Synthesis, crystal structure and magnetic properties of a new pillared perovskite La5Mo2.75V1.25O16

摘要

A new pillared perovskite compound La5Mo2.76(4)V1.25(4)O16, has been synthesized by solid-state reaction and its crystal structure has been characterized using powder X-ray and neutron diffraction. The magnetic properties of this compound have been investigated using SQUID magnetometry, and the magnetic structure has been studied using neutron diffraction data. A theoretical calculation of relative strengths of spin interactions among different magnetic ions and through different pathways has been performed using extended Huckel, spin dimer analysis. The crystal structure of this material contains perovskite-type layers that are connected through edge-sharing dimeric units of octahedra. The structure is described in space group C2/m with unit cell parameters a = 7.931(2)angstrom, b = 7.913(2)angstrom, c = 10.346(5)angstrom and beta = 95.096(5)degrees. The material shows both short-range ferrimagnetic correlations from similar to 200 to 110K and long-range antiferromagnetic order below T-c similar to 100 K. The magnetic structure was investigated by neutron diffraction and is described by k = (0 0 1/2) as for other pillared perovskites. It consists of a ferrimagnetic arrangement of Mo and V within the layers that are coupled antiferromagnetically between layers. This is the first magnetic structure determination for any Mo-based pillared perovskite. (C) 2008 Published by Elsevier Inc.