Ibetombi Soibam

Synthesis And Characterization Of Ultra‐fine Zinc Substituted Lithium Ferrites

Ultrafine substituted lithium ferrite having the compositional formula Li0.5‐0.5xZnxFe2.5‐0.5xO4 where 0⩽x⩽1.0 in steps of 0.2 were prepared by the citrate Precursor method. A nitrate citrate gel was prepared from metal nitrates and citric acid, which exhibits self‐propagating combustion behaviour. Spinel structure of the synthesized ferrite was confirmed by XRD analysis. The variation in lattice parameter and density with zinc concentration is studied.

A correlated structural and electrical study of manganese ferrite nanoparticles with variation in sintering temperature

Manganese ferrite nanoparticles were prepared by chemical co-precipitation method. Metal chlorides and sodium hydroxide were used as precursor. The spinel phase formation of the prepared samples was confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). From the XRD data, the average crystallite size and lattice constant were calculated. FTIR spectra reveal the characteristic absorption bands of spinel ferrite due to M-O stretching vibrations in tetrahedral and octahedral sites. Manganese ferrite nanoparticles were further given sintering. The effect of sintering at different temperatures on the structural properties such as XRD, FTIR and electrical properties such as dielectric constant, dielectric loss and ac-conductivity was studied. Possible mechanism of structural changes and observed electrical behavior due to sintering is being discussed. A strong correlation has also been observed in the results obtained from different characterization techniques.

Structural and Initial Permeability Studies of Li-Zn-Co Ferrites

A series of cobalt substituted lithium zinc ferrites having the compositional formula Li0.4–0.5xZn0.2CoxFe2.4–0.5xO4, where 0.00 ≤ x ≤ 0.1 in steps of 0.02, was prepared by the citrate precursor method. Structural studies on the prepared samples were carried out by using XRD and SEM measurements. Spinel phase structure of the samples was confirmed by XRD. From the XRD data the lattice parameter and the theoretical density were calculated. The experimental density was also determined using the Archimedes principle. Lattice parameter was observed to increase with increasing Co2+ ion concentration. The densification in both the cases, theoretical and experimental, shows an increase with composition. SEM studies carried out show that average grain diameter are in the range of 300 nm–650 nm and a fall is observed with increasing Co2+ ion content. The investigation on initial permeability as a function of composition and frequency were also undertaken. It is seen that there is decrease in the value of initial permeability with addition of Co content. The initial permeability and permeability loss show dispersion with frequency. Possible mechanisms contributing to the above processes are discussed.

Synthesis and Photoluminescence Studies of Ni Substituted ZnO Nanoparticles

Nickel (Ni) substituted ZnO nanopowders were synthesized by simple and efficient co-precipitation method with zinc nitrate and nickel nitrate as the starting materials. Effect of Ni substitution on structural and photoluminescence properties of ZnO nanopowders has been studied. Structural characterization of the as prepared powders was performed with X-ray diffraction (XRD) studies. It was confirmed that all the powders were of zinc oxide having polycrystalline nature and possessing typical hexagonal wurtzite structure. Both lattice parameters a and c decreases from 3.257 to 3.214 A and 5.217 to 5.156 A, respectively with increase in Ni content from 0 to 10 wt % while the crystallite size calculated from the XRD data decreases from 29.8 to 14.2 nm, respectively. The effect of Ni substitution on the photoluminescent properties of ZnO nanopowders was also studied in order to exploit their possible application in nanoscale optoelectronic devices. The synthesized ZnO nanopowder samples showed a broad UV photoluminescence (PL) emission peak at 3.14 eV.

STRUCTURAL, ELECTRICAL AND MAGNETIC STUDIES OF Li–Zn–Ni FERRITES

Ni substituted Li–Zn ferrites with compositional formulas Li0.4-0.5xZn0.2NixFe2.4-0.5xO4, where x = 0.02 ≤ x ≤ 0.1 in steps of 0.02, is synthesized by a chemical method using citrate precursors. The prepared ferrites are investigated for their structural, electrical and magnetic properties. Ni substitution significantly changes the characteristic properties of Li–Zn ferrites. There is an increase in grain growth as determined from SEM measurements. An increase in the room temperature DC resistivity is observed with the addition of Ni. The room temperature initial permeability shows an overall decrease with Ni concentration, which is explained with respect to saturation magnetization and supplemented by nuclear hyperfine field obtained from Mossbauer analysis. The variation of the complex permeability with frequency is measured over the frequency range of 100 Hz–1 MHz and dispersion is found. A possible mechanism contributing to the above process is discussed.