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The three-dimensional atomic configuration of amorphous Ge 2 Sb 2 Te 5 and GeTe were derived by reverse Monte Carlo simulation with synchrotron-radiation x-ray diffraction data. The authors found that amorphous Ge 2 Sb 2 Te 5 can be regarded as "even-numbered ring structure," because the ring statistics is dominated by four-and six-fold rings analogous to the crystal phase. On the other hand, the formation of Ge-Ge homopolar bonds in amorphous GeTe constructs both odd-and even-numbered rings. They believe that the unusual ring statistics of amorphous Ge 2 Sb 2 Te 5 is the key for the fast crystallization speed of the material.

We present elastic and quasielastic neutron scattering measurements characterizing peculiar short-range charge-orbital and spin order in the layered perovskite material La1.5Sr0.5CoO4. We find that below T(c) approximately 750 K holes introduced by Sr doping lose mobility and enter a statically ordered charge glass phase with loosely correlated checkerboard arrangement of empty and occupied d(3z(2)-r(2)) orbitals ( Co3+ and Co2+). The dynamics of the resultant mixed spin system is governed by the anisotropic nature of the crystal-field Hamiltonian and the peculiar exchange pattern produced by the orbital order. It undergoes a spin freezing transition at a much lower temperature, T(s) less, similar30 K.

A thin film of sodium manganese ferrocyanide, Na1.32Mn[Fe(CN)6]0.83·3.5H2O, exhibits discharge capacity (= 109 mA h g(-1)) and discharge voltage (3.4 V in average) at 0.5 C against Na in aprotic solvent. The ex situ XRD experiments reveal that the host framework remains cubic without showing any structural phase transition during the charge process. The discharge property is discernible up to 40 C.

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The silicon clathrates--materials composed of metal-doped Si(20) dodecahedra--were identified as the first superconductors based on pure silicon networks. The mechanism of superconductivity in these materials can be obtained by studying their phonon modes, as modified by isotope substitution, and specific-heat measurements. Here, we present experimental studies that provide strong evidence that superconductivity in Ba(8)Si(46) is explained in the framework of phonon-mediated Bardeen-Cooper-Schriefer theory. Analyses using the McMillan approximation of the Eliashberg equation indicate that the superconducting mechanism is in the medium coupling regime, but at the high-end limit. The large density of states at the Fermi level, which arises from hybridization of the Si(20) cluster and Ba orbitals, is responsible for the unexpectedly high superconducting temperature. The temperature evolution of the specific heat unambiguously shows that this is an s-wave symmetry superconductor.