Fluorohalogenation of superconducting oxide YBa2Cu3O7−δ with ClF3
Fluorohalogenation of superconducting oxide YBa2Cu3O7−δ with ClF3
复制标题
超导氧化物 YBa2Cu3O7−δ 与 ClF3 的氟卤化
DOI：
10.1016/s0022-1139(99)00055-x
复制
发表时间：
1999
影响因子：
1.9
通讯作者：
M. Matsumiya
中科院分区：
文献类型：
--
作者：
M. Takashima;S. Yonezawa;Mitsunobu Aoyama;M. Matsumiya
将低T_c相YBa2Cu3Ox(x∼6.6，Tc∼60K)烧结成致密片，在气相ClF_3中进行氟化反应，以研究烧结YBa2Cu3Ox的氟卤化机理。结果表明，在无氧的情况下，样品的外层形成了氟化的高T_c相YBa2Cu3OxFyClz(x∼6.6，y∼0.5，z∼0.1)，内部也形成了高氧低卤量的高T_c相(x∼6.8，y∼0.1，z∼0.0 1)。Rietveld分析表明，氟氯化高T_c相YBa2Cu3OxFyClz(YBa2Cu3O6.10F0.75Cl0.49，T=94.5K)的中子粉末衍射数据表明，氟优先占据氧缺陷位和/或铜氧链上的空位。另一方面，由于氯−太大而不能占据氧缺陷位和/或铜氧链上的空位，所以氯以氯的形式占据了被氧包围的Y中心的(0，0，1/2)位。经ClF3处理的样品被认为至少由两个相组成：正交相YBa2Cu3O6.35F0.65Cl0.49(Pmmm)和四方相YBa2Cu3O6.29F1.17Cl0.49(P4/mmm)。Rietveld修正得到的化学式为YBa2Cu3O6.33F0.80Cl0.49，与所分析的化学成分YBa2Cu3O6.35F0.75Cl0.49非常接近，其中氯被认为是零价的。
The low-Tc phase YBa2Cu3Ox(x∼6.6, Tc∼60K) which was sintered into a dense tablet was subjected to gaseous ClF3, in order to investigate the mechanism of fluorohalogenation of a sintered YBa2Cu3Ox. It was found that the fluorochlorinated high-Tc phase YBa2Cu3OxFyClz(x∼6.6, y∼0.5, z∼0.1) was formed at the outer part of sample tablet, and that the high-Tc phase with high oxygen and low halogen contents (x∼6.8, y∼0.1, z∼0.01) was also formed at the inner part of it, despite of no oxygen in the reaction atmosphere. Rietveld analysis of neutron powder diffraction data of the fluorochlorinated high-Tc phase YBa2Cu3OxFyClz(YBa2Cu3O6.10F0.75Cl0.49, Tonset=94.5K) revealed that fluorine preferentially occupied the oxygen defect site and/or the vacant site along the Cu–O chain. On the other hand, chlorine occupied as Cl the site at (0, 0, 1/2) which was the center of the yttrium site surrounded with oxygen because Cl−was too large to occupy the oxygen defect site and/or the vacant site along the Cu–O chain. The ClF3-treated sample was considered to consist of at least two phases of the orthorhombic YBa2Cu3O6.35F0.65Cl0.49(Pmmm) and the tetragonal YBa2Cu3O6.29F1.17Cl0.49(P4/mmm). The chemical formula estimated by the Rietveld refinement was YBa2Cu3O6.33F0.80Cl0.49which was very close to the analyzed composition, YBa2Cu3O6.35F0.75Cl0.49in which chlorine was assumed to be zero-valence.