(9), respectively. The arsenic doping leads to smaller semiconducting energy gaps (Eg ~0.1–0.2 eV) in comparison with binary FeS2 (Eg = 0.96 eV), as well as switching of conduction type mechanism from n-to the p-type. These findings are supported by the measurements of the electrical resistivity and Seebeck coefficient of the synthetic FeAsxS2-x series (maximal As-content x = 0.01 at 773 K). The investigations of sintered FeS2 + MO2 (M = Si, Ti, Zr) composites indicate that some insulating metal oxides as impurities influence less the electrical transport properties of pyrite. All performed studies unambiguously confirmed that p-type conductivity for T > 300 K is a hallmark of the ternary As-doped FeAsxS2-x (x ≥ 0.002) pyrites.

${\mathrm{LaPtGe}}_{3}$ and ${\mathrm{CePtGe}}_{3}$ crystallize with a noncentrosymmetric body-centered tetragonal (space group $I4mm$)$\phantom{\rule{4pt}{0ex}}{\mathrm{BaNiSn}}_{3}$-type of structure. ${\mathrm{LaPtGe}}_{3}$ is a weakly coupled BCS-like $s$-wave type-I superconductor with ${T}_{\mathrm{c}}=0.55$ K, ${B}_{\mathrm{c}}\ensuremath{\simeq}14$ mT, and Ginzburg-Landau parameter ${\ensuremath{\kappa}}_{\mathrm{GL}}=0.021l1/\sqrt{2}$. ${\mathrm{CePtGe}}_{3}$ is a nonsuperconducting (${T}_{\mathrm{nsc}}=0.35$ K) metal with an effective magnetic moment ${\ensuremath{\mu}}_{\mathrm{eff}}=2.46{\ensuremath{\mu}}_{\mathrm{B}}$. The Ce moments show two antiferromagnetic ordering transitions at ${T}_{\mathrm{N}1}\ensuremath{\approx}3.7$ K and ${T}_{\mathrm{N}2}\ensuremath{\approx}2.7$ K and a ground-state multiplet $J=5/2$ splitting into three doublets (energy splittings from the ground state ${\mathrm{\ensuremath{\Delta}}}_{1}=46$ K and ${\mathrm{\ensuremath{\Delta}}}_{2}=137$ K). The moderately enhanced Sommerfeld coefficient ${\ensuremath{\gamma}}_{0}$ and the observation of almost the full critical magnetic entropy at ${T}_{\mathrm{N}1}$ suggest that magnetic Ruderman-Kittel-Kasuya-Yosida-type interactions are dominant in ${\mathrm{CePtGe}}_{3}$, leading to a magnetically ordered ground state.

Polycrystalline samples of the solid solution Pb1−xEuxTe were prepared by the spark-plasma technique. In contrast to the literature data, the homogeneity range of the solid solution amounts only to 0 ≤ x ≤ 0.02 under the selected preparation conditions. The implementation of Eu into the PbTe lattice was monitored by refinement of the lattice parameters. The thermoelectric properties of the prepared materials were investigated above room temperature. In samples with compositions x ≤ 0.04, the solid solution Pb1−xEuxTe reveals a metal–semiconductor transition around 500 K going in parallel to the p–n transition in the conductivity. No significant influence of the europium substitution on the thermoelectric figure-of-merit was observed in stoichiometric bulk materials. Introduction to the international collaboration Collaboration between Prof. Yuri Grin's group at Max-Planck Institute of Chemical Physics of Solids and Prof. Jing-Tai Zhao's group at Shanghai University (at Shanghai Institute of Ceramics, Chinese Academy of Sciences before 2014) in the field of Solid State Chemistry and Physics of intermetallic compounds started from 1999 followed by an establishment of a Partner Group between the Max-Planck Society and Chinese Academy of Sciences. The collaboration is highly recognized, in particular the studies on exploration of novel high-performance thermoelectric materials – so-called “122” Zintl phases – in pnictide systems and germanium clathrates. The long-term collaboration generated more than 30 joint publications in international journals and many presentations at national and international conferences, more than 10 co-supervised students and postdocs, and a series of workshops on X-ray Crystallography in Shanghai and Dresden.

A new intermetallic compound AlPd15B7 was synthesized by arc-melting the stoichiometric mixture of the elements. Single crystal X-ray diffraction data of ternary metal-rich boride reveal a new type of structure with the space group Ia3d and the lattice parameter a = 16.4466(3) Å. It adopts a filled anti-Yb3Rh4Sn13-type structure, where the positions corresponding to 3Yb, 4Rh and 13Sn atoms are occupied by 3Pd, 4B, and 1Al + 12 Pd, respectively and 3B additionally at interstitial sites. Magnetic susceptibility, electrical resistivity, and specific heat measurements reveal bulk superconductivity with a critical temperature Tc ≈ 2.9 K. Electronic structure calculations show that Pd 4d and B 2p states dominate the density of states (DOS) at the Fermi level EF.

