Abdul Gaffoor; D. Ravinder; V. Nathanial
Abstract
Nano crystalline cobalt substituted lithium ferrites having chemical formula [Li 0.5Fe0.5]1-x Cox Fe2O4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been prepared by the citrate gel auto combustion method at low temperature (180 o C). The prepared samples were sintered at 500 o C for 4 hours. Single ...
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Nano crystalline cobalt substituted lithium ferrites having chemical formula [Li 0.5Fe0.5]1-x Cox Fe2O4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been prepared by the citrate gel auto combustion method at low temperature (180 o C). The prepared samples were sintered at 500 o C for 4 hours. Single phase of these samples were confirmed by x-ray powder diffraction technique and found that lattice parameter increases with increasing with the Cobalt substituted concentration, and the values of crystallite size, x-ray density, bulk density and porosity of the prepared samples were calculated from the XRD analysis. The dc electrical resistivities of the prepared Li-Co ferrites were studied by using the two probe method in the temperature range of 473-873 K (200-600 o C). A plot of log (?T) vs inverse of temperature yields a almost straight line which reveals the semiconducting behavior of prepared ferrite samples. The dielectric properties namely dielectric constant (ε'), dielectric loss tangent (tan δ) of these Li-Co nano crystalline ferrites have been studied using an LCR meter from the room temperature to 700 K at various selected frequencies up to 5 MHz. The dielectric constant (ε') of all prepared samples was increased with increasing in temperature. These results have been explained on the basis of Koop’s theory, concentration of Fe +2 and Fe +3 ions on the octahedral site and hoping frequency of charge carriers (electrons) between Fe +2 and Fe +3 ions.
Sandeep Kumar; L. K. Sahay; Anal K. Jha; K. Prasad
Abstract
A low-cost, green and reproducible stearic acid assisted synthesis of nanocrystalline powder of (Ag0.5Fe0.5)TiO3 (n-AFT) is reported. X-ray, FTIR, energy dispersive X-ray and transmission electron microscopy analyses are performed to ascertain the formation of n-AFT. Rietveld refinement of X-ray data ...
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A low-cost, green and reproducible stearic acid assisted synthesis of nanocrystalline powder of (Ag0.5Fe0.5)TiO3 (n-AFT) is reported. X-ray, FTIR, energy dispersive X-ray and transmission electron microscopy analyses are performed to ascertain the formation of n-AFT. Rietveld refinement of X-ray data indicated the formation of a single-phase monoclinic structure. Individual nanoparticles almost spherical in shape having the sizes of 5-14 nm are found. The mechanism of nanotransformation for the soft-chemical synthesis of n-AFT has been explained using nucleation and growth theory. UV-visible study revealed the surface plasmon resonance at 318 nm. Dielectric study revealed a low value of dielectric constant (= 177) and dielectric loss (= 0.013) at 1 kHz. Magnetic studies have been carried out using vibration sample magnetometer, which indicated the possibility of magnetoelectric coupling.
