Kenichi Bushida

Sensitive Stress-impedance Micro Sensor Using Amorphous Magnetostrictive Wire

A giant stress-impedance (GSI) effect with the strain-gauge factor more than 1200 was found in negative magnetostrictive amorphous CoSiB wires of 30-/spl mu/m diameter magnetized with a high frequency current or a sharp pulse current. A sensitive stress sensor is constructed using a CMOS IC multivibrator circuit in which the amorphous wire is magnetized with a sharp pulse train current. The amorphous wire GSI sensor will be applied for detection of such as pressure, tension, stream speed for liquid and gases and mechano-cardiogram with the sensitivity of 5-6 times higher than that of the semiconductor stress sensors utilizing the piezo-resistance effect showing a gauge factor of about 200.

Electronic Structures and Superconducting Mechanism of Ba2Y1Cu3O7

The high-Tc superconductor Ba2Y1Cu3O7 with the oxygen-deficient perovskite structure was prepared almost in a single-phase with Tco of 125 K, Tc of 95 and Tce of 93 K. The XPS valence-band spectrum showed a relative large N(EF), density of states at the Fermi level. The XPS Cu 2p3/2 peak is divided into three peaks which are attributed to monovalent, bivalent and trivalent Cu ions with the concentration ratio of 1:2:1. These results and the peculiar lattice structure lead to the Tc enhancement mechanism from the plasmon or exciton origin due to the Cu d-hole creation and annihilation resonating with vibration modes of the CuO5 and CuO4 clusters. The Tc value was calculated.

Magneto-Impedance Element Using Amorphous Micro Wire

A large magneto-impedance (MI) effect was found in amorphous magnetic wires while passing a high-frequency current. The amplitude of the induced voltage between the ends of a wire changes by 40 to 50% when an external magnetic field of about 10 Oe (approximately 800 A/m) is applied parallel to the wire axis. This paper reports the principles and basic properties of the MI effect in very small amorphous wires of composition (Fe0.06Co0.94)72.5Si12.5B15 and magnetostriction ¿10¿7, and describes an application to rotary encoder heads using very small MI elements 30 ¿m in diameter and 1 mm in length.

Recent Advances of Amorphous Wire CMOS IC Magneto-Impedance Sensors: Innovative High-Performance Micromagnetic Sensor Chip

We analyzed and organized the reasons why the amorphous wire CMOS IC magneto-impedance sensor (MI sensor) has rapidly been mass-produced as the electronic compass chips for the smart phones, mobile phones, and the wrist watches. Comprehensive advantageous features regarding six terms of (1) microsizing and ultralow power consumption, (2) high linearity without any hysteresis for the magnetic field detection, (3) high sensitivity for magnetic field detection with a Pico-Tesla resolution, (4) quick response for detection of magnetic field, (5) high temperature stability, and (6) high reversibility against large disturbance magnetic field shock are based on the magneto-impedance effect in the amorphous wires. We have detected the biomagnetic field using the Pico-Tesla resolution MI sensor at the room temperature such as the magneto-cardiogram (MCG), the magneto-encephalogram (MEG), and the self-oscillatory magnetic field of guinea-pig stomach smooth muscles (in vitro) that suggest the origin of the biomagnetic field is probably pulsive flow of Ca2

Structure refinement of the Cu6O8. YCl compound

Abstract The Cu6O8 · YCl compound belongs to the family of Cu6O8 · MX compounds, where M is a positive ion (i. e. Cu, In, Rare earth) and X is a negative (i.e. Cl, NO3). This new compound was synthesized and its structure was refined by X-ray powder diffraction using the Rietveld method. It was proved that the chemical formula of these compounds is Cu6O8 · MzX, where Z ≦ 6. The space group is Fm 3 m with unit cell parameters a = 9.2871 A . The final stoichimetric value of z is correlated with the ionic radius of the M-atom; in the case of Y, z = 1.

Synthesis and properties of new cubic Cu6O8·MX compounds as a candidate of cubic copper oxide superconductors

Abstract The new cubic Cu 6 O 8 ·MX compounds (M=In,Sc,Cu,Y and Pb, and X=NO 3 and Cl) may be candidates for High-Tc superconductors. They have high structure symmetry (Fm3m) and CuO 4 -clusters as structural units which play an important role to the mechanisms of superconductivity. The preparation method, the structure refinement, the electronic and magnetic properties were studied from X-ray diffraction, XPS, resistivity and magnetic susceptibility data.

Phase Modulation Device Using Amorphous Short Wire

A new phase-modulation device with simple structure and high reliability was constructed using a short amorphous wire. A high-frequency ac current (carrier) and a signal current are simultaneously passed through the wire, which undergoes the large Barkhausen effect when the circumferential flux changes. Highly linear modulation characteristics were obtained up to 0.67¿ using a triangular-wave ac current, passed through tension-annealed wire 30 ¿m in diameter and 5 mm in length. This simple yet reliable phase modulation device is expected to find applications in the field of factory automation communication networks.

Possibility of cubic copper-oxide superconductors with high Tc

Abstract Empirical rules on high Tc superconductors with cubic lattice structure are derived. High entropy state of lattice, high degeneracy of energy levels and high possibility of electronic and lattice instability are key factors for cubic superconductors with high Tc. The electronic instability from the parallel Fermi-surfaces and parallel bands can be a common important factor with the layered copper-oxide superconductors. On the basis of the rules, some cubic-structured copper-oxides with inversion symmetry were proposed as high Tc superconductors.

DETERMINATION OF THE AVERAGE VALENCY OF COPPER IN THE NEW CONDUCTING MATERIALS Cu-O-M-X(M=In, Cu, X=CL, NO 3 ) AND SUPERCONDUCTOR Y-Ba-Cu-O SYSTEMS BY REDOX TITRATION METHOD

Oxidation states of copper in Cu-O-M-X (M=In, Cu, X=C1, NO 3 ) and Y-Ba-Cu-O systems have been determined by redox titration. After highlt oxidized copper was directly reacted with excess ferrus ions in acidic solution, residual ferrous ions have been titrated with standardized bichromate solutions

Upper critical field of SrxLa2−xCuO4−y

The electrical resistance of SrxLa2-xCuO4-y has been measured under magnetic fields up to 21.1 T between 4.2 and 50 K. The onset of Tc was 41.0 K in H=0 and 33.0 K in H=21.1 T. H2c(0) is estimated to be 76 T according to the dirty limit theory of type II superconductivity. The Hc2 value is near the Pauli limit value and is higher than that (60 T) of PbMo6S8. SrxLa2-xCuO4-y is one of the highest-Hc2 superconductor as well as a high-Tc one.