6 research outputs found
Synthesis of Bio-Compatible SPION–based Aqueous Ferrofluids and Evaluation of RadioFrequency Power Loss for Magnetic Hyperthermia
Bio-compatible magnetic fluids having high saturation magnetization find immense applications in various biomedical fields. Aqueous ferrofluids of superparamagnetic iron oxide nanoparticles with narrow size distribution, high shelf life and good stability is realized by controlled chemical co-precipitation process. The crystal structure is verified by X-ray diffraction technique. Particle sizes are evaluated by employing Transmission electron microscopy. Room temperature and low-temperature magnetic measurements were carried out with Superconducting Quantum Interference Device. The fluid exhibits good magnetic response even at very high dilution (6.28 mg/cc). This is an advantage for biomedical applications, since only a small amount of iron is to be metabolised by body organs. Magnetic field induced transmission measurements carried out at photon energy of diode laser (670 nm) exhibited excellent linear dichroism. Based on the structural and magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of radiofrequencies
On the Synthesis and Characterisation of Magnetic Metal and Metal oxide Nanostructures
Department of Physics,
Cochin University of Science and Technolog
Cure Kinetics and Sorption Characteristics of Neoprene-Based Rubber Ferrite Composites
Rubber ferrite composites were prepared by incorporating nickel ferrite in a neoprene
rubber matrix. Kinetics of the cure reaction were determined from the rheometric torque
values and found to follow first-order kinetics. Analysis of the swelling behavior of
the rubber ferrite composites in toluene elucidates the mechanism of solvent penetration
and sorption characteristics, and reveals the extent of the physical interaction of
the ferrite particles with the neoprene rubber matrix. Mechanical properties of rubber
ferrite composites were determined, which support the reinforcing nature of nickel ferrite
to the neoprene rubber matrix. These results show that magnetic composites with
the required processing safety can be prepared economically by incorporating higher
amounts of nickel ferrite in the neoprene rubber matrixCochin University of Science and TechnologyInternational Journal of Polymeric Materials, 59:173–183, 201
A microwave absorber based on strontium ferrite–carbon black–nitrile rubber for S and X-band applications
Flexible and thin single layer microwave absorbers based on strontium ferrite–carbon black–nitrile rubber
composites have been fabricated employing a specific recipe and their reflection loss characteristics
were studied in the S (2–4 GHz) and X-bands (8–12 GHz). The incorporation of carbon black not only
reinforces the rubber by improving the mechanical properties of the composite but also modifies the
dielectric permittivity of the composite. Strontium ferrite when impregnated into a rubber matrix
imparts the required magnetic permeability to the composite. The combination of strontium ferrite
and carbon black can then be employed to tune the microwave absorption characteristics of the resulting
composite. The complex dielectric permittivity and permeability were measured by employing a cavity
perturbation technique. The microwave absorption characteristics of composites were modelled in that
an electromagnetic wave incident normally on the metal terminated single layer absorber. The influence
of filler volume fraction, frequency, absorber thickness on the bandwidth of absorption are discussed and
correlatedCochin University of Science and TechnologyComposites Science and Technology 82 (2013) 69–7
Evidence for intergranular tunnelling in polyaniline passivated α-Fe nanoparticles
Nanoparticles are of immense importance both from the fundamental and
application points of view. They exhibit quantum size effects which are
manifested in their improved magnetic and electric properties. Mechanical
attrition by high energy ball milling (HEBM) is a top down process for
producing fine particles. However, fineness is associated with high surface
area and hence is prone to oxidation which has a detrimental effect on the
useful properties of these materials. Passivation of nanoparticles is known to
inhibit surface oxidation. At the same time, coating polymer film on
inorganic materials modifies the surface properties drastically. In this work a
modified set-up consisting of an RF plasma polymerization technique is
employed to coat a thin layer of a polymer film on Fe nanoparticles produced
by HEBM. Ball-milled particles having different particle size ranges are
coated with polyaniline. Their electrical properties are investigated by
measuring the dc conductivity in the temperature range 10–300 K. The low
temperature dc conductivity (I–V ) exhibited nonlinearity. This nonlinearity
observed is explained on the basis of the critical path model. There is
clear-cut evidence for the occurrence of intergranular tunnelling. The results
are presented here in this paperCochin University of Science and TechnologyNanotechnology 17 (2006) 4765–477