Crystalline Engineering using High Magnetic Field for Fabrication of Functional Materials

点击翻译按钮获取中文摘要

The purpose of this project is investigation on effects of magnetic field to the melt-growth process and clarification of magnetic properties of several novel materials. For this purpose we have chosen high temperature superconductors such as RE123 system and Bi system, thermoelectric materials such as bismuth cobaltite and Ca12Al14O33 for optoelectronic applications. Effects of magnetic fields during melt growth for ErBa2Cu3Oy, Ca12Al14O33 and (Bi.Pb)2Sr2Co2Oy were clarified. While there were not clear effect on crystallinity but several positive effects were observed on the behavior of oxygen bubbles and distribution coefficient of cations at liquid-solid interface in a floating zone method. In the case of peritectic reaction, improvement of crystallinity was observed and the control of orientation in layered oxide by magnetic field has been also intensively studied. We have investigated changes of magnetic anisotropy and easy axis of magnetization induced by locally structural changes and magnetic ions in various layered systems. In the case of RE123 system, it was found that RE ions had crucial role not only to easy axis of magnetization but also determination factor of magnetic field for orientation. In best case minimum magnetic field for control of was estimated around 1T, and this value was one order of magnitude smaller than that of usual superconducting magnet.