On the transport properties of the solid solution Sr1−xLaxPbO3−δ (0 ⩽ x ⩽ 0.15)

✍ Scribed by B. Hadjarab; S. Bassaid; A. Bouguelia; M. Trari

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 206 KB
• Volume: 439
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2006.02.006

✦ Synopsis

Mixed valencies system Sr 1Àx La x PbO 3Àd (0 6 x 6 0.15) has been prepared by solid state reaction at 900 °C. All solutions crystallize in a distorted perovskite structure and were carefully examined by chemical analysis and X-ray diffraction. The La 3+ -substitution was checked via the linear dependence of lattice constants on x-value, i.e. Vegard's law. The expansion of the unit cell volume involves a simultaneous increase of all the parameters. The magnetic susceptibilities are slightly temperature dependent, dominated by core diamagnetism giving an effective mass m * of $9. The transport properties were investigated from 300 K down to liquid helium. The resistivity was found to change markedly with the rate substitution x and the oxides behave as degenerate semi-conductors with very weak activation energies. The insulating-metal transition can thus be considered of Anderson type attributed to random potential as lanthanum is substituted for strontium. The electric balance comes also from departure of oxygen and would imply a simultaneous reduction Pb 4+/2+ . The electron mobility is thermally activated with a temperature independent carrier concentration.