Magnetic Properties of the Double Perovskites LaPbMSbO6 (M=Mn, Co, and Ni)

D. G. FRANCO; R. E. CARBONIO; G. NIEVA

Workshop; X--LATIN AMERICAN WORKSHOP ON MAGNETISM AND MAGNETIC MATERIALS; 2013

New double perovskites LaPbMSbO6, where M2+ = Mn2+, Co2+, and Ni2+, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000C. All samples are monoclinic, space group P21/n, as it is observed from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M and Sb among the two octahedral sites have 3% of disorder for M2+= Ni2+, whereas for M Mn and Co less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M through super-superexchange paths M2+ - O2- - Sb5+ - O2- - M2+. Transition temperatures are low: 8, 10 and 17 K for Mn , Co , and Ni respectively, as a consequence of the relatively long distances between the magnetic ions M2+. Besides, for LaPbMnSbO6 a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder would give additional and shorter interaction paths: superexchange Mn2+ - O2- - Mn2+.