In-plane Anisotropy on Resistivity and Thermopower in The Misfit Layered Oxide Bi2-xPbxSr2Co2Oy

We investigated the in-plane anisotropy on the resistivity and thermopower of Bi2-xPbxSr2Co2Oy single crystals, which have a misfit structure between the hexagonal CoO2 layer and the rock salt Bi2Sr2O4 layer. The resistivity and thermopower show significantly large anisotropy, which exceeds two at maximum. This anisotropy would come from the anisotropic pseudogap formation enhanced by the misfit structure. The thermopower changes with Pb doping to take a maximum at x=0.4. The misfit structure improves the thermoelectric properties through chemical pressure. The power factor is as large as 9 muW/cmK2 at 100 K for x=0.6, which is the highest value for thermoelectric oxides at 100 K.Comment: 4 pages, 3 figures, submitted to Jpn. J. Appl. Phy

Method for evaluating material viscoelasticity

A method for evaluating the viscoelasticity of materials under oscillation load is proposed. In the method, a material under test is connected to a mass, which generates an oscillating inertial force after the mass is manually struck using a hammer. A pneumatic linear bearing is used to realize linear motion with sufficiently small friction acting on the mass that is the moving part of the bearing. The inertial force acting on the mass is determined highly accurately by means of measuring the velocity of the mass using an optical interferometer

Diacetyl as Acetyl Donor

Diacetyl can serve as an acetyl donor for the forlnation of citrate and the acetylation of sulfanilamide in the dog heart homogenate. Diphosphothiamine and coenzyme A are essential for these reactions.</p

Pseudogap Phase Boundary in Overdoped Bi_2Sr_2CaCu_2O_8 Studied by Measuring Out-of-plane Resistivity under the Magnetic Fields

The characteristic pseudogap temperature T* in Bi2Sr2CaCu2O8 system has been systematically evaluated as a function of doping, especially focusing on its overdoped region, by measuring the out-of-plane resistivity under the magnetic fields. Overdoped samples have been prepared by annealing TSFZ-grown Bi2Sr2CaCu2O8 single crystals under the high oxygen pressures (990 kgf/cm2). At a zero field, the out-of-plane resistivity showed a metallic behavior down to Tc (= 62 K), while under the magnetic fields of over 3 T,it showed typical upturn behavior from around 65 K upon decreasing temperature. This result suggests that the pseudogap and superconductivity are different phenomena.Comment: 2 pages, 2 figures. Final version accepted for the Proceedings of the M2S-IX Conference (Tokyo, September 2009