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Chemical Bond Properties and Isomer Shifts of Tl2Ba2Ca2Cu3O10
Jin-ku Yu,Dong-chun Li,Fa-ming Gao
Author NameAffiliationE-mail
Jin-ku Yu College of Material Science and Engineering, State Key Lab Metastable Material Science Technology, Yanshan University, Qinhuangdao 066004, China  
Dong-chun Li College of Material Science and Engineering, State Key Lab Metastable Material Science Technology, Yanshan University, Qinhuangdao 066004, China  
Fa-ming Gao College of Material Science and Engineering, State Key Lab Metastable Material Science Technology, Yanshan University, Qinhuangdao 066004, China fmgao@ysu.edu.cn 
Abstract:
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. M(o)ssbauer 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 Fe3+ and Fe4+; for higher doping, Fe3+ and Fe4+ 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 M(o)ssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.
Key words:  Superconductor, Tl2Ba2Ca2Cu3O10, Chemical bond, M(o)ssbauer effect
FundProject:
Tl2Ba2Ca2Cu3O10的化学键性质和同质异能位移研究
于金库,李东春,高发明*
摘要:
在Tl2Ba2Can?1CunO2n+4 (n=1,2,3,4)系列超导性氧化物中, Tl2Ba2Ca2Cu3O10具有最高Tc值(125 K).利用电介质的平均能带模型计算了Tl2Ba2Ca2Cu3O10的局域化学键参数,得到Cu(1)-O键的共价性为0.561, Cu(2)-O键的平均共价性为0.296.应用化学环境因子计算了57Fe在Tl2Ba2Ca2Cu3O10中的穆斯堡尔同质异能位移,证实了57Fe在低掺杂时以Fe3+和Fe4+离子形式占据Cu(1)位置, 而在高掺杂时以Fe3+和Fe4+离子形
关键词:  超导体, 铊钡钙铜氧, 化学键, 穆斯堡尔效应
DOI:10.1360/cjcp2006.19(3).211.3
分类号: