Vijayaraghavan, R and Rangavittal, N and Kulkarni, GU and Grantscharova, Emilia and Row, Guru TN and Rao, CNR (1991) Structure and superconducting properties of Tl1?yPbyY1?xCaxSr2Cu2O7star, open: Dependence of Tc on hole concentration. In: Physica C: Superconductivity, 179 (1-3). pp. 183-190.
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Structure and superconducting properties of Tl1?yPbyY1?xCaxSr2Cu2O7 (y=0.0, 0.1, 0.25 and 0.5) , derived from the parent insulator TlYSr2Cu2O7, have been investigated for different values of x. XANES studies show Pb to be in the 4+ state while Tl is in the 3+ state, suggesting thereby that in this series, (x?y) approximately corresponds to the hole concentration. The in-plane Cu---O distance decreases with increase in x for all values of y. The apical Cu---O distance as well as the Tl(Pb)---O(2) distance show anomalies at x=0.5 in the series with y=0.25; at this composition, Tc also reaches a maximum. In general, the composition (value of x) at which the Tc of Tl1?yPbyY1?xCaxSr2Cu2O7 reaches a maximum depends on the Pb content and the maximum Tc itself increases with increase in y, reaching a value of 105 K at y=0.5. More interestingly, a maximum Tc occurs at an (x?y) value of not, vert, similar0.25, which is close to the hole concentration at maximum Tc in other cuprate superconductors containing two CuO2 layers.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier science.|
|Department/Centre:||Division of Chemical Sciences > Solid State & Structural Chemistry Unit|
|Date Deposited:||30 Nov 2010 13:16|
|Last Modified:||30 Nov 2010 13:16|
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