Abstract

Structural and magnetic properties of γ-Fe2O3 have been studied in isometric nanoparticles ranging from 3 to 14 nm with a narrow particle size distribution. Cation vacancy order is observed for particles larger than 5 nm in diameter giving rise to a cubic superstructure, while for the smallest particles these vacancies are disordered. All magnetic properties measured showed a strong dependence on the average crystallite size. For the ordered samples, saturation magnetization was found to decrease linearly with decreasing crystallite size due to a surface spin canting effect. However, a stronger decrease was observed in the disordered samples, suggesting that also an internal spin canting (cation vacancy order−disorder) has to be taken into account to explain the magnetic properties of nanoparticles. The room-temperature coercive field decreases with decreasing crystallite size; however at low temperatures, the coercivity increases as the size decreases, reaching values larger than 3000 Oe. A model to explain the magnetic properties of these particles considering both surface and order−disorder effects is proposed.

Keywords

Spin cantingCrystalliteCoercivityMaterials scienceCondensed matter physicsVacancy defectNanoparticleParticle sizeMagnetizationSuperstructureMagnetic nanoparticlesSaturation (graph theory)Nuclear magnetic resonanceMagnetic fieldNanotechnologyChemistryThermodynamicsPhysicsMetallurgyPhysical chemistry

Related Publications

Publication Info

Year
1999
Type
article
Volume
11
Issue
11
Pages
3058-3064
Citations
625
Access
Closed

External Links

View on DOI.org

Social Impact

Altmetric
PlumX Metrics

Social media, news, blog, policy document mentions

Citation Metrics

625
OpenAlex

Cite This

S. Veintemillas‐Verdaguer, Manuel Montero, Carlos J. Serna et al. (1999). Surface and Internal Spin Canting in γ-Fe<sub>2</sub>O<sub>3</sub> Nanoparticles. Chemistry of Materials , 11 (11) , 3058-3064. https://doi.org/10.1021/cm991018f

Identifiers

DOI
10.1021/cm991018f