Takeshi Kishimoto

X-ray photoelectron spectroscopy study in Bi2Sr2Ca1-xNdxCu2O8+d

X-ray photoelectron spectroscopy (XPS) measurements were performed in Bi2Sr2Ca1-xNdxCu2O8+d (0≤x≤1) in order to investigate the change in the electronic states through the decrease of the holes in this system. The negative chemical shifts of the Cu 2p main peaks were observed, while their satellites did not shift but decreased in areas. These behaviors indicated that the holes at both Cu and O sites decrease with increasing Nd concentration x.

EFFECT OF NI SUBSTITUTION FOR CU IN 110 K PHASE OF (BI, PB)-SR-CA-CU-O SUPERCONDUCTORS

The effect of Ni substitution for Cu in the 110 K phase of (Bi, Pb)-Sr-Ca-Cu-O superconductor was investigated. Samples of Bi1.84Pb0.34Sr1.91Ca2.03(Cu1-xNix)3.06Oy were prepared. The single phase was obtained up to a Ni concentration of x=0.015. The zero-resistance temperature Tc decreased monotonically in the region of x≤0.03 and became 90 K at x=0.03. Tc remained constant at 89 K in the region of 0.03<x≤0.10. Through X-ray photoelectron spectroscopy measurements, the Cu 2p core level was found to shift toward lower binding energy with the increase of x, which shows the Ni substitution for Cu.

Effect of Y substitution for the Ca site in the 110 K phase of (Bi, Pb)-Sr-Ca-Cu-O superconductors

The effect of the substitution of the trivalent Y ions for the divalent Ca ions has been studied in the 110 K phase of Bi1.84Pb0.34Sr1.91(Ca1-xYx)2.03Cu3.06O10+y (x=0~0.05). We found the solubility limit of Y to the 110 K phase around x=0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature Tc gradually decreased with the increase of x, corresponding to the decrease of the carrier concentration.

Effect of Y Substitution for Ca in Bi2Sr2CaCu2O8+d Superconducting Films Prepared by Liquid Phase Epitaxial Method

The effect of Y substitution for Ca on superconducting properties has been investigated in Bi2Sr2CaCu2O8+d films prepared by liquid phase epitaxial method. The Y concentration in the film, xS, increased in proportion to that in the solution, xL, in the region of 0≤xL≤0.2, and then it was saturated. The incorporation ratio of Y in solid and in liquid, xS/xL, for 0≤xL≤0.2 was found to be about 3. The xS dependences of the zero-resistance temperature and the carrier concentration showed that about half of the Y concentration incorporated in the films contributes to the effect of the Y substitution obtained in sintered materials.

Computer Simulations of Quench Properties of Thin, Large Superconducting Solenoid Magnets

Measured quench data of a 1 m ×1 m thin superconducting solenoid magnet with a single layer aluminum-stabilized NbTi/Cu superconductor of 269 turns were fitted by computer simulations using the one-dimensional approximation. Parameters obtained were used to study quench properties of a 3 m ×5 m (1.5 Tesla) thin superconducting solenoid magnet with a stored magnetic energy of 30×106 J. Conductor dimensions with which the solenoid could be built substantially safe for the full field quench were optimized.

Development of Highly Stable Synchrotron Radiation Source at SORTEC

The construction and the initial beam conditioning of a 1-GeV synchrotron radiation (SR) source facility at SORTEC Corporation were successfully completed in 1989. The regular operation for lithography experiments was started in April 1990, and highly stable operation has been maintained for over one year. At present, the beam lifetime with the stored beam of 200 mA has reached over 50 hours. Due to stable beam refilling into the storage ring, automatic operation for a constant level control of the stored beam current was also successfully confirmed. In this paper, performance of the SR source will be further discussed from the viewpoint of the industrial use of the SR source for X-ray lithography in terms of stable and flexible operation, operation efficiency, utilities and radiation safety.

X-ray photoemission spectroscopy study on Bi2Sr2-x Ca1+x Cu2O8+d

Abstract We have elucidated the distribution of the Sr and Ca atoms in the Bi2Sr2-x Ca1+x Cu2O8+d system (0  ′  0.8) by X-ray photoemission spectroscopy (XPS). The carrier concentration and the superconducting temperature Tc have a maximum at x = 0.2 and then monotonously decrease with increasing x. From the XPS measurements, the Sr3d and Ca2p spectra are found to be decomposed into two states. We have clarified the occupation of the Sr and Ca atoms in the Sr-and Ca-layers and found that the deficiency in the Sr-layer has a great influence on superconductivity.

Y doping effect on superconducting properties in Bi2Sr2CaCu2O y films prepared by liquid phase epitaxial method

Abstract The Y doping effect on superconducting properties has been studied in Bi2Sr2CaCu2O y films prepared by the liquid phase epitaxial method. The incorporation ratio of each element in the LPE film to that in the melt was investigated as a function of Y content in the solution. The change of the superconducting properties due to the Y doping was connected with the total amount and the composition ratio of Sr, Ca and Y in the film.