论文部分内容阅读
自从高临界温度氧化物超导体被发现以来,元素替代一直是人们探索其超导电性产生机制和寻找新的超导体系的有效方法之一.在YBaCuO体系中,对于Y位替代的大量实验结果表明,稀土元素中除Pr,Ce,Tb外都能形成正交的123相,并保持临界温度在90K左右的超导电性.目前,关于Y_(1-x)Pr_xBa_2Cu_3O_y体系虽然保持正交123相但并不是高温超导体的研究已有大量的报道,然而对于掺Ce的(Y,Ce)Ba_2Cu_3O_y系统的研究则报道较少,对于掺Ce的YBaCuO体系超导临界温度下降甚至不超导的原因目前主要有两种观点:其一认为用固相反应法在常规合成条件下,完全或部分替代Y都不可能得到单一的123相,但是有限的Ce能够进入123相并导致123相正交向四方的转变,从而影响超导电性;另一种观点则认为Ce
Element substitution has been one of the most effective ways to explore the mechanism of superconductivity and to find new superconducting systems since high-temperature oxide superconductors were discovered.In the YBaCuO system, a large number of experimental results on the substitution of Y-sites show that , The rare earth elements except Pr, Ce, Tb can form orthogonal 123 phase, and maintain the critical temperature of about 90K superconductivity.At present, about Y_ (1-x) Pr_xBa_2Cu_3O_y system to maintain orthogonal 123 phase However, there are few reports on the (Y, Ce) Ba_2Cu_3O_y system doped with Ce, and the reason why the critical temperature of superconductivity of YBaCuO doped with Ce decreases or is not superconducting is currently the main reason There are two kinds of viewpoints: one considers that it is impossible to obtain a single 123 phase by completely or partially substituting Y under the conventional synthesis conditions by the solid-phase reaction method, but limited Ce can enter the 123 phase and cause the 123 phase to be orthogonal to the tetragonal Change, thus affecting the superconductivity; another view is that Ce