Synthesis and Magnetic Properties of Double Perovskite La_2BMnO_6 (B = Ni or Co) Nanoparticles

摘要

Double perovskite La_2BMnO_6 (B = Ni and Co) nanoparticles with average particle size of ～50 nm were synthesized using a facile, environmentally friendly, scalable molten-salt reaction at 700 °C in air. Their structural and morphological properties were characterized by x-ray diffraction and transmission electron microscopy. Their magnetic properties were evaluated using dc magnetic M-T and M-H, and ac magnetic susceptibility versus frequency, temperature, and field for the first time. The dc magnetization curves show paramagnetic-ferromagnetic transitions at T_C ～275 and 220 K for La_2NiMnO_6 (LNMO) and La_2CoMnO_6 (LCMO) nanoparticles, respectively, ac susceptibility revealed that the LCMO nanoparticles had a single magnetic transition indicative of Co~(2+)-O~(2-)-Mn~(4+) ordering, whereas the LNMO nanoparticles showed more complex magnetic behaviors suggesting a re-entrant spin glass.