| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
This study has been performed to develop new technique to synthesize single crystals of oxide superconductors at low temperature. The study has focused on the synthesis of superconducting cuprates and copper-less oxides by means of electrochemical method. The study consists of three projects ;
1. Synthesis and characterization of transport properties of Ba_<1-x>K_xBiO_3 crystals with various compositions.
2. Synthesis and characterization of single crystal of superconducting cuprates.
3. Search of new copper-less superconducting oxides.
The results of the projects are as follows ;
Project 1 : Transport properties of the material have been revealed by means of precise resistivity and Hall-effect measurements for the crystal with wide range of composition. It is shown, in particular, that the transport property correlates strongly to the changes in the crystallographic phase and that the composition including oxygen affects to the superconductivity. In addition, band scheme of Ba_<1-x>K_xBiO_
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3 has been characterized directly by X-ray absorption measurement in the collaboration with Dept.of Science, Tokyo Univ..
Project 2 : Crystals of the La_2CuO_<4+delta> and Nd_<2-x>Ce_xCuO_4 systems have been successfully grown, and it is shown that the electrochemical method is a unique method for the crystal growth of superconducting cuprates. In particular, La_2CuO_<4+delta> shows superconductivity in as-grown state without any heat treatment in high pressure oxygen, and it is revealed that the crystals grown by the electrochemical method contain enough oxygen to show superconductivity.
Project 2 : Synthesis of oxides containing Nb, Mo, and Ru has been performed. Crystals such as BaRuO_3 have been successfully grown, and characterization of their properties is in progress.
In addition to the projects, we developed new "Electrolysis-cell method" for the synthesis of oxide crystals. In this method electromotive force appeared at the elettrodes is used for the crystal growht. The method was applied to the synthesis of Ba_<1-x>K_xBiO_3 crystal, and it is confirmed that high quality crystals can be grown by the method. Less
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