Magnetization enhancement in magnetite nanoparticles capped with alginic acid

Abstract

We report on the effect of alginic acid capping on the behavior of magnetite nanoparticles. The capped nanoparticles exhibit improved crystalline structure of the surface which leads to an enhanced magnetization. The improved structure facilitates quantization of spin-wave spectrum in the finite size nanoparticles and this in turn is responsible for unconventional behavior at low temperatures. In electron magnetic resonance these anomalies are manifested as an unusual increase in the resonant field H r (T) and as a maximum of the spectroscopic splitting g eff parameter at low temperatures. This unconventional behavior leads also to pronounced upturn of magnetization at low temperatures and a deviation from the Bloch law M(T)~T 3/2 .

Synthesis, Characterization, and Magnetic Properties of Pure and EDTA-Capped NiO Nanosized Particles

“…However, the magnetization, and , of EDTAcapped NiO nanoparticles is enhanced as compared to that of the pure NiO nanoparticles because of bonding to EDTA. Such capping recovers the surface magnetization of the nanoparticles [42]. From Table 1, it is clear that < 0.5 for all samples indicating that the particles interact by magnetostatic interaction and the anisotropy decreases in crystal lattice [37,43].…”

A facile one-pot synthesis of poly(acrylic acid)-functionalized magnetic iron oxide nanoparticles for suppressing reactive oxygen species generation and adsorption of biocatalyst

“…The saturation of magnetization (M s ) 51.6 emug −1 for PAA1-functionalized IONPs is slightly higher than that of the bare IONPs (49 emug −1 ). This enhancement in M s is due to the improvement in the uniformity of surface property and colloidal stability of the IONPs via chemical modification with carboxylate moieties of PAA [46]. Besides, the bare surface is very prone to air oxidation during synthesis, purification and storage resulting so called magnetic dead-layer on the outer surface of IONPs, which reduces the M s value.…”

Anchoring Fe3O4 nanoparticles in a reduced graphene oxide aerogel matrix via polydopamine coating

“…The saturation magnetization was found to be 38.2 emu/g, 30.5 emu/g and 36.9 emu/g for rGO-Fe 3 O 4 , rGO-PDA@Fe 3 O 4 and c-rGO-PDA@Fe 3 O 4 aerogel samples, respectively. It was generally expected that covering the Fe 3 O 4 nanoparticles with an organic (PDA) shell will increase the magnetization of the samples [61], thanks to the protection of the magnetite surface from an environmental oxidation [62–64]. However, the saturation magnetization of rGO-PDA@Fe 3 O 4 with respect to the rGO-Fe 3 O 4 was decreased, which is due to additional contribution of PDA to the sample volume [65].…”