Toshihiko Anno

Preparation of Cu-O Films by Electron Cyclotron Resonance Plasma-Assisted Sputtering

Preparation of Cu-O films has been performed by using electron cyclotron resonance (ECR) plasma-assisted sputtering, and the effects of activated species in the ECR plasma on the properties of Cu-O films have been investigated from measurements of the optical emission spectroscopy. The emission intensities from O2+ molecular ions and O* atomic radicals in the ECR oxygen plasma increase monotonously with increasing microwave power of the ECR plasma source. The oxygen content of Cu-O films can be successfully controlled by changing the microwave power of the ECR plasma source. These results suggest that the role of the activated species of oxygen is important in oxidization of Cu atoms.

Superconducting Properties of YBa 2 Cu 3 O 7-x Films Prepared by ECR Plasma-Assisted Sputtering

Using ECR plasma-assisted ing,¬ YBa<inf>2</inf>Cu<inf>3</inf>O<inf>7-x</inf> films with c-axis orientation were grown epitaxially on (100) SrTiO<inf>3</inf> substrates. YBa<inf>2</inf>Cu<inf>3</inf>O<inf>7-x</inf> films prepared by ECR plasma-assisted sputtering had a smaller lattice constant c and a higher Tc than films prepared by magnetron sputtering alone. Optical emisssion spectroscopy measurements were performed during deposition to investigate the relationship between the superconducting properties of films and the plasma species in the ECR plasma. The film superconducting properties were closely related to the activated particles of oxygen in the ECR plasma.

Superconducting Properties of Li-Doped Bi 2 Sr 2 CaCu 2 O x Thick and Thin Films

The effect of Li additon on the superconducting properties of Bi 2 Sr 2 CaCu 2 O x thick and thin films was investigated. Bi 2 Sr 2 CaCu 2 O x superconducting films were successfully obtained at low temperatures below 840°C by addition of Li2C03, which acted as a flux. The superconducting transition temperature (T c ) of films increases with increasing Li content, accompained by an increase in the c-axis lenghth. The thick and thin films had a T czero of 88K and 81K≫ respectively, higher than the values for undoped Bi 2 Sr 2 CaCu 2 O x .

Preparation of Y-Ba-Cu-O Films by ECR Plasma-Assisted Sputtering

Using ECR plasma assisted-sputtering, epitaxial growth of YBa2Cu3O7−y films with c -axis orientation has been accomplished on a (100) SrTiO3 subsrate. The YBa2Cu3O7−y films prepared by the ECR plasma-assisted sputtering exhibited a shorter latice constant c and a higher Tc than those prepared by only the magnetron sputtering. To investigate the relationship between the superconducting properties of the films and the plasma species in the ECR plasma, measurements of an optical emission spectroscopy in the ECR plasma have been made. The superconducting properties of the films were closely related to the activated particles of oxygen in the ECR plasma.

Crystal Structure of Sr-Ca-Cu-O: A Comparison Between That of Sr-Ca-Cu-O and of Bi-Sr-Ca-Cu-O

A new oxide-superconductor without rare-earth elements, Bi-Sr-Ca-Cu-O, has layered structure with alternative stacking of perovski te-1ike layers, consisting of Sr, Ca, Cu and O, and Bi2O2 layers. We are interested in the contribution of the Bi2O2 layer in this compound to the crystal structure that is closely related to superconductivity. In order to understand the role of the Bi2O2 layer in this type of superconductors, we synthesized Sr-Ca-Cu-O compounds and made a comparison between the structures of Sr-Ca-Cu-O and Bi-Sr-Ca-Cu-O.