Soichi Ogawa

High-Energy Ion Beam Analysis of YBa2Cu3Ox Thin Films

The composition and crystalline structure of high-Tc superconducting YBa2Cu3Ox thin films formed on MgO(100) and Si(100) substrates have been investigated by Rutherford backscattering and channeling techniques. Y, Ba, Cu contents have been analyzed by employing a high-energy (over 4.5 MeV) 4He ions and large scattering angle (near 170°) condition, where Y, Ba and Cu peaks are clearly separated from each other. Oxygen concentration has been obtained through the use of low primary energy (below 2.5 MeV) and small scattering angle (below 150°) conditions, where the O peak is separated from the background. The crystalline quality of the films has also been investigated by ion channeling techniques.

The effect of charged particles when preparing ZnO thin film by ion beam sputtering deposition

Abstract Zinc oxide films have been prepared by ion beam sputtering deposition. The irradiation effects of the charged particles on the ZnO film crystallographic orientation during deposition are studied. Two methods are adopted to control the bombardment of the charged particles. One applies a bias voltage to the substrate, and the other bombards the substrate with ions. When the substrate is positively biased, the c -axis preferred orientation of the ZnO film is destroyed by the negatively charged particles. When the substrate is negatively biased, or irradiated with argon ions from a side ion gun, certain conditions lead to c -axis orientation. When the substrate is irradiated with oxygen ions, a change to c -axis orientation can clearly be observed. Positive oxygen ion irradiation presumably has an effect on the formation of ZnO film c -axis orientation.

High Magnetic Field Shielding Devices with Superconducting NbTi-Cu Multilayer Films

We have studied the magnetic shielding effects of various hollow disks with superconducting NbTi-Cu multilayer films in vertical magnetic field. The hollow disk has an outer diameter(O.D.) of 60mm and an inner diameter(I.D.) ranging from 0 to 40mm by using the multilayer films composed of two NbTi-Cu layers which NbTi or Cu layer is 5.0um thick, respectively. As the increasing I.D. of the disks from 0 to 40mm, ΔBm (maximum magnetic shielding effects) decreased from 0.11 to 0.024-T. These studies have developed for high magnetic shielding devices which were formed by piling the hollow superconducting disks and A1 disks alternately. The device provided a space free from high magnetic field up to 0.8T.

MAGNETIC SHIELD EFFECTS OF SUPERCONDUCTING NbTi-Cu MULTI-LAYER FILMS

We have carried out the experimental study on magnetic shield effects of NbTi-Cu multilayers film deposited alternately NbTi and Cu films of various thickness. The thickness dependence of ΔBm/nd (ΔBm:max. magnetic shield effect, [d]:film thickness) with the parameter of the number of NbTi layers (n) for the multilayers film are investigated. In the region of [nd]>3μm and in any case of [n]=1,2,3,ΔBm/nd increases exponentially with decreasing [nd] and increasing [n].The relation between ΔBm/nd and [nd] is given the following formula in(ΔBm/nd)=α-βin(nd), α,β (constant). From these results, it is possible to completely seal off a magnetic field of a tesla or more by laminating NbTi-Cu multilayers film of reasonable thickness.