Cationic distribution and spin canting in CoFe₂O₄nanoparticles

Abstract

CoFe(2)O(4) nanoparticles (<linear span>D(NPD)<linear span> ~6 nm), prepared by a thermal decomposition technique, have been investigated through the combined use of dc magnetization measurements, neutron diffraction, and (57)Fe Mössbauer spectrometry under high applied magnetic field. Despite the small particle size, the value of saturation magnetization at 300 K (M(s) ͠= 70 A m(2) kg(-1)) and at 5 K (M(s) ͠= 100 A m(2) kg(-1)) are rather close to the bulk values, making the samples prepared with this method attractive for biomedical applications. Neutron diffraction measurements indicate the typical ferrimagnetic structure of the ferrites, showing an inversion degree (γ(NPD) = 0.74) that is in very good agreement with cationic distribution established from low temperature (10 K) Mössbauer measurements in high magnetic field (γ(moss) = 0.76). In addition, the in-field Mössbauer spectrum shows the presence of a non-collinear spin structure in both A and B sublattices. The results allow us to explain the high value of saturation magnetization and provide a better insight into the complex interplay between cationic distribution and magnetic disorder in ferrimagnetic nanoparticles.

Solvothermal synthesis of MnFe2O4 nanoparticles: The role of polymer coating on morphology and magnetic properties

“…In addition, the high surface to volume ratio and type of nanoparticles can strongly influence the magnetic properties (i.e., surface anisotropy, saturation magnetization). Magnetism at the particle's surface is governed by a breaking of the lattice symmetry; which induces changes in the topology of the surface magnetic moments and consequently in the exchange integrals (through a change of superexchange angles and/or distances between moments), thus leading to an increase of anisotropy (i.e., a surface component) and a decrease in saturation magnetization [4,5]. Moreover, several authors have shown that the interaction between polymer molecules and surface atoms can induce modifications in the NPs magnetic properties [6,7].…”

Exchange spring like magnetic behavior in cobalt ferrite nanoparticles

“…The physical properties of these nanoparticles can also be easily tailored by controlling its microstructure and enabling them for many applications [13][14][15]. The sizes of the nanoparticles [14,16], morphology [7,13], size distribution [17][18][19], packing density [20], intergranular exchange interaction [21][22][23], and cation distribution [24,25] are some of the factors which are responsible for the modified magnetic properties in the nanomaterials. Among these, grain/particle size and their distributions are most of the important factors governing the magnetic properties in the nanomaterials.…”

Crystalloquasichemical Model of Spinel CoFe2O4 Formation, Obtained by Chemical co-Precipitation Method

“…Будучи перспективним магнітним і електричним резистивним матеріалом, CoFe 2 O 4 знайшов широке застосування у запам'ятовуючих пристроях, магнітоелектричних перетворювачах, датчиках газу тощо [1][2][3][4][5][6][7][8]. Проте на сьогодні не описано механізм його утворення, зокрема з позицій взаємодії дефектних фаз.…”