Distribution of electron density in BaPb 1− xBi xO 3 evidenced by 207Pb and 17O NMR

Abstract

The inhomogeneous magnetic broadening of the 17O and 207Pb NMR spectra resulting from a distribution of the Knight shifts was studied in the metallic phase of BaPb 1− x Bi x O 3 oxides (0⩽ x⩽0.33). It was shown that Bi atoms, which are randomly incorporated in the parent BaPbO 3, give rise to an increased spin density of carriers within the two first cation shells. The percolative overlap of these areas is expected for superconducting compositions ( x>0.1).