Seeded Growth of Ferrite Nanoparticles from Mn oxides : Observation of Anomalies in Magnetic Transitions
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Biological and Environmental Sciences and Engineering (BESE) Division
Chemical Science Program
Physical Sciences and Engineering (PSE) Division
Permanent link to this recordhttp://hdl.handle.net/10754/558454
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AbstractA series of magnetically active ferrite nanoparticles (NPs) are prepared by using Mn oxide NPs as seeds. Verwey transition is identified in Fe3O4 NPs with an average diameter of 14.5 nm at 96 K, where a sharp drop of magnetic susceptibility occurs. In MnFe2O4 NPs, spin glass-like state is observed with the decrease of magnetization below the blocking temperature due to the disordered spins during the freezing process. From these MnFe2O4 NPs, MnFe2O4@MnxFe1-xO core-shell NPs are prepared by seeded growth. The structure of core is cubic spinels (Fd-3m), and shell is composed of iron-manganese oxide (MnxFe1-xO) with a rock salt structure (Fm-3m). Moiré fringes appear perpendicular to <110> directions on the cubic shape NPs through the plane-matched epitaxial growth. These fringes are due to the difference in their lattice spacings between MnFe2O4 and MnxFe1-xO. Exchange bias is observed in these MnFe2O4@MnxFe1-xO core-shell NPs with an enhanced coercivity as well as the shift of hysteresis along the field direction.
CitationSeeded Growth of Ferrite Nanoparticles from Mn oxides : Observation of Anomalies in Magnetic Transitions 2015 Phys. Chem. Chem. Phys.
PublisherRoyal Society of Chemistry (RSC)
JournalPhys. Chem. Chem. Phys.