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We report robust superconducting state and gap symmetry of Nb5Ir3O via electrical transport and specific heat measurements. The analysis of specific heat manifests that Nb5Ir3O is a strongly coupled superconductor with and double s-wave superconducting gaps of and accounting for 90% and 10%, respectively. The vs. T plot shows a broad peak at ∼23 K, indicating phonon softening and the appearance of low-lying phonon mode associated with the interstitial oxygen. This behavior explains the monotonic increase of Tc in by strengthening the electron–phonon coupling and enlarging the density of states at Fermi level. The Hall coefficient is temperature independent below 200 K, and changes its sign from positive to negative above 250 K, suggesting that carrier is across the hole- to electron-dominant regions and the multi-band electronic structures. On warming, the resistivity shows a gradual crossover from - to -dependence at a critical temperature , and a broad peak at a temperature Tp. The reduced Tc under pressure is linearly correlated with lattice parameters c/a ratio and Tp, suggesting the important phonon contributions in Nb5Ir3O as a phonon-medicated superconductor. Possible physical mechanisms are proposed. [ABSTRACT FROM AUTHOR]

The new quaternary hydride EuNi5InH1.5 has been obtained by hydrogenation of the intermetallic parent EuNi5In under extremely mild conditions, hence, at room temperature and low hydrogen pressure. Hydrogenation at slightly elevated temperatures and pressures allows for the growth of large crystals, which is a rare observation for intermetallic hydrides. EuNi5InH1.5 crystallizes in its own structure type (hP17, P6̅m2, a = 4.9437(6), c = 10.643(1) Å) with a unique arrangement of the intermetallic host. The hydrogen atoms prefer Ni-surrounded positions, occupying {EuNi3} and {Eu2Ni2} tetrahedral voids in the structure. Upon hydrogenation of EuNi5In an anisotropic volume expansion accompanied with a decrease of symmetry is observed. Magnetic measurements reveal antiferromagnetic ordering in the hydride below 4 K and indicate an intermediate +II/+III oxidation state for Eu both in the intermetallic phase and the hydride. X-ray photoemission spectroscopy confirms the existence of the two different oxidation states of Eu. The hydrogenation does not affect the oxidation state of Eu and the type of magnetic ordering, but exerts a strong influence on the transition temperature, crystal structure, mechanical and electrical properties. Crystallographic analysis suggests that Eu(ii) and Eu(iii) do not order but rather mix homogeneously on crystallographic sites. Electronic structure calculations reveal the metallic character of the hydride with several different types of chemical bonding interactions being present in the compound ranging from the formally ionic Eu–H to covalent Ni–H and delocalized metal–metal. Geometry optimization confirm the thermodynamic instability of the intermetallic host lattice for the hydride and supports a transformation into the parental structure as observed experimentally. [ABSTRACT FROM AUTHOR]

Spin-polarization calculations of the electronic structure of intermetallic compounds DyNiCu ( x = 0, 1, 2) are performed in the local spin density approximation with strong electron correlations in the 4 f shell of a rare-earth ion taken into account (the LSDA + U). Spectral properties of these materials are studied by the optical ellipsometry method in the wavelength range of 0.22-16 μm. It is established that the optical absorption spectra are significantly modified upon partial substitution of nickel by copper atoms. The experimental dispersion dependences of optical conductivity in the region of interband light absorption are interpreted on the basis of calculations of electronic state densities. [ABSTRACT FROM AUTHOR]

A series of RENi9In2 compounds ( RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) and their hydrides, RENi9In2H x ( RE = La, Ce, Pr, Nd and Eu), have been synthesized and characterized using X-ray powder diffraction and magnetization measurements. All studied compounds adopt the YNi9In2 structure type [space group (SG) P4/ mbm]. The lattice parameters decrease from La to Er in accordance with the lanthanide contraction. Their structure can be visualized as a packing of rare-earth 20-vertices polyhedra and Ni-centred icosahedra in an AuCu-like arrangement. The hydrogenation results in the formation of RENi9In2H x with slightly expanded unit cells within the YNi9In2 structure type. Possible hydrogen positions in EuNi9In2H3.4 are proposed. Most of the compounds and their hydrides (with Pr and Nd) exhibit Curie-Weiss behaviour. No magnetic ordering could be detected down to T = 2 K. EuNi9In2 reveals ferromagnetism below approximately 40 K, which might be due to a secondary phase. Its hydride is Pauli paramagnetic, thus indicating the Eu3+ state. YNi9In2 and LaNi9In2 are Pauli paramagnets. The studied phases are typical metallic conductors. [ABSTRACT FROM AUTHOR]