MnFe 2 O 4 nanoparticles thinly coated with oleic acid were successfully synthesized via a coprecipitation technique. Morphological analysis shows the co-existence of different nanoparticle assemblies such as dense agglomeration, chain clustering, and random clustering, the effect of which was then reflected in the FTIR spectrum and magnetization behavior of the MnFe 2 O 4 nanoparticles. Induction heating study collectively discusses the association of dipolar energy and magnetic anisotropy energy with the applied field intensity in various nanoparticle clustering systems. The highest applied field intensity (H 250 : 14.98 kAm −1 ) at a nanoparticle concentration of 2 mg ml −1 shows a maximum specific absorption rate of 98.37 W g −1 , which is attributed to the effect of threshold field amplitude surpassing the dipolar field energy. The nanoparticle clustering due to an interdigitated effect and chain clustering can effectively contribute to heat generation via Neelian and hysteresis loss mechanism at a suitable high field intensity.

Crystallographic inversion induced shift of resonance frequency in zinc ferrite nanoparticle (ZF-NP) samples is studied here. ZF-NP samples were synthesized by a solution-based, low-temperature (<200 °C), microwave-assisted solvothermal (MAS) process. Owing to the far-from-equilibrium processing condition, the MAS process produces a very high degree of crystallographic inversion, δ=0.61, in the as-synthesized nanocrystallites. A rapid thermal annealing (RTA) technique was adopted to tune-down crystallographic inversion without altering the crystallite sizes in annealed samples. The crystal structures, particle shapes, and compositions of the nanocrystalline samples were characterized by XRD, SEM and Raman spectroscopy. The samples are phase-pure, with particle size in the range 8-16 nm and their compositions are stoichiometrically accurate. The resonance phenomena in 1 to 10 GHz frequency range was measured by analyzing the impedance mismatch of a microstrip line with the magnetic material loaded on to it. The RTA protocol enables tuning of the resonance phenomena in the ZF-NC samples above 6 GHz with tunable range of ∼500 MHz

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We report a high performance magnetic nanoparticle as hyperthermic agent under low applied field and frequency. CTAB (cetyltrimethylammonium bromide)-coated NixZn1-xFe2O4 nanoparticles of average particle size < 25 nm with various...