Acta Crystallographica Section A Foundations of Crystallography · 1998 · 549 citations · 0 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsCrystal StructureSolid State PhysicsCrystal LatticeCrystallographyStrongly Correlated Electron SystemsSuperconducting MaterialsX-ray CrystallographyX-ray DiffractionCritical TemperatureCuprate SuperconductorsHigh-temperature SuperconductivityHigh-temperature SuperconductorsSingle-crystal DiffractionSingle-crystal X-ray DiffractionSuperconducting Critical TemperatureX-ray Diffraction Analysis
The structures of superconducting Tl2Ba2CaCu2O8 (Tc ∼ 110 K) and YBa2Cu4O8 (Tc ∼ 70 K) were investigated by single-crystal X-ray diffraction techniques in a wide temperature range. Some of the structure parameters show anomalous behaviour in the vicinity of the critical temperature. The most pronounced structural change is the shift of the apical O atoms in CuO5 pyramids towards the CuO2 planes, indicating charge redistribution near Tc. This behaviour of the apical O atoms seems to be the common structural feature of hole-doped high-Tc superconductors. Another effect of charge redistribution at Tc concerns a very small decrease of in-plane Cu—O distances and/or O—O distances in CuO5 pyramids. Both effects represent an averaged structure response to charge (hole) redistribution upon the phase transition to the superconducting state.