RELATIONSHIP BETWEEN OXYGEN-CONTENT AND SUPERCONDUCTIVITY OF TL0.5PB0.5SR2CUOY (Y-APPROXIMATE-TO-5)

The electronic energy band structures of the Tl0.5Pb0.5Sr2CuOy (y appr oximate to 5) superconductor were calculated and the effect of the oxy gen content on its electronic structures was studied in the present pa per. The results show that the oxygen content has a great influence on its electronic structures. The moderate oxygen content causes the num ber of bands near the Fermi surface to increase and results in a sudde n change in the densities of states at the Fermi level E(f). The influ ence of the oxygen content on the electronic structures is mainly due to the peroxide pairs in the unit cell. The lower or higher oxygen con tent results in the decrease in the number of bands near E(f) and the densities of states at E(f), which is of no advantage to superconducti vity.