Electron doping effect on structural and magnetic phase transitions in Sr2-xNdxFeMoO6 double perovskites

Polycrystalline Sr2-xNdxFeMoO6 (x = 0.0 0.1. 0.2. 0.4) materials have been synthesized by a citrate co-precipitation method and studied by neutron powder diffraction (NPD) and magnetization measurements. Rietveld analysis of the temperature-dependent NPD data shows that the compounds (x = 0.0 0.1, 0.2) crystallize in the tetragonal symmetry in the range 10-400 K and converts to cubic symmetry above 450 K. The unit cell volume increases with increasing Nd3+ concentration, which is in electronic effect in order to change the valence state of the B-site cations. Antisite defects at the Fe-Mo sublattice increases with the Nd3+ doping. The Curie temperature was increased from 430 K for x = 0 to 443 K for x = 0.4. The magnetic moment of the Fe-site decreases while the Mo-site moment increases with electron doping. The antiferromagnetic arrangement causes the system to show a net ferrimagnetic moment. (C) 2006 Elsevier Inc. All rights reserved.