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Search for High T_c Superconductors Capable Selective Doping

寻找具有选择性掺杂能力的高温超导体

基本信息

批准号：
03555001
负责人：
UCHIDA Shin-ichi
金额：
$ 3.97万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03555001/
关键词：
Oxide Superconductors Copper Oxides Bismuth Oxides P-Type Doping N-Type Doping Superconducting PN Junction PrBa_2Cu_3O_7 PrBa_2Cu_3O_7 高温超伝導酸化物 P型ド-ピング N型ド-ピング Y系超伝導体 Pr置換体

项目摘要

The purpose of the project is to search for high T_c marerials suitable for the electronic device application. Two approaches have been adopted. One is a search for materials with less anisotropy and longer coherence length which would relrese the difficulty in utilizing the high-T_c materials for conventional superconducting devices such as Josephson and three-terminal devices. It has been demonstrated that a perovskite oxide, Ba_<1-x>K_xBiO_3 with T_c=30K, is most promising and there is a possibility to fabricate all-oxide-SIS junctions using this material.The second is to search for potential materials which might lead to the development of a novel high T_c electronic device using properties unique to high T_c's. PrBa_2Cu_3O_7 - Pr-substituted compound of YBa_2Cu_3O_7(Y123) - is found to be a most interesting candidate. The present study has revealed that the CuO_2 planes in Pr123 are not doped with holes, which is the reason for non-metallic property, due to relatively small Madelung energy difference between in-plane O and Cu site as well as to the valence fluctuation of Pr. The magnitude of the Madelung energy difference is comparable with that in Pr_2CuO_4, a parent material of N-type high T_c superconductors. This fact strongly suggests that Pr123 might be doped with electrons. Attempts for N-type doping have been made by substituting Ce for Pr, La for Ba or F for O, though N-type doping has not been successful yet. If Pr123 were made an N-type superconductor, it would open a door to the development of a novel high T_c device with superconducting PN junctions in a Pr123/Y123 superlattice. Pr123/Y123 superlattice.

本课题的目的是寻找适合于电子器件应用的高T_c材料。采取了两种办法。一是寻找各向异性小、相干长度长的超导材料，以解决高T_c超导材料在常规超导器件如约瑟夫森和三端器件中应用的困难。研究表明，<1-x>T_c= 30 K的钙钛矿型氧化物Ba_ K_xBiO_3是最有前途的材料，有可能用它来制备全氧化物-SIS结。PrBa_2Cu_3O_7 -Pr取代YBa_2Cu_3O_7（Y_（123））-的化合物是一个很有意义的候选者。研究表明，Pr_（123）中CuO_2面没有空穴掺杂，这是由于面内O位和Cu位的Madelung能差较小以及Pr的价态涨落所致，其Madelung能差的大小与N型高温超导体母体Pr_2CuO_4相当。这一事实有力地表明Pr 123可能掺杂了电子。虽然N型掺杂还没有成功，但已经尝试通过用Ce代替Pr、La代替Ba或F代替O来进行N型掺杂。如果Pr 123成为N型超导体，将为在Pr 123/Y 123超晶格中研制新型高T_c超导PN结器件打开一扇大门。Pr 123/Y123超晶格。