Tuning Pb content in High-Tc Bi2Sr2CaCu2Oy superconductors studied by X-ray absorption near-edge structure spectroscopy

Abstract

The variation of hole concentration within the CuO 2 planes via tuning Pb content in (Bi 2-x Pb x )Sr 2 CaCu 2 O y (0.2 ≤ x < 0.6) has been investigated by X-ray absorption near-edge structure (XANES) spectroscopy using synchrotron radiation. The profile of XANES spectra indicated that Pb can be incorporated into Bi-2212 phase under nitrogen atmosphere around x = 0.6. However, after annealing the nitrogen-sintered samples in oxygen, Pb solubility is found to be decreased only up to x = 0.2 in (Bi 2-x Pb x )ST 2 CaCu 2 O y , showing that compounds with high Pb content are more stable under oxygen-free armosphere.