Materials Research Bulletin, Vol.44, No.6, 1261-1264, 2009
Curie temperature enhancement in partially disordered Sr2FeReO6 double perovskites
Two samples of the double perovskite Sr2FeReO6 have been synthesized by (1) soft-chemistry procedures and (2) high-pressure methods. The sample prepared by a soft-chemistry technique presents 75% of Fe/Re cationic order whereas the one prepared by the application of high external pressure generates a complete Fe/Re cationic order. Both materials have been characterized by X-ray diffraction, neutron powder diffraction and magnetic measurements. The magnetic properties of both oxides have been compared. observing that the specimen prepared via soft-chemistry procedures presents an enhanced Curie temperature of 445 K, although the sample prepared under high-pressure techniques displays a superior saturation magnetization. This behavior is explained as a consequence of the presence. in the partially disordered sample, of Fe-rich islands containing strong Fe-O-Fe antiferromagnetic couplings, able to nucleate and lock the ferromagnetic interactions of the ordered regions, thus increasing the global Curie temperature of the partially disordered material. (C) 2009 Elsevier Ltd. All rights reserved.