Neutron diffraction and X-ray absorption study of Ag5Pb2O6

Neutron diffraction and X-ray absorption measurements were carried out for a silver–lead oxide Ag5Pb2O6. The powder neutron diffraction patterns could be fitted to the trigonal image structure, as was found by X-ray diffraction. From the bond-valence-sum (BVS) analysis, the valences of the Ag and Pb ions were estimated to be about 1+ and 3.7+, respectively. The X-ray absorption measurements indicated that the ionic state of Ag is close to 1+, while that of Pb stands between 3+ and 4+. The deviation of the valence of the Pb ion from 4+ suggests a contribution of Pb orbitals to the metallic conduction as well as the possible superconductivity of this material, consistently with a recent band-structure calculation.