CHED 62 |
| Cobalt-substituted ferrite nanoparticles were synthesized by coprecipitation and using reverse micelles. ICP-OES verified the presence of cobalt in all samples. FTIR show bands characteristic of the metal-oxygen bond. Bands in 1725, 1459, and 1218 cm-1 were also observed for the samples synthesized by reverse micelles which were attributed to AOT bound to the particle. XRD confirmed the inverse spinel structure and showed a highly crystalline structure for the nanoparticles synthesized by coprecipitation. TEM shows a narrow size distribution for the particles synthesized using reverse micelles. SQUID showed coercivities higher than 8kOe at 5K, whereas at 300K the particles showed superparamagnetic behavior. The anisotropy constant was determined based on the Debye model for a magnetic dipole in an oscillating field. Anisotropy constant values in the order of ~106 kerg/cm3 were determined whereas anisotropy constants in the order of ~107 kerg/cm3 were calculated assuming Wt=1 at the temperature peak of the in-phase component of the susceptibility curve. Cobalt-substituted ferrite nanoparticles have been functionalized with dimercaptosuccinic acid (DMSA). Bands at 1600 and 1383 cm-1 were observed in FTIR confirming the COO-Me bound. DMSA-cobalt ferrite ferrofluid was observed to be stable in the pH range of 9.5 to 6.0 while uncoated ferrofluid was stable only in acidic medium. TGA, RAMAN, and DLS were also used to verify functionalization with DMSA. |
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NSF Partnership for Research and Education in Materials
1:30 PM-4:40 PM, Sunday, 10 September 2006 San Francisco Marriott -- Salon 11, Oral
Division of Chemical Education |