Polarized neutron study of the magnetization density distribution within a CoFe/sub 2/O/sub 4/ colloidal particle (magnetization density in a colloidal CoFe/sub 2/O/sub 4/ crystallite)

Technical Report · Sat Jan 01 00:00:00 EST 1983

DOI:https://doi.org/10.2172/6305993· OSTI ID:6305993

Nunes, A C; Majkrzak, C F; Berkowitz, A E

Magnetization and Moessbauer data suggest that a magnetically anomalous region exists within finely divided CoFe/sub 2/O/sub 4/ particles when coated with oleic acid. We have undertaken an x-ray and a polarized neutron powder diffraction study of these samples with and without the surfactant coating in an attempt to locate and characterize this anomalous zone. The shape of neutron scans of the (4,0,0) reflection are independent of polarization indicating that the reflecting crystallites are uniformly magnetized. Magnetization calculated from the peak flipping ratio is characteristic of uncoated rather than coated particles in both cases. Scan widths of both x-rays and neutrons are narrower for the sample from which the chemisorbed surfactant has been largely removed indicating an increase in the size of the coherent lattice of a crystallite. These observations are consistent with the existence of a highly strained surface layer roughly 10 Angstroms thick characterized by pinned spins associated with the presence of oleic acid, which relaxes to a more normal lattice structure upon boiling off the surfactant.

• Research Organization: Rhode Island Univ., Kingston (USA). Dept. of Physics; Brookhaven National Lab. (BNL), Upton, NY (United States); General Electric Co., Schenectady, NY (USA). Corporate Research and Development Center
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6305993
• Report Number(s): BNL-32685; CONF-830619-1; ON: DE83010015
• Resource Relation: Conference: 3. international conference on magnetic fluids, Bangor, UK, 28 Jun 1983
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT COMPOUNDS
MAGNETIZATION
FERRATES
COATINGS
COLLOIDS
EXPERIMENTAL DATA
NEUTRON DIFFRACTION
OLEIC ACID
PARTICLES
POLARIZED BEAMS
X-RAY DIFFRACTION
BEAMS
CARBOXYLIC ACIDS
COHERENT SCATTERING
DATA
DIFFRACTION
DISPERSIONS
INFORMATION
IRON COMPOUNDS
MONOCARBOXYLIC ACIDS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
360603* - Materials- Properties