Luyang Chen

A low temperature synthesis of crystalline B4C ultrafine powders

Abstract B 4 C ultrafine powders were successfully synthesized at 450 °C through a new co-reduction route. The synthesis was carried out in an autoclave by using BBr 3 and CCl 4 as the reactants and metallic Na as the co-reductant. The X-ray powder diffraction pattern and Raman spectra indicate the formation of B 4 C. An atomic ratio of B to C of 4.09:1.0 was determined from X-ray photoelectron spectra. Transmission electron microscopy images shows that typical B 4 C crystallites are composed of uniform ultrafine spherical and rod-like particles.

A co-reduction synthesis of superconducting NbC nanorods

NbC nanorods with diameters of 50–150 nm were successfully synthesized through a new chemical route by using NbCl5 and hexachlorobutadiene (C4Cl6) as Nb and C sources, and Na metal as the reductant at 600 °C in an autoclave. This reaction temperature is much lower than that used in traditional methods. The as-prepared NbC nanorods were characterized by x-ray powder diffraction, transmission electron microscopy and x-ray photoelectron spectra. Magnetization measurement indicated that the NbC nanorods have a superconducting transition at 12.3 K.

Paramagnetic ground state with field-induced partial order in Nd3Ga5SiO14 probed by low-temperature heat transport

We study the low-temperature heat transport of Nd_3Ga_5SiO_{14}, which is a spin-liquid candidate, to probe the nature of ground state and the effect of magnetic field on the magnetic properties. The thermal conductivity (\kappa) shows a purely phononic transport in zero field. The external magnetic field along the c axis induces a dip-like behavior of \kappa(H), which can be attributed to a simple paramagnetic scattering on phonons. However, the magnetic field along the ab plane induces another step-like decrease of \kappa. This kind of \kappa(H) behavior is discussed to be related to a field-induced partial order, which yields low-energy magnetic excitations that significantly scatter phonons. These results point to a paramagnetic ground state that partial magnetic order can be induced by magnetic field along the ab plane, which is also signified by the low-T specific heat data.

Low-temperature heat transport of Nd2CuO4: Roles of Nd magnons and spin-structure transitions

We report the magnetic-field dependence of thermal conductivity (\kappa) of an insulating cuprate Nd_2CuO_4 at very low temperatures down to 0.3 K. It is found that apart from the paramagnetic moments scattering on phonons, the Nd^{3+} magnons can act as either heat carriers or phonon scatterers, which strongly depends on the long-range antiferromagnetic transition and the field-induced transitions of spin structure. In particular, the Nd^{3+} magnons can effectively transport heat in the spin-flopped state of the Nd^{3+} sublattice. However, both the magnon transport and the magnetic scattering are quenched at very high fields. The spin re-orientations under the in-plane field can be conjectured from the detailed field dependence of \kappa.

Low-temperature heat transport in the layered spin-dimer compound Ba 3 Mn 2 O 8

We report a study on the low-temperature heat transport of the Ba

Pt nanoparticles deposited over carbon nanotubes for selective hydrogenation of cinnamaldehyde

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Preparation and some properties of nanocrystalline ZrB2 powders

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A hydrothermal method to prepare the spherical ZnS and flower-like CdS microcrystallites

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Synthesis and morphology control of nanocrystalline boron nitride

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Solvothermal preparation of amorphous carbon nanotubes and Fe/C coaxial nanocables from sulfur, ferrocene, and benzene

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