Structural, electrical and magnetic studies of nickel–zinc nanoferrites prepared by simplified sol–gel and co-precipitation methods

Spinel mixed Li-ferrites with incorporation of various dopants (Cd 2+ and Ni 2+ ) concentration in ranges 0.00 ≤ x ≤ 0.80 are prepared using sol-gel technique. The various phases, lattice constant/parameter, X-ray density and crystallite size are confirmed using X-ray diffraction (XRD). The particle size and lattice parameters are found in the range 15-33 nm and 8.35-8.66 Å. This confirmed that incorporating dopant strongly influences the material structure and an increase is observed in lattice parameter and particle size with increase in dopant concentration. The structure is influenced by the dopant position, at the octahedral (B) and tetrahedral (A) sites. The decrease in activation energy (E) is observed with increase in dopant concentration. Furthermore, analysis of the crystallite size and morphology is done using scanning electron microscopy (SEM), which confirmed that the observed particle size is comparable with the X-ray diffraction (XRD) results. The dopant affects electrical properties such as dc electrical resistivity and drift mobility. The observed trend for drift mobility and dc electrical resistivity confirmed the semiconducting behavior of the synthesized material. The magnetic parameters saturation magnetization (M s ), remanence (M r ) and coercivity (H c ) are strongly affected by dopant concentration. A sudden increase in magnetic parameters M r and M s is observed A. Faraz ( ) Thermal Transport Laboratory (TTL), School of chemical and materials Engineering (by incorporating a small amount of dopant up to x = 0.40 and with further incorporation cause a decrease in the values of these parameters due to the non-magnetic behavior of incorporating dopant Cd 2+ ions. These decreases in values can be explained using the spin canted model and cations positioning at tetrahedral (A) and octahedral (B) sites. The decrease in Curie temperature, observed with increase in dopant incorporation, is due to the decrease/weakening interaction between tetrahedral (A) and octahedral (B) sites.

Section: X-rays and Sem Analysismentioning

confidence: 99%

Effect of Dopants Mn2+ and Cd2+ Concentration on Electrical and Magnetic Properties of Li-Mixed Spinel Nanoferrites

Faraz

Ahmad

2011

“…All the peaks of as-prepared and sintered samples matched with the mentioned reference cards. The analysis showed that samples have a cubic spinel ferrite structure [10,11]. The width of XRD peaks of the sintered sample has reduced and the peaks have become more visible due to the release of stresses, strains and dislocations from the crystal structure of the sample [12].…”

Section: Structural Analysismentioning

confidence: 99%

“…The lattice constant has remained almost the same but the crystallite size has reduced as shown in Table 1. With the help of the following formula (1) and (2) the theoretical (ρ thy ) and experimental (ρ exp ) densities were determined [10,14] …”

Section: Structural Analysismentioning

confidence: 99%

Electrical Properties of Ni-Zn Ferrite Nanoparticles Prepared by Simplified Sol-Gel Method

Munir

Ahmed

Saqib

et al. 2014

Ferrites have become the source of attention for scientists due to their variety of physical properties. Their massive use in the electronics industry has made the study of their dielectric, thermal, and optical properties unavoidable. These materials have potential applications in high-frequency devices. The empirical formula for the synthesized nanoparticles is given by Ni 0.5 Zn 0.5 Fe 2 O 4 . Nanoferrites were prepared by a simplified sol-gel method. The crystalline phase; crystallite size; surface morphology; dielectric properties such as AC conductivity (σ AC ), dielectric constant ( ), and dielectric loss (tanδ) as a function of frequency at different temperatures; and DC electrical resistivity as a function of temperature were studied. The Ni-Zn nanoferrite was sintered at 550 • C. The X-ray diffraction (XRD) results showed a spinel cubic structure having a lattice constant a = 8.383Å and crystallite size of 12 nm for the (311) peak after sintering. Scanning electron microscopy showed the particle morphology of the samples. AC conductivity (σ AC ) increases with frequency as well as the temperature. DC resistivity decreased with increase in temperature. The observed behavior could be explained by the Maxwell-Wagner model. Parameters observed were correlated to understand the conduction mechanism.

“…The particle size is observed in the range 17-36 nm; and the values are listed in Table 1. From XRD data various physical parameters such as X-ray density (ρ x ), measured density (ρ m ), and cell volume (V ) are calculated using standard relations [8].…”

Section: Structural Spectroscopic and Morphological Studiesmentioning

confidence: 99%

Effect of Mn2+ and Cd2+ on the Physical Properties of Li-Mixed Spinel Nanoferrites

Faraz

Maqsood

2011

The mixed Li-ferrites with dopants Mn 2+ and Cd 2+ are synthesized by chemical co-precipitation method. Structural and morphology analysis with X-ray diffraction (XRD) and SEM, respectively, confirmed the spinel structure with uniform distribution of the nanoparticles of the size in the range 17-36 nm. The dopant concentration affects the lattice parameter by incorporating Cd 2+ , lattice parameter increases in the range 8.3-8.7 Å. This increase is attributed due to difference in ionic radii of cations. The dc electrical resistivity (ρ dc ) and drift mobility (μ d ) confirmed a semiconducting-like behavior. The increase in dopant concentration decreases the activation energy ( E). A small amount of Cd 2+ causes a sudden increase in saturation magnetization (M s ) and remanence (M r ) values. It is observed that up to x = 0.30 M s increases, while further incorporation of Cd 2+ decreases magnetization. This is due to canted spin and can be explained on the basis of the canted spin model. The decrease in Curie temperature with increase in Cd 2+ is due to interaction between tetrahedral (A) and octahedral (B) lattice sites.