Magnetic response of NiFe2O4 nanoparticles in polymer matrix

Abstract

We report the magnetic properties of magnetic nano-composite, consisting of different quantity of NiFe 2 O 4 nanoparticles in polymer matrix. The nanoparticles exhibited a typical magnetization blocking, which is sensitive on the variation of magnetic field, mode of zero field cooled/field cooled experiments and particle quantity in the matrix. The samples with lower particle quantity showed an upturn of magnetization down to 5 K, whereas the blocking of magnetization dominates at lower temperatures as the particle quantity increases in the polymer. We examine such magnetic behaviour in terms of the competitive magnetic ordering between core and surface spins of nanoparticles, taking into account the effect of inter-particle (dipole-dipole) interactions on nanoparticle magnetic dynamics.

Mechanical alloyed Ho3+ doping in CoFe2O4 spinel ferrite and understanding of magnetic nanodomains

“…The squareness ratio (M R /M S : ranging from 0.115 to 0.435) is well below of the typical value $1 for single domain isolated ferromagnetic particles where spins are exchange interacted and $0.5 for randomly oriented uniaxial anisotropic ferromagnetic particles [11,28]. The deviation of M R /M S from typical single domain class may be assigned to the interactions among grains [29][30][31], which are affected by core-shell structure of grains and grain size distribution in the material. For a ferromagnetic grain, we define the well spin ordered central part as the core and the surrounding disordered part as the shell (grain boundary).…”

“…The MZFC at 1 kOe S115 S95 S80 S100 S105 S110 S120 M (T)/M(100 K) T(K) respectively [8]. This could be the indication that magnetic grains are forming strongly interacting clusters, which showed a rapid increase in ferromagnetic moment on decreasing the temperatures below T C [22,[31][32][33]. At the same time, intergrains interactions are increasing below the irreversible temperature (T irr ), which is effectively increasing the cluster size (effective volume of magnetic particles).…”

Tailoring the performance of magnetic elastomers containing Fe2O3 decorated carbon nanofiber

“…The decline in mechanical properties has been attributed to weak adhesion between the magnetic llers and the elastomer matrix. [7][8][9] To improve the interfacial interaction between the magnetic ller and the polymer matrix, the surface energy of the llers must be greater than or equal to the surface energy of the polymer. Large sized magnetic particles exhibit a small intrinsic surface energy, and are apparently unable to form strong bonds with the elastomers.…”

Influence of mixed sulfur/peroxide curing system and thermo-oxidative ageing on the properties of rubber magnetic composites

“…The results showed that although the incorporation of magnetic fillers in rubber matrices leads to the preparation of composite materials with improved magnetic properties, physical-mechanical properties were usually deteriorated. The reason can be attributed to the weak adhesion between magnetic fillers and the rubber matrix [16][17][18]. Therefore, the aim of the present study was the preparation of rubber magnetic composites based on EPDM rubber matrix and strontium ferrite, by applying of mixed sulfur and peroxide curing systems.…”