Synthesis and properties of the double perovskites La2NiVO6, La2CoVO6, and La2CoTiO6

摘要

The double perovskites La2CoVO6, La2CoTiO6, and La2NiVO6, are described. Rietveld fitting of neutron and powder X-ray diffraction data show La2NiVO6 and La2CoVO6 to have a disordered arrangement of B-cations whereas La2CoTiO6 shows ordering of the B-cations (with similar to 5% Co/Ti inversion). Curie Weiss fits to the linear region of the 1/chi plots reveal Weiss temperatures of -107, -34.8, and 16.3 K for La2CoVO6, La2CoTiO6, and La2NiVO6, respectively, and magnetic transitions are observed. La2CoTiO6 prepared by our method differs from material prepared by lower-temperature routes. A simple anti ferromagnetic spin model is consistent with the data for La2CoTiO6. These compounds are semiconductors with bandgaps of 0.41 (La2CoVO6), 1.02 (La2CoTiO6) and 0.45 eV (La2NiVO6). (c) 2006 Elsevier Inc. All rights reserved.