Synthesis and characterization of FePt nanoparticles and FePt nanoparticle/SiO2-matrix composite films

• Published in: Journal of sol-gel science and technology Vol. 64; no. 2; pp. 269 - 275
• Main Authors: Zhang, Jun-Long, Kong, Ji-Zhou, Li, Ai-Dong, Gong, You-Pin, Guo, Hai-Rong, Yan, Qing-Yu, Wu, Di
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.11.2012; Springer; Springer Nature B.V
• Subjects: Annealing; Ceramics; Chemistry; Chemistry and Materials Science; Coalescing; Coercivity; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Exact sciences and technology; General and physical chemistry; Glass; Grain growth; High temperature; Inorganic Chemistry; Intermetallic compounds; Iron; Iron compounds; Materials Science; Morphology; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Order parameters; Organic chemistry; Original Paper; Phase transitions; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Platinum compounds; Silicon dioxide; Sol-gel processes; SiO; 1; phase FePt; Monodisperse particle; Sol–gel; matrix; Composite film; Binary compound; Growth; Nanoparticle; Iron; Superparamagnetism; High temperature; Silica; Phase transitions; Aggregation; Characterization; Sol―gel; Synthesis; Platinum; Ordering; Polyol; Structure; Composition; Annealing; L1; Transition metal; Silicon oxides; Sol gel process; Morphology; Monodispersed particle; Coalescence; Long range order
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-010-2373-8

Superparamagnetic face-centered cubic (fcc) FePt nanoparticles were synthesized using a polyol process. The effect of reaction temperature and molar ratio of Fe(CO) 5 to Pt(acac) 2 on the structure, composition and morphology of nanoparticles has been investigated. The optimum processing condition has been obtained for producing well-monodisperse fcc-phase FePt nanoparticles with the 2:1 molar ratio of Fe-Pt at 220 °C. In order to circumvent the problem of FePt particle coalescence during high temperature annealing for the L 1 0 ordering, FePt nanoparticle/SiO 2 -matrix composite films have been fabricated by sol–gel method. The experimental results confirm that the amorphous SiO 2 matrix effectively inhibits the grain growth and particle aggregation during 700 °C annealing for 1 h. Well-monodisperse face-centered tetragonal (fct) FePt particles embedded in the SiO 2 matrix can be obtained with the long-range chemical order parameter S of ~0.74, indicating partially ordered L 1 0 phase transition in FePt/SiO 2 composite films. The FePt/SiO 2 system exhibits a hysteretic behavior with smaller coercive field of 1,450 Oe. The incomplete phase transition from cubic deredat height maxsium ( A 1 -disordered phase to tetragonal L 1 0 -ordered phase) might be responsible for it.