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Polycrystalline LiGa2Ir has been prepared by a solid state reaction method. A Rietveld refinement of powder x-ray diffraction data confirms a previously reported Heusler-type crystal structure (space group Fm-3m, No. 225) with lattice parameter a = 6.0322(1) Å. The normal and superconducting state properties were studied by magnetic susceptibility, heat capacity, and electrical resistivity techniques. A bulk superconductivity with Tc = 2.94 K was confirmed by detailed heat capacity studies. The measurements indicate that LiGa2Ir is a weak-coupling type-II superconductor (λ e–p = 0.57, Δ C/ γ Tc = 1.4). Electronic structure, lattice dynamics, and the electron–phonon interaction are studied from first principles calculations. Ir and two Ga atoms equally contribute to the Fermi surface with a minor contribution from Li. The phonon spectrum contains separated high frequency Li modes, which are seen clearly as an Einstein-like contribution in the specific heat. The calculated electron–phonon coupling constant λ e–p = 0.68 confirms the electron–phonon mechanism for the superconductivity. LiGa2Ir and recently reported isoelectronic LiGa2Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC = 16. [ABSTRACT FROM AUTHOR]

Superconductivity was first observed more than a century ago, but the search for new superconducting materials remains a challenge. The Cooper pairs in superconductors are ideal embodiments of quantum entanglement. Thus, novel superconductors can be critical for both learning about electronic systems in condensed matter and for possible application in future quantum technologies. Here two previously unreported materials, NbIr2B2 and TaIr2B2, are presented with superconducting transitions at 7.2 and 5.2 K, respectively. They display a unique noncentrosymmetric crystal structure, and for both compounds the magnetic field that destroys the superconductivity at 0 K exceeds one of the fundamental characteristics of conventional superconductors (the "Pauli limit"), suggesting that the superconductivity may be unconventional. Supporting this experimentally based deduction, first‐principle calculations show a spin‐split Fermi surface due to the presence of strong spin–orbit coupling. These materials may thus provide an excellent platform for the study of unconventional superconductivity in intermetallic compounds. [ABSTRACT FROM AUTHOR]

We report the experimental and theoretical investigation of structure, chemical bonding interactions, and physical properties of new ternary stannides AIrSn2 (A = Sr and Ba). AIrSn2 (A = Sr and Ba) crystallizes in the orthorhombic Re3B-type structure with the space group Cmcm (No. 64). According to single-crystal X-ray diffraction results, the structure of AIrSn2 (A = Sr and Ba) can be considered as a Zintl-type compound with heterogeneous polyanionic [IrSn2]2− and A2+. The specific heat down to 1.8 K shows no evidence for bulk superconductivity in either SrIrSn2 or BaIrSn2. Electronic structure calculations, especially chemical bonding interactions in SrIrSn2 and BaIrSn2, match well with the observed structural stability and metallic nature. [ABSTRACT FROM AUTHOR]

Polycrystalline samples of Ho T 2 Al 20 ( T = Ti, V, Cr) intermetallics were synthesized using a step-wise arc-melting technique. All three compounds adopt the CeCr 2 Al 20 -type crystal structure with Ho atoms positioned inside oversized icosahedral cages formed by Al atoms. The structure of HoV 2 Al 20 compound is reported. The materials properties were studied by means of electrical resistivity, magnetic susceptibility, and specific heat measurements. All three compounds show a Curie-Weiss paramagnetic behavior down to 1.95 K. Specific heat measurements show the presence of electronic Schottky anomaly resulting from crystal-field splitting of Ho 3+ energy levels in the three compounds, while in HoTi 2 Al 20 and HoV 2 Al 20 a second anomaly was observed, resulting from the presence of low-energy Einstein phonon mode. [ABSTRACT FROM AUTHOR]

Single crystals of a new ternary aluminide ErV 2 Al 20 were grown using a self-flux method. The crystal structure was determined by powder X-ray diffraction measurements and Rietveld refinement, and physical properties were studied by means of electrical resistivity, magnetic susceptibility and specific heat measurements. These measurements reveal that ErV 2 Al 20 is a Curie-Weiss paramagnet down to 1.95 K with an effective magnetic moment μ eff =9.27(1) μ B and Curie-Weiss temperature Θ CW =−0.55(4) K. The heat capacity measurements show a broad anomaly at low temperatures that is attributed to the presence of a low-energy Einstein mode with characteristic temperature Θ E =44 K, approximately twice as high as in the isostructural ‘Einstein solid’ VAl 10.1 . [ABSTRACT FROM AUTHOR]

Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single-crystal X-ray data to be isotypic with the ThB2C-type (space group,a= 0.6532(2) nm;c= 1.0769(3) nm for NpB2C anda= 0.6509(2) nm;c= 1.0818(3) nm for PuB2C;Z= 9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C with a Neel temperatureTN= 68 K. PuB2C is a Pauli paramagnet most likely due to a strong hybridization of s(p,d) electrons with the Pu-5fstates. A pseudo-gap, as concluded from the Sommerfeld value and the electronic transport, is thought to be a consequence of the hybridization. The magnetic behaviour of {Np,Pu}B2C is consistent with the criterion of Hill. [ABSTRACT FROM PUBLISHER]

