Enhanced Néel Temperature in Mn Ferrite Nanoparticles Linked to Growth-Rate-Induced Cation Inversion
Mn ferrite (MnFe2O4) nanoparticles, having diameters from 4 to 50 nm, were synthesized using a modified co-precipitation technique in which mixed metal chloride solutions were added to different concentrations of boiling NaOH solutions to control particle growth rate. Thermomagnetization measurements indicated an increase in Neel temperature corresponding to increased particle growth rate and particle size. The Neel temperature is also found to increase inversely proportionally to the cation inversion parameter, d, appearing in the formula (Mn1-dFed)tet[MndFe2-d]octO4. These results contradict previously published reports of trends between Neel temperature and particle size, and demonstrate the dominance of cation inversion in determining the strength of superexchange interactions and subsequently Neel temperature in ferrite systems. The particle surface chemistry, structure, and magnetic spin configuration play secondary roles.
- 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:
- 980192
- Report Number(s):
- BNL-93110-2010-JA; TRN: US201015%%1577
- Journal Information:
- Nanotechnology, Vol. 20
- Country of Publication:
- United States
- Language:
- English
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