Synthesis and electrical properties of Ba(Sn0.7Sb0.3)O-3

BaSn0.7Sb0.3O3 has been synthesized for the first time. This result is orig inal because up to now the solubility limit of the Ba(Sni-xSbx)O-3 series w as found to be x=0.2. The electronic carrier concentration is prevented fro m screening phonons via infrared reflectivity spectra. Whereas a transition from metal to superconductor behaviour is observed upon substituting Pb fo r Bi in the perovskite Ba(Pb,Bi)O-3 system, no similar transition was obser ved in the Ba(Sn,Sb)O-3 system, although these systems have the same struct ure. The phenomen of 3+/5+ disproportionation exists in both systems. The o ctahedra are occupied by cations exhibiting the same valence. The electroni c carrier concentration is similar but superconductivity is not observed in the Ba(Sn,Sb)O-3 system. The correlation between metallicity and structure is studied. (C) 2000 Elsevier Science Ltd. All rights reserved.