Synthesis, characterization, and electrical properties of the series of oxides Ag5Pb2-xCuxO6 (0.0 ≤ x ≤ 0.5)

The synthesis and characterization of a series of complex silver-lead-copper oxides is presented. These compounds constitute a solid solution with formula Ag5Pb2-xCuO6, (0.0 less than or equal to x less than or equal to 0.5), where Pb (IV) cations are substituted by Cu(II) cations. The synthesis was carried out by coprecipitation of Ag(I), Pb(II), and Cu(II) nitrates in alkaline media and made use of excess Ag(I) as a sacrificial reagent to oxidize lead to Pb(IV). The structure of the series is that of the parent Ag5Pb2O6, with Cu(II) occupying part of the octahedral sites. This substitution induces interesting changes in the electric properties of the different members of the series, which range from metallic conductivity to semiconducting behavior. From Rietveld analysis for Ag5Pb1.5Cu0.5O6, the best fit is obtained for a model with Pb and Cu disordered over the octahedral site (Ag5Pb1.5Cu0.5O6, trigonal, P (3) over bar 1m, a=5.8306(9)Angstrom, c= 6.3430(6)Angstrom, V=187.37,Angstrom(3), Z=1, R-P=7.16, R-wp=9.26, R-expected = 5,88, R-Bragg = 3.94, x(2) = 2.48). (C) 2002 Elsevier Science.