Effective control of carbon concentration in a crystal is required for the production of a high-quality crystal. We proposed an improved unidirectional solidification furnace to produce crystals with lower carbon concentration. The global simulation of coupled oxygen and carbon transports within this furnace was used to validate the feasibility of its improved design.
We held the workshop on the 3D imaging of atoms, based on holography and phase retrieval methods of X-ray, electron and neutron scatterings. Topics on electron and X-ray emission holography, surface (interface) scattering holography, and coherent electron and X-ray diffractive imaging methods were intensively discussed during the workshop. Toward examining middle range local structures of materials contributable to green and life sciences, we set a new goal for the improvements of these methods.
The effect of defects on the electronic structures of type-VIII Ba8Ga16Sn30 (BGS) clathrates, promising thermoelectric materials, has been investigated by ab initio electronic structure calculations. The solid and dotted curves denote the band structures near the band gap of BGS with and without defects, respectively. The defects change notably the valence bands, but little the conduction bands. This is in good agreement with experimental results of carrier properties of BGS.
Magnetic fluctuations of Fe1+xSe0.45Te0.55 (x = 0, δ) are investigated by using neutron scattering technique. Non-superconducting Fe1+δSe0.45Te0.55 shows a pronounced magnetic fluctuation around a reciprocal lattice 2D vector Q2D = (0.5, 0). On the other hand, superconductor FeSe0.45Te0.55 shows a magnetic fluctuation at Q2D = (0.5, 0) and (0.5, ±0.5). This result suggests that the AF fluctuations characterized by Q2D = (0.5, ±0.5) may play an important role in superconductivity.
The structure of a dental Ag-Pd-Cu-Au casting alloy has been studied various heat treatments. By SEM, TEM and XRD, the microstructure of as cast material is consisted of α１、α、and βphases. But, microstructure of solution treatment at 1123K change to α、β、and L10 type-ordered β‘phases. And, hardness increases drastically.
BaSi2, composed of abundant chemical elements, has advantages over other solar cell materials. It has a very large absorption coefficient of approximately 3×104cm-1 at 1.5 eV. Furthermore, the band gap can be tune up to 1.4 eV, matching the solar spectrum. We have focused on the epitaxial growth of BaSi2 films on Si(111), and achieved the external quantum efficiency of over 20%, the highest value ever reported for semiconducting silicides.
Single-molecule magnets (SMMs) are a class of metalorganic compounds, which show a slow magnetic relaxation due to magnetic anisotropy of the spin carrier(s). In the recent works, the use of heavy lanthanide ions is becoming popular because of their large spin multiplicity and large magnetic anisotropies in the ground state. We have developed the synthetic strategy to design the magnetic anisotropy, and synthesized an Er(III) SMM by the designing of anisotropy for the first time.