Hidetaka Shintaku

Fabrication of Ag-Doped Y1Ba2Cu3O7-x Superconducting Films on Cu Substrates by Electrophoretic Deposition

Ag-doped Y1Ba2Cu3O7-x superconducting films were fabricated on Cu substrates by electrophoretic deposition. The electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x and Ag2O powder dispersed in distilled acetone. The deposited films were heat-treated in air at 900°C. The Ag-doped Y1Ba2Cu3O7-x films on Cu-coated YSZ exhibited a metallic temperature dependence of the resistance, and the zero-resistance state was obtained at 88 K. The critical current density and the grain growth were greatly improved by the Ag doping.

Fabrication of Y-Ba-Cu-O superconducting films on Cu substrates by an electrophoretic deposition technique

Direct formation of Y1Ba2Cu3O7-x films on Cu substrates by electrophoretic deposition is studied, Electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x powder dispersed in distilled acetone. The deposited films were annealed in air at 900°C. We succeeded in obtaining superconducting Y1Ba2Cu3O7-x films on Cu substrates. The films on Cu plates and Cu film/YSZ exhibited the zero-resistance state at 66 K and 76 K, respectively. Interfacial chemical reactions at the Y1Ba2Cu3O7-x/Cu interface are discussed. The achievement of the zero-resistance state is considered to be due to the reduction of the interfacial reactions.

Magnetic field dependence of voltage noise in Y1Ba2Cu3O7-x ceramic superconductor film

Magnetic field dependence of voltage noise in a ceramic superconductor Y1Ba2Cu3O7-x film has been investigated. We have observed a maximum of the noise at about 10 Oe for the perpendicular field to the film surface. For the parallel field to the film surface, the noise increases slightly with the increase of the field. These noise characteristics are considered due to a motion of magnetic flux in the film.

Study of Ag Addition to YBa2Cu3O7-x Films Prepared using Electrophoretic Deposition

Ag addition to YBa2Cu3O7-x superconducting films prepared using electrophoretic deposition on Cu substrates was investigated. The electrical characteristics of the films, such as zero-resistance temperature (Tc), critical current density (Jc), and resistivity at room temperature (ρ) were greatly improved by Ag doping. The Tc of 94 K was attained with the electrophoretic Ag-doped film on Cu substrate. By doping with Ag, the grain growth was enhanced but no shift in YBa2Cu3O7-x peaks was observed in X-ray diffraction patterns. From the electron probe microanalysis of the sample cross section, the doped Ag was found to exist in the region devoid of YBa2Cu3O7-x grains.

Fundamental characteristics of a magnetoresistive sensor using Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ ceramic superconducting films

The fundamental characteristics of a magnetic sensor fabricated from a Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ ceramic superconducting film are investigated. The operation principle of the sensor is based on the magnetoresistive properties of the material. The Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ ceramic film was prepared by the spray pyrolysis method. An element of the magnetic sensor consists of the film patterned to a meander shape. the sensitivity is discussed in connection with the noise measurement of the element. A magnetic field resolution of 2*10/sup -6/ G/(Hz)/sup 1/2/ at 100 Hz was obtained in the 0.1-100 G range. The sensitivity is much higher than that of a conventional semiconductor magnetic sensor. With an AC modulation provided by a magnetic field, phase detection of the magnetic field can be performed using a lock-in amplifier. An improvement in the low-frequency ( >

Improvement in sensitivity of novel magnetic sensor using Y-Ba-Cu-O ceramic superconductor film

The authors report an improvement in the sensitivity of a magnetic sensor made of high-T/sub c/ ceramic superconductor. The sensitivity is discussed in connection with the noise measurement of a film element. It is believed that a high sensitivity comparable to that of a high-T/sub c/ SQUID (superconducting quantum interference device) utilizing ceramic materials can be obtained with the present magnetoresistive superconductive element. The magnetic field dependence of the electric resistance of the element at 77 K is shown. The sensitivity as a function of the current is compared for various elements. It is found that the sensitivity of this element is about 100000 times higher than that of a bulk element reported last year. The magnetoresistance at low magnetic field is attributed to the weak couplings between superconductive grains in a ceramic semiconductor. Thus the ceramic superconductor is considered to be a multiconnected Josephson network. The noise is mainly due to the presence of trapped magnetic flux. The reduction of the noise for parallel magnetic field implies the elimination of the trapped flux. Noise measurements are also reported.<<ETX>>