Study on Phase Diagram of Ba-Cu-Y-O Quaternary System and Microstructure Control of Superconductor

Ba-Cu-Y-O四元系相图及超导体微观结构控制研究

基本信息

批准号：
63460202
负责人：
OSAMURA Kozo
金额：
$ 4.61万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Phase diagram of Y-Ba-Cu-O four component and ite relating three component systems have been investigated under air of mixed gas of oxygen with argon. In order to determine experimentally the phase diagrams, powder X-ray diffraction, EMPA, microscop13EA\ : ic observation and thermal analysis were carried out. When the carbonates are used as starting materials and/or the specimen is calcined in natural air including carbonic acid gas, some ternary and quaternary oxycarbonates are easily formed. In the Y-Cu-O ternary system, there are five phases of Y_2O_3, CuO, Cu_2O, YCuO_2 and Y_2Cu_2O_5 and these phases compose the phase diagram depending on oxygen partial pressure. In the Ba-Cu-O ternary system, there are three ternary phases of BaCuO13EA\ : _2 and two polymorphisms of Ba_2CuO_3 under oxygen pressure around 1 atm. In the Ba-Y-O ternary system, it was found that two phases of Y_4Ba_4O_9 and Y_2BaO are the true oxide, but other phases reported till now are oxycarbonates. In the qua13EA\ : ternary system, five quaternary phases YBa_2Cu_3O_<6+x>, Y_2BaCuO_5, YBa_4Cu_3O_<8.5>, YBa_6Cu_3O_<10.5> and YBa_2Cu_4O_<7.5> are stable under air. Three isothermal sections at 1263, 1223 and 1173 K were determined and the phase relation has b13EA\ : een in detail investigated. Combining the results of htermal analysis, the whole sequence diagram for univariant reactions has been established in the Y-Ba-Cu-O quaternary system under oxygen partial pressure of 0.21 atm. Furthermore, two invariant reactions were confirmed to exist in the quaternary system from the oxygen partial pressure dependence of phase relations. Based on the knowledge mentioned above, the control of microstructure has been discussed to improve superconductivity.

Y-BA-CU-O的相图四个组件和ITE与三个组件系统有关，在与氩气的混合气体的空气下进行了研究。为了实验确定相图，进行了粉末X射线衍射，EMPA，显微镜13EA \：IC观察和热分析。当将碳酸盐用作起始材料和/或样品在包括碳酸气体在内的天然空气中钙化时，很容易形成一些三元和四氧碳酸盐。在Y-Cu-O三元系统中，Y_2O_3，CuO，Cu_2O，YCUO_2和Y_2CU_2O_5的五个阶段，这些阶段取决于氧气部分压。在BA-Cu-O三元系统中，Bacuo13ea \：_2的三个三元阶段和BA_2CUO_3的两个多态性在1个atm左右的氧气压力下。在BA-Y-O三元系统中，发现Y_4BA_4O_9和Y_2BAO的两个阶段是真正的氧化物，但到目前为止报道的其他阶段是氧气。在qua13ea \：三元系统中，五个第四纪阶段yba_2cu_3o_ <6+x>，y_2bacuo_5，yba_4cu_3o_ <8.5>，yba_6cu_3o_ <10.5>和yba_2cu_2cu_4o__4o__4o__4o_ <7.7>在稳定的空气下。确定了1263、1223和1173 K时的三个等温部分，并详细研究了相位关系B13EA \：EEN。结合了Hmermal分析的结果，在氧局部压在0.21 atm下，在Y-BA-CU-O-O四级系统中建立了单变量反应的整个序列图。此外，从相关的氧部分压力依赖性中证实，在第四纪系统中证实了两个不变反应。根据上述知识，已经讨论了微观结构的控制以提高超导性。