Chemical Bond Properties and Isomer Shifts of Tl2Ba2Ca2Cu3O10

Tl 2 Ba 2 Ca 2 Cu 3 O 10 被报导是有在 Tl 2 Ba 2 C an1 CunO 2n+4 。在原子水平的 Cu 离子地点的直接信息为阐明是重要的超导性机制。Tl 2 Ba 2 Ca 2 Cu 3 O 10 用平均乐队差距模型被学习。计算结果证明 Cu (1 ) O 债券的 covalency 是 0.561，并且 Cu (2 ) O 的平均 covalency 是 0.296。M ?57 在 Tl 2 Ba 2 Ca 2 Cu 3 O 10 用化学包围因素被计算，由 covalency 和电子 polarizability 定义。这被验证为更低的做， Fe 代用品在 Cu (1 ) 地点处于良好的竟技状态的 Cu Fe 3+ 和 Fe 4+ ；为更高的做， Fe 3+ 和 Fe 4+ 离子占据 Cu (1 ) 和 Cu (2 ) 地点分别地。研究证明在光谱部件和实际的铜地点之间的通讯的决心由 M 占据了 ? ssbauer 原子核在化学契约参数的计算结果的帮助下被使更容易。

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n＋4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu（1）-O bond is 0.561, and the average covalency of Cu（2）-O is 0.296. Mossbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu （1） site in forms of Fe^3＋ and Fe^4＋; for higher doping, Fe^3＋ and Fe^4＋ ion occupies Cu（1） and Cu（2） site respectively. The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by MSssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.