|Arrays of magnetic nanoparticles
capped with alkylaminesP JOHN THOMAS, P SARAVANAN, G U KULKARNI
and C N R RAO*
Chemistry and Physics of Materials Unit,
Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
Abstract.Magnetic metal and metal oxide nanoparticles capped with alkylamines have been synthesized and characterized by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray analysis and magnetization measurements. Core-shell Pd--Ni particles with composition, Pd561 Ni3000, (diameter ~3.3 nm) are superparamagnetic at 5 K and organize themselves into two-dimensional crystalline arrays. Similar arrays are obtained with Pd561Ni3000Pd1500 nanoparticles containing an additional Pd shell. Magnetic spinel particles of g-Fe2O3, Fe3O4 and CoFe2O4 of average diameters in the 4--6 nm range coated with octylamine are all supermagnetic at room temperature and yield close-packed disordered arrays. Relatively regular arrays are formed by dodecylamine-capped Fe3O4 nanoparticles (~8.6 nm diameter) while well-ordered hexagonal arrays were obtained with octylamine-covered Co3O4 nanoparticles (~4.2 nm diameter).
Keywords: Self-assembly; magnetic nanoparticles..
Pacs Nos. 81.16.D; 81.07.Bc; 81.16.B
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