Structural and magnetic properties of the anion-deficient LaVO_3-δ

The anion deficient LaVO_3-δ (δ = 0.08) was prepared by solid state reactions using V₂O₃ and pre-dried La₂O₃ in an evacuated induction furnace. The oxygen content was estimated by thermogravimetric analysis (TGA). Rietveld profile analysis of powder X-ray diffraction data shows that this sample adopts an orthorhombically distorted perovskite structure, isostructural with GdFeO₃; space group Pnma, a = 5.5509(1), b = 7.8441(2), c = 5.5513(s) A ̊. Four probe resistivity measurements indicates that LaVO_3-δ is semiconducting over the experimental temperature range. The magnetic properties of LaVO_3-δ are strongly dependent on the sample cooling history. LaVO_3-δ undergoes a paramagnetic to antiferromagnetic transition at ca. 140 K under zero-field-cooled condition. When cooled in a magnetic field of H_appl ≤ 5 kG, however, the anomalous diamagnetic behaviour is observed below ca. 140 K. These properties are discussed in terms of the structure-property relationship, and comparisons are made to the previous results on the stoichiometric LaVO₃.