Abstract The synthesis, structure and elementary magnetic characterization of the homometallic warwickite V 2 OBO 3 are reported. The material adopts the orthorhombic warwickite structure type at room temperature, space group Pnma (No. 62) with lattice parameters a = 9.2317(1) Å, b = 3.1172(1) Å, and c = 9.5313(1) Å. Temperature-dependent magnetic susceptibility, electrical resistivity, and specific heat measurements show anomalies near 35 K, between 135 K and 150 K, and near 260 K, with the transition at ~ 35 K likely to a ferrimagnetic state. High resolution synchrotron powder X-ray diffraction data at temperatures between 295 K and 90 K display significant peak splitting upon cooling, indicating that at least one crystallographic symmetry change occurs at low temperatures. Graphical abstract Crystal structure of homometallic warwickite V 2 OBO 3 at ambient temperature, viewed down the b -direction (left), looking down on the ribbons made from edge-sharing VO 6 octahedra. The trigonal planar BO 3 groups are also shown. The octahedra share edges in the ribbons (top right). Vanadium is shown in blue (inside the orange octahedra), boron in grey, and oxygen in red. An isolated set of V2-V1-V1-V2 –oxygen octahedra in the width of the ribbon, with all atoms labeled, is also shown (bottom right). fx1 Highlights • New mixed valent vanadium borate. • Multiple phase transitions on cooling. • High resolution synchrotron powder X-ray diffraction data. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 /SrTiO 3 _BiOI samples have been synthesized using multistep preparation method. • The heterostructures exhibited excellent photocatalytic activity under Vis light. • Obtained heterojunction can reduce the recombination of photogenerated electrons. • The charge transfer process and mechanism for phenol degradation were proposed. A series of binary TiO 2 /SrTiO 3 and ternary TiO 2 /SrTiO 3 _BiOI composites have been synthesized using multistep preparation method. Characterization of the obtained photocatalysts covered complex analysis including morphology + y (SEM), BET specific surface area, porosity, optical properties (DRS), chemical composition of surface (XPS), crystal structure and crystal size (XRD). UV–vis and Vis ligh induced photocatalytic activity was investigated in the model reaction of phenol degradation in the aqueous phase. The powder TiO 2 /SrTiO 3 _BiOI ternary composites exhibited a new photocatalytic properties and could be used in the heterogeneous photocatalysis processes. The photocatalytic activity observed in the phenol degradation reaction significantly increased under the visible light range irradiation. The best photocatalytic activity was observed for the TiO 2 /SrTiO 3 _BiOI_4 sample, about 30.2 % of phenol was decomposed after 1 h of visible light irradiation. The utilization of the nanolayered materials facilitates the separation of photocatalysts from the aqueous phase. Moreover, the composite was easily reused without the significant decrease of the photocatalytic activity in three subsequent cycles. After 5 h of Vis irradiation of the isotopically labeled (1-13C) phenol solution in the presence of the TiO 2 /SrTiO 3 _BiOI_4 composite, the salicylic, maleic, fumaric and malonic acids were detected using GC–MS equipment. The identification of degradation by-products led to clarification of phenol decomposition pathway. The role of active species during the decomposition process of organic compound was investigated using different types of active species scavengers. [ABSTRACT FROM AUTHOR]

The article presents a study on two new superconductors or chiral noncentrosymmetric superconducting materials that have chiral crystal structures in addition to having noncentrosymmetric crystal structures. According to the study, the impact of chirality on the properties of superconductors and devices that incorporate them is revealed in the analysis of superconducting materials.

• The polycrystalline sample of the new compound La 15 MoGe 9 was synthesized. • La 15 MoGe 9 crystallizes in a new version of Mn 5 Si 3 -type structure. • La 15 MoGe 9 is the first compound in ternary system La-Mo-Ge. • The specific heat measurement shows no phase transition down to 2 K. We present the synthesis, structural characterization and physical properties measurements of a new compound, La 15 Mo x Ge 9 in Mn 5 Si 3 -type derived structure with interstitial Mo. The sample was synthesized by arc-melting method. La 15 Mo x Ge 9 crystallizes in non-centrosymmetric hexagonal structure P 6 3 mc (#186) with lattice parameters a = b = 15.495(5) Å and c = 6.917(2) Å. The refinement on single X-ray diffraction data show that interstitial atom Mo occupies two different Wyckoff positions (2 a , 2 b) with 0.19(2) Mo/per f.u. The specific heat properties were well studied. The obtained Sommerfeld coefficient and Debye temperature are: γ = 89.2(9) mJ/(mol K2) and Θ D = 190(5) K, respectively. La 15 Mo x Ge 9 is the first compound in the ternary system La-Mo-Ge. [ABSTRACT FROM AUTHOR]

