Size Effects on Gamma Radiation Response of Magnetic Properties of Barium Hexaferrite Powders

Journal Article · Thu Dec 08 00:00:00 EST 2011 · Journal of Applied Physics, 110(11):Article No. 113912

DOI:https://doi.org/10.1063/1.3665769· OSTI ID:1031422

McCloy, John S.; Kukkadapu, Ravi K.; Crum, Jarrod V.; Johnson, Bradley R.; Droubay, Timothy C.

Little is currently known about the effects of gamma-ray irradiation on oxide magnet materials. In particular, the effect of particle size on radiation susceptibility was investigated. Two commercial powders of BaFe12O19 were thoroughly characterized, then exposed to 1 MGy of gamma radiation from a 60Co source. AC susceptibility and DC magnetometry and Mössbauer spectroscopy were performed after irradiation and compared to pre-irradiated measurements. DC magnetization and AC susceptibility decreased for both samples with the relative change of DC magnetization being larger for the micrometer-sized particles and the relative change of the AC susceptibility being larger for the nanometer-sized particles. Mössbauer spectroscopy indicated a decrease in both the hyperfine fieldsand in the distribution of hyperfine fields for each Fe site, particularly in the larger particle sample. Decreases in susceptibility are believed to be due to recrystallization of the particles and redistribution of an amorphous component, in the bulk or on the surface, and consequent reduction in the particle magnetic moment. This radiation damage mechanism is different than that seen in previous studies of neutron and heavy ion irradiation of BaFe12O19.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1031422
• Report Number(s): PNNL-SA-80909; JAPIAU; 42302; 400403909; TRN: US1200099
• Journal Information: Journal of Applied Physics, 110(11):Article No. 113912, Vol. 110, Issue 11; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
74 ATOMIC AND MOLECULAR PHYSICS
BARIUM
DISTRIBUTION
GAMMA RADIATION
HEAVY IONS
IRRADIATION
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MAGNETIZATION
MAGNETS
MOESSBAUER EFFECT
NEUTRONS
OXIDES
PARTICLE SIZE
RADIATIONS
RECRYSTALLIZATION
Barium hexaferrite
ionizing radiation
AC susceptibility
Mössbauer
Environmental Molecular Sciences Laboratory