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Herein the authors propose a compositional thermoelectric phase diagram, which includes the density of states effective mass (md*) carrier relaxation time (τ), and thermoelectric power factor (S2σ, where S and σ are Seebeck coefficient and electrical conductivity) for high-quality epitaxial films composed of 20%-Nb-doped CaTiO3–SrTiO3–BaTiO3 solid solutions [(Ca,Sr,Ba)(Ti0.8Nb0.2)O3]. The md* values almost proportionally increase with the in-plane lattice parameter of (Ca,Sr,Ba)(Ti0.8Nb0.2)O3 epitaxial film, while the τ values drastically decrease when Ca and/or Ba are substituted for Sr in Sr(Ti0.8Nb0.2)O3, indicating that the Sr-site substitution negatively affects the thermoelectric performance of Nb-doped SrTiO3.

Investigation on variation of the electronic structure accompanying the electrochemical lithium insertion into the perovskite type oxide, (Li,La)TiO3, has been carried out by X-ray absorption spectroscopy (XAS). During the electrochemical lithium insertion, titanium ion reduced its oxidation state from Ti4+ to Ti3+, while La3+ does not contribute to the reduction reaction resulting from Ti K-edge and La L3-edge XAS, respectively. Furthermore, O K-edge XAS showed marked spectral changes with electrochemical lithium insertion, indicating the electronic structure around oxide ion affected by lithium insertion reaction. From the XAS measurement, we have concluded the variation observed in O K-edge XAS was related to the strong interaction with inserted Li ion. To confirm this, first-principles band calculations were performed for the perovskite structure before and after electrochemical lithium insertion. The calculated results showed that the electron originated from inserted Li transferred to neighboring oxide ion locally as well as to Ti ion. This may be due to local neutralization effect of Li to reduce the electrostatic interaction in the crystal.

Although composite resin core is used with various types of prefabricated posts, it remains unclear which kind of material is most suitable for the post. The aim of this study was to evaluate the influence of prefabricated posts on the stress distribution within the root by finite element analysis. Posts and cores were built up with composite resin and four types of prefabricated posts: two types of glass fiber posts (GFP1, GFP2) with low and high Young's moduli, a titanium post (TIP), and a stainless steel post (SSP). In all models, stress distribution during function was calculated. There were differences in stress concentration at the root around the end of posts. The magnitudes of stress for GFP1, GFP2, TIP, and STP were 8.7, 9.3, 11.7, and 13.9 MPa respectively. Given the results obtained, GFP1 was the most suitable material for post fabrication since this model showed a lower stress value. It would therefore mean a lower possibility of root fracture.

Using a newly developed transmission-type photocathode, an electron beam of super-high brightness [ð1:3 AE 0:5Þ Â 10 7 AÁcm À2 Ásr À1 ] was achieved. Moreover, the spin-polarization was as high as 90%. We fabricated a transmission-type photocathode based on a GaAs-GaAsP strained superlattice on a GaP substrate in order to enhance the brightness and polarization greatly. In this system, a laser beam is introduced through the transparent GaP substrate. The beam is focused on the superlattice active layer with a short focal length lens. Excited electrons are generated in a small area and extracted from the surface. The shrinkage of the electron generation area improved the brightness. In addition, a GaAs layer was inserted between the GaP substrate and the GaAsP buffer layer to control the strain relaxation process in the GaAsP buffer layer. This design for strain control was key in achieving high polarization (90%) in the transmission-type photocathode. #

GaAs-GaAsP and InGaAs-AlGaAs strained-layer superlattice photocathodes are presented as emission sources for highly polarized electron beams. The GaAs-GaAsP cathode achieved a maximum polarization of 92(±6)% with a quantum efficiency of 0.5%, while the InGaAs-AlGaAs cathode provides a higher quantum efficiency (0.7%) but a lower polarization (77(±5)%). Criteria for achieving high polarization using superlattice (SL) photocathodes are discussed based on experimental spin-resolved quantum efficiency spectra.

We demonstrate room temperature pulsed operation of nitride based multi-quantum-well (MQW) laser diodes with cleaved mirror facets grown on a conventional C-face sapphire substrate. Cleavage was performed along the <11*BAR*2*BAR*0> direction of the sapphire substrate, and the resultant facet was analyzed using an atomic force microscope (AFM) and theoretical calculation. A single peak emisson, at a wavelength of 417.5 nm, with a full width at half-maximum of 0.15 nm, was obtained. The threshold current density of the laser was 50 kA/cm2 and a voltage for the threshold current was 20 V.