Browsing by Author "Revathi, V"

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    Relaxor-like ferroelectric behaviour favoured by short-range B-site ordering in 10% Ba2+ substituted MgFe2O4
    (2016-01-07T11:35:59Z) Chithra, Lekha; Ramesh; Revathi, V; Subramanian, V
    Using the molten salt method, pristine and Ba2+ substituted MgFe2O4 are prepared. The relaxor-like behaviour observed in the dielectric dispersion indicates the existence of B-site short-range ordering with the local P4122/P4322 symmetry which is confirmed by the Raman spectroscopy. The paper further analyses the origin of polarization using Maxwell–Wagner fit and Nyquist plot. This work suggests a possible way to increase the relaxor-like ferroelectric ordering, larger span of relaxation temperature (DTm) and the effective masking of electronic contribution by the substitution of Ba2+ ion.
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    Structural, Dielectric, and Magnetic Studies on Electrospun Magnesium Ferrite-Polyvinylidene Fluoride Core–Shell Composite Fibers
    (2014-07-08T06:32:38Z) Revathi, V; Dinesh Kumar, S; Chithra Lekha, P; Subramanian, V; Natarajan, T. S; Muthamizhchelvan, C
    The sub-micron (of the order of 150 nm) thick core–shell composite fibers of magnesium ferrite-polyvinylidene fluoride are prepared by electrospinning. The loading of magnesium ferrite is varied from 1 to 10 wt%. The study results by X-ray diffraction, scanning electron microscope, and infra-red spectroscopy indicate the formation of core–shell structure and an enhancement in the amount of b-phase compared to a-phase in the polyvinylidene fluoride. The particle size of the magnesium ferrite in the fiber is evaluated to be 30 nm. The low frequency dielectric studies indicate that the addition of the magnesium ferrite increases the polarization resulting in the increase in the dielectric constant but decreases the dielectric loss. The magnetization measurements indicate an increased value of coercivity compared to bulk due to the nano-size of the magnesium ferrite. The microwave absorption at the ferromagnetic resonance increases with the increase in the concentration of magnesium ferrite. The resonance field is found to vary with the loading of MFO.
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    Synthesis and Structural studies of Barium Substitute Mangnesium ferrite-polyvinylidene fluoride composite fibers
    (2016-03-01T07:26:54Z) Revathi, V; Subramanian, V; Muthamizhechelvan, C