Publication Date:
2014-07-16
Description:
Double perovskite La 2-x Ca x CoMnO 6 (x = 0, 0.1, 0.2, 0.5) ceramics samples were synthesized by the standard solid-state reaction method. The crystal structures have been confirmed to be monoclinic perovskite structure with space group of P2 1 /n at room temperature by the powder x-ray diffraction (Cu-Kα). The grains of the samples are relatively dense and distribute in random directions from the scanning electron microscope patterns. Holes are doped into La 2 CoMnO 6 with the substitution of the Ca 2+ ions in La-site, and further lead to the valences of Mn ions and Co ions transforming from Mn 4+ and Co 2+ to Mn 3+ and Co 3+ , respectively. Ferromagnetic coupling of Mn 4+ -O 2– -Co 2+ and antiferromagnetic coupling of Mn 3+ -O 2– -Co 3+ are coexistent in La 2-x Ca x CoMnO 6 system, which correspond to two transitions existed in field-cooling magnetization versus temperature curves. Curie temperature of La 2-x Ca x CoMnO 6 system decreases with the increasing of Ca-substitution amount. The coexistence of different magnetic phases leads to the exchange bias effect.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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