Size Dependent Magnetic Properties and Cation Inversion in Chemically Synthesized MnFe2O4 Nanoparticles
MnFe{sub 2}O{sub 4} nanoparticles with diameters ranging from about 4 to 50 nm were synthesized using a modified coprecipitation method. X-ray diffractograms revealed a pure phase spinel ferrite structure for all samples. Transmission electron microscopy showed that the particles consist of a mixture of both spherical (smaller) and cubic (larger) particles dictated by the reaction kinetics. The Neel temperatures (T{sub N}) of MnFe{sub 2}O{sub 4} for various particle sizes were determined by using high temperature magnetometry. The {approx}4 nm MnFe{sub 2}O{sub 4} particles showed a T{sub N} of about 320 C whereas the {approx}50 nm particles had a T{sub N} of about 400 C. The high Neel temperature, compared with the bulk MnFe{sub 2}O{sub 4} T{sub N} of 300 C, is due to a change in cation distribution between the tetrahedral and octahedral sites of the spinel lattice. Results of extended x-ray absorption fine structure measurements indicate a systematic change in the cation distribution dependent on processing conditions.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 930659
- Report Number(s):
- BNL-81141-2008-JA; JAPIAU; TRN: US200901%%18
- Journal Information:
- Journal of Applied Physics, Vol. 101; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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