Structural and Magnetic Properties of FePt/SiO{sub 2} Core/Shell Nanoparticles

Journal Article · Fri Mar 15 04:00:00 EDT 2019 · Journal of Superconductivity and Novel Magnetism

DOI:https://doi.org/10.1007/S10948-018-4679-7· OSTI ID:22919586

Hua, Jie; Cheng, Haibo; Zhang, Kewei; Zhang, Yumei; Li, Haibo ^[1]

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1. Jilin Normal University, Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education (China)

The disorder-order phase transition of FePt/SiO{sub 2} core/shell nanoparticles (NPs) induced by rapid thermal annealing was investigated. The FePt/SiO{sub 2} NPs were synthesized using FePt cores as seeds. For as-prepared FePt/SiO{sub 2} NPs, the average size of the FePt core and the thickness of the SiO{sub 2} shell are about 4.8 and 1.2 nm respectively, and the FePt NPs exhibit a disordered fcc structure. The FePt core NPs show obvious phase transformation from a disordered to an ordered structure after they were annealed at 600 °C for 2 min. Moreover, increasing annealing time can promote effectively the formation of the ordered fct-FePt phase. The relatively large coercivity H{sub c} is obtained for FePt NPs with a thicker SiO{sub 2} shell. The H{sub c} decreases firstly with decreasing temperature from 300 to 100 K and then increases from 100 to 10 K, which is ascribed to the coexistence of magnetically hard fct-FePt and magnetically soft fcc-FePt in the sample, and the incomplete exchange coupling between the hard and soft magnetic phases.

• OSTI ID: 22919586
• Journal Information: Journal of Superconductivity and Novel Magnetism, Journal Name: Journal of Superconductivity and Novel Magnetism Journal Issue: 3 Vol. 32; ISSN 1557-1939
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ANNEALING
BINARY ALLOY SYSTEMS
COERCIVE FORCE
FCC LATTICES
IRON COMPOUNDS
MAGNETIC PROPERTIES
NANOPARTICLES
PHASE TRANSFORMATIONS
PLATINUM COMPOUNDS
SILICON OXIDES
THICKNESS