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用EHT近似下紧束缚态方法讨论了BI-Sr-Ca-Cu-O体系超导体221相和232相的能带结构。结果表明底部刚好落在费米能级上的Bi6p能带很容易接受Cu-O面提供的载流子,使Cu-O面成为导电通带。232相比221相多一穿过费米能级的半满能带,是Tc(232相)远大于Tc(221相)的原因之一。
The band structure of phase 221 and phase 232 of the BI-Sr-Ca-Cu-O system superconductor was discussed by using the EHT approximation tight bound state method. The results show that the Bi6p band at the bottom of the Fermi level is easy to accept the carriers provided by the Cu-O plane, making the Cu-O plane conductive. One of the reasons that Tc (232 phase) is much larger than Tc (phase 221) is that the 232 has more half-full-band than the 221-phase through the Fermi level.