Mixed spin-singlet and spin-triplet pairing can occur in noncentrosymmetric superconductors. In this respect, a comprehensive characterization of the noncentrosymmetric superconductor BeAu was carried out. It was established that BeAu undergoes a structural phase transition from a low-temperature noncentrosymmetric FeSi structure type to a high-temperature centrosymmetric structure in the CsCl type at ${T}_{\text{s}}=860$ K. The low-temperature modification exhibits a superconducting transition below ${T}_{\text{c}}=3.3$ K. The values of lower (${H}_{\text{c1}}=32$ Oe) and upper (${H}_{\text{c2}}=335$ Oe) critical fields are rather small, confirming that this type-II (${\ensuremath{\kappa}}_{\text{G-L}}=2.3$) weakly coupled (${\ensuremath{\lambda}}_{\text{e-p}}=0.5,\phantom{\rule{0.28em}{0ex}}\mathrm{\ensuremath{\Delta}}{C}_{\text{e}}/{\ensuremath{\gamma}}_{\text{n}}{T}_{\text{c}}\ensuremath{\approx}1.26$) superconductor can be well understood within the Bardeen-Cooper-Schrieffer theory. The muon spin relaxation analysis indicates that the time-reversal symmetry is preserved when the superconducting state is entered, supporting conventional superconductivity in BeAu. From the density functional band structure calculations, a considerable contribution of the Be electrons to the superconducting state was established. On average, a rather small mass renormalization was found, consistent with the experimental data.

Unusual physical properties like large magnetoresistance (MR) and superconductivity occurring in semimetals with Dirac or Weyl points are often linked to their topologically nontrivial band structures. However, there is an increasing number of reports on semimetals that show large MR in the absence of Dirac or Weyl points. Herein we report an experimental and theoretical study on the layered transition-metal dichalcogenide (TMDC) $\mathrm{HfT}{\mathrm{e}}_{2}$ that shows a large MR of $1350%$ at $T=2$ K and ${\ensuremath{\mu}}_{0}H=9\phantom{\rule{0.16em}{0ex}}\mathrm{T}$ in the absence of Dirac or Weyl points. Moreover, the structure and electrical resistivity under pressure reveal a unique structural transition. These results clearly distinguish $\mathrm{HfT}{\mathrm{e}}_{2}$ from TMDCs like $\mathrm{MoT}{\mathrm{e}}_{2}$ or $\mathrm{WT}{\mathrm{e}}_{2}$ which both exhibit larger MR and are viewed as Weyl semimetals. $\mathrm{HfT}{\mathrm{e}}_{2}$ is an appealing platform for future investigations on the interplay of particular band-structure features and their connection to emerging physical properties.

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. Analysis of the chemical bonding with position-space techniques discloses multicenter interactions within the Bi-Cu-Bi slabs and lone-pair interactions of the van der Waals type between these entities. hp-CuBi exhibits metal-type electrical conductivity with superconductivity below Tc =1.3 K.

The superconducting properties of [Formula: see text]Mo6S8 [[Formula: see text]] Chevrel phase [[Formula: see text] K] are studied on a sample compacted by spark plasma sintering. Both lower ([Formula: see text] mT) and the upper [[Formula: see text] T] critical magnetic fields are obtained from magnetization and electrical resistivity measurements for the first time. The analysis of the low-temperature electronic specific heat indicates [Formula: see text]Mo6S8 to be a two band superconductor with the energy gaps [Formula: see text] meV (95%) and [Formula: see text] meV (5%). Theoretical DFT calculations reveal a much stronger electron-phonon coupling in the studied Chevrel phase compared to earlier reports. Similar to MgB2, the Fermi surface of studied Chevrel phase is formed by two hole-like and one electron-like bands.

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 I 4 &macr, 2m (no. 121) and adopts a unique atomic arrangement which is a distorted variant of the CaGe3 type. At ambient pressure and 570(5) K, the compound decomposes in an exothermal reaction into (hP3)BaSi2 and two amorphous silicon-rich phases. Chemical bonding analysis reveals covalent bonding in the silicon partial structure and polar multicenter interactions between the silicon layers and the barium atoms. The temperature dependence of electrical resistivity and magnetic susceptibility measurements indicate metallic behavior.

The mixed-valent nitridomanganate Ba4[Mn3N6] was prepared using a gas–solid high temperature route. The crystal structure was determined employing high resolution synchrotron powder diffraction data: space group Pbcn, a = 9.9930(1) Å, b = 6.17126(8) Å, c = 14.4692(2) Å, V = 892.31(2) Å3, Z = 4. The manganese atoms in the structure of Ba4[Mn3N6] are four-fold coordinated by nitrogen forming infinite corrugated chains of edge-sharing [MnN4] tetrahedra. The chains demonstrate a complete charge order of Mn species. Magnetization measurements and first principle calculations indicate quasi-one dimensional magnetic behavior. In addition, chemical bonding analysis revealed pronounced Mn–Mn interactions along the chains.

We present a detailed study of $^{75}\text{A}\text{s}$ nuclear magnetic resonance Knight shift and spin-lattice relaxation rate in the normal state of stoichiometric polycrystalline LiFeAs. Our analysis of the Korringa relation suggests that LiFeAs exhibits strong antiferromagnetic fluctuations, if transferred hyperfine coupling is a dominant interaction between $^{75}\text{A}\text{s}$ nuclei and Fe electronic spins, whereas for an on-site hyperfine coupling scenario, these are weaker, but still present to account for our experimental observations. Density-functional calculations of electric field gradient correctly reproduce the experimental values for both $^{75}\text{A}\text{s}$ and $^{7}\text{L}\text{i}$ sites.