Synthesis, Crystal Structure, Electric and Magnetic Properties of LaVO 2.78 N 0.10

摘要

Perovskite-type LaVO2.78N0.10 powder was synthesized by thermal ammonolysis of the oxide precursor LaVO4. By X-ray, neutron, and electron diffraction an orthorhombic crystal structure with space group Pnma was identified. XANES spectra showed that the oxidation state of vanadium changes from 5+ in LaVO4 to approximately 3+ in LaVO2.78N0.10. The temperature dependence of the electrical conductivity revealed an Arrhenius-type behavior with an activation energy of 0.103 eV in the temperature range of 119–302 K indicating that the conduction process is thermally activated band transition. Based on the positive Seebeck coefficient, holes were identified as the dominant charge carriers in the temperature range of 100–302 K. Both the Seebeck coefficient and the thermal conductivity showed an anomaly at 138 K, which is attributed to the Néel temperature for antiferromagnetic ordering according to magnetic susceptibility measurements.