Single crystals of completely ordered variant of the YNi 3 Al 9 compound were grown by self-flux method with excess of aluminum. The crystal structure of the title compound was redetermined from single crystal X-ray diffraction data. The structure adopts ErNi 3 Al 9 type, space group R32 , parameters of the unit cell a ​= ​7.2838(2) Å, c ​= ​27.4004(8) Å. The growth of relatively large single crystals of the YNi 3 Al 9 compound, having completely ordered structure, indicates possible existence of region on phase diagram, where the title compound is in equilibrium with liquid. Comparison with the results in the literature on the investigations of the same and related compounds shows trend towards formation of more ordered structures in flux grown samples and more disordered ones in arc melted samples. Physical properties of the title compound - electrical resistivity, magnetoresistance and heat capacity - were measured for the first time. It shows metallic-like behavior with very high values of magnetoresistance up to 420% at low temperatures without presence of magnetic elements. Therefore electronic structure calculations were carried out. The phonon heat capacity reveals major Debye and minor Einstein contributions at the intermediate temperatures, and total heat capacity approaches Dulong-Petit limit at high temperatures. The calculated Debye temperature from the whole temperature range θ D ​= ​480(6) K is typical for aluminium-rich compounds. Corresponding Einstein temperature is θ E ​= ​198(8) K. The estimations of electron-phonon coupling constant λ ​= ​0.092 show very weak coupling and absence of superconducting transition. YNi 3 Al 9 : structure and magnetoresistance. [Display omitted] • Completely ordered sample of the YNi 3 Al 9 compound obtained by self-flux method. • Its structure redetermined using single crystal diffraction data. • Physical properties of the YNi 3 Al 9 compound investigated for the first time. • Electrical resistivity, magnetoresistance and heat capacity were measured. • Very high values of magnetoresistance up to 420% are observed at low temperatures. [ABSTRACT FROM AUTHOR]

TiO 2 (P25) was modified with small and relatively monodisperse mono- and bimetallic clusters (Ag, Pd, Pt, Ag/Pd, Ag/Pt and Pd/Pt) induced by radiolysis to improve its photocatalytic activity. The as-prepared samples were characterized by X-ray fluorescence spectrometry (XRF), photoluminescence spectrometry (PL), diffuse reflectance spectroscopy (DRS), X-ray powder diffractometry (XRD), scanning transition electron microscopy (STEM) and BET surface area analysis. The effect of metal type (mono- and bimetallic modification) as well as deposition method (simultaneous or subsequent deposition of two metals) on the photocatalytic activity in toluene removal in gas phase under UV–vis irradiation (light-emitting diodes- LEDs) and phenol degradation in liquid phase under visible light irradiation (λ > 420 nm) were investigated. The highest photoactivity under Vis light was observed for TiO 2 co-loaded with platinum (0.1%) and palladium (0.1%) clusters. Simultaneous addition of metal precursors results in formation of larger metal nanoparticles (15–30 nm) on TiO 2 surface and enhances the Vis-induced activity of Ag/Pd-TiO 2 up to four times, while the subsequent metal ions addition results in formation of metal particle size ranging from 4 to 20 nm. Subsequent addition of metal precursors results in formation of BNPs (bimetallic nanoparticle) composites showing higher stability in four cycles of toluene degradation under UV–vis. Obtained results indicated that direct electron transfer from the BNPs to the conduction band of the semiconductor is responsible for visible light photoactivity, whereas superoxide radicals (such as O 2 − and OOH) are responsible for pollutants degradation over metal-TiO 2 composites. [ABSTRACT FROM AUTHOR]

Surface distribution of quantum dots (QDs) at the semiconductor matrix caused by synthesis condition (e.g. pH of solution during coupling) could lead to different photocatalytic activity. Thus, achieving an optimal covering of semiconductor matrix by QDs has been challenging. Herein, the influence of the alkalinity level of aqueous decoration medium for the coupling of mercaptoundecanoic acid (MUA) capped CuInS 2 quantum dots (CIS) and ZnIn 2 S 4 microspheres (ZIS) on photocatalytic hydrogen evolution (PHE) performance was investigated. Aqueous decoration medium with different alkalinity levels for the formation of ZIS/CIS photocatalytic system resulted in significantly different PHE performances in the presence of (0.5 wt%) Pt co-catalyst deposition without any change in crystal structure of ZIS matrix up to pH 12.5. The photocatalytic system obtained at pH 10.5 possessed the highest performance followed by the decrease at pH 11.5 and again the remarkable increase was detected at pH 12.5 that was the pH level for uniform dispersion of CIS in aqueous medium. This work remarks the importance of the nanoparticle's aggregates on PHE performance over non-toxic ZnIn 2 S 4 /CuInS 2 photocatalytic system. [Display omitted] [ABSTRACT FROM AUTHOR]