CAJ | 학술논문

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+离子形式分别占据Cu(1)和Cu(2)位置.结果表明,化学键理论计算有助于复杂晶体的穆斯堡尔谱的正确分析.
재Tl2Ba2Can-1CunO2n+4(n=1,2,3,4)계렬초도성양화물중,Tl2Ba2Ca2Cu3O10구유최고Tc치(125 K).이용전개질적평균능대모형계산료Tl2Ba2Ca2Cu3O10적국역화학건삼수,득도Cu(1)-O건적공개성위0.561,Cu(2)-O건적평균공개성위0.296.응용화학배경인자계산료57Fe재Tl2Ba2Ca2Cu3O10중적목사보이동질이능위이,증실료57Fe재저참잡시이Fe3+화Fe4+리자형식점거Cu(1)위치,이재고참잡시이Fe3+화Fe4+리자형식분별점거Cu(1)화Cu(2)위치.결과표명,화학건이론계산유조우복잡정체적목사보이보적정학분석.
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.