Large tunability of Néel temperature by growth-rate-induced cation inversion in Mn-ferrite nanoparticles

• Published in: Applied physics letters Vol. 94; no. 11; pp. 113109 - 113109-3
• Main Authors: Yang, Aria, Chinnasamy, C. N., Greneche, J. M., Chen, Yajie, Yoon, Soack D., Hsu, Kailin, Vittoria, C., Harris, V. G.
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics 16-03-2009
• Subjects: CATIONS; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COPRECIPITATION; FERRITES; FLEXIBILITY; national synchrotron light source; NEEL TEMPERATURE; PARTICLE SIZE; SYNTHESIS; TUNING
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3099340

The tuning of Néel temperature by greater than 100 K in nanoparticle Mn-ferrite was demonstrated by a growth-rate-induced cation inversion. Mn-ferrite nanoparticles, having diameters from 4 to 50 nm, were synthesized via coprecipitation synthesis. The Néel temperature
(
T
N
)
increased inversely to the cation inversion parameter,
δ
(i.e., defined as
(
Mn
1
−
δ
Fe
δ
)
tet
[
Mn
δ
Fe
2
−
δ
]
oct
O
4
). Concomitantly,
T
N
increased with increased particle growth rate and particle size. These results unambiguously establish cation inversion as the dominant mechanism in modifying the superexchange leading to enhanced
T
N
. The ability to tailor
T
N
enables greater flexibility in applying nanoparticle ferrites in emerging technologies.