Study of microstructure and augmentation of DC electrical resistivity due to Al3+ substitution in Ni–Zn nano ferrite system synthesized via auto combustion

2015 ◽  
Vol 29 (26) ◽  
pp. 1550151 ◽  
Author(s):  
B. Rajesh Babu ◽  
K. V. Ramesh ◽  
M. Sivaram Prasad ◽  
Y. Purushotham
Keyword(s):  
Electrical Resistivity ◽  
Spinel Phase ◽  
Spinel Ferrite ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Dc Electrical Resistivity ◽  
High Electrical Resistivity ◽  
Air Atmosphere ◽  
Auto Combustion ◽  
Increasing Temperature

Nanocrystalline Ni–Zn–Al spinel ferrite was synthesized via citrate-gel auto combustion method. The as-prepared powders have been separated into two batches in which one batch of powders were sintered at 1000[Formula: see text]C for 4 h and the other batch were pressed into pellets and were sintered at the same temperature. Sintering of the samples was done in air atmosphere followed by natural cooling to room temperature. The heat treated powders have then been characterized using TG–DTA, XRD, SEM and TEM for thermal, structural and microstructural aspects while the DC electrical resistivity measurements were carried out on the sintered pellets. The X-ray diffraction patterns displayed the formation of the spinel phase for all powders and the lattice parameter was obtained using Bragg’s law. The crystallite size for all compositions were found to be in nano dimensions and obtained from the Williamson–Hall method. TG–DTA analysis of the undoped [Formula: see text] indicated the formation of the spinel phase is around 400[Formula: see text]C while almost uniform microstructure with a more or less spherical grains has been noticed in the SEM micrograph. An enhancement in the DC electrical resistivity ([Formula: see text]-cm) has been observed in [Formula: see text] synthesized using this technique in comparison with that processed through conventional ceramic technique and a modification in the resistivity has been observed on substituting [Formula: see text] in place of [Formula: see text]. High electrical resistivity makes these ferrites suitable for high-frequency applications due to possible reduction of the eddy current losses. The observed variation in resistivity has been discussed on amendments in structure, microstructure and unavailability of [Formula: see text] ions with increasing [Formula: see text] ions in the light of existing understanding. The decrease in resistivity with increasing temperature confirms the semiconducting behavior of all samples. Activation energies for conduction were obtained from the slope of the log [Formula: see text] versus [Formula: see text] plots and observed to be in the range of 0.6–0.45 eV. The variation in the activation energy for conduction followed a similar trend as the DC resistivity. The drift mobility decreases with increasing [Formula: see text] ions concentration and increases with increasing temperature.

Structural, dielectric and impedance spectroscopic studies of Ni0.5Zn0.5−xLixFe2O4 nanocrystalline ferrites

2017 ◽  
Vol 31 (22) ◽  
pp. 1750153 ◽  
Author(s):  
Davuluri Venkatesh ◽  
K. V. Ramesh
Keyword(s):  
Ac Conductivity ◽  
Lithium Concentration ◽  
Combustion Method ◽  
Spectroscopic Studies ◽  
Lattice Parameter ◽  
Ion Concentration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Air Atmosphere ◽  
Auto Combustion

Nanocrystalline lithium substituted Ni–Zn ferrites with composition Ni[Formula: see text]Zn[Formula: see text]Li[Formula: see text]Fe2O4 ([Formula: see text] = 0.00–0.25 in steps of 0.05) were synthesized by the citrate gel auto-combustion method and were sintered at 1000[Formula: see text]C for 4 h in air atmosphere. The structural, dielectric, impedance spectroscopic and magnetic properties were studied by using X-ray diffraction, impedance analyzer and vibrating sample magnetometer respectively. The X-ray diffraction patterns confirm that all samples exhibit a single phase cubic spinel structure. Suitable cation distribution for all compositions has been proposed by using the X-ray diffraction line intensity calculations and the theoretical lattice parameter for each composition was observed in close agreement with the experimental ones and thereby supporting the proposed distribution. An increase in the saturation magnetization was observed up to [Formula: see text] = 0.10 level of Li[Formula: see text] substitution and thereafter magnetization reduced for higher concentrations to the highest level of Li[Formula: see text] substitution. The dielectric constant and the DC resistivity of Ni–Zn–Li ferrites were noticed to decrease with increase in the Li[Formula: see text] ion concentration. The impedance spectroscopic studies by using the Cole–Cole plots were studied in order to obtain the relaxation time, grain resistance and grain capacitance. AC conductivity initially remained almost independent of frequency for lower frequencies and thereafter for higher frequencies the AC conductivity increased with increase of Lithium concentration.

Albumen-assisted Synthesis of Nanocrystalline Nickel Ferrite Photocatalyst

2021 ◽  
Vol 14 (5) ◽  
pp. 437-444
Keyword(s):  
Magnetic Properties ◽  
Green Synthesis ◽  
Spinel Ferrite ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Egg White ◽  
Hysteresis Curve ◽  
Blue Dye ◽  
Auto Combustion ◽  
Simple Step

Abstract: As a simple step to remove the polluting dyes in aqua ecosystem, NiFe2O4 nanoparticles well known for their ferromagnetic properties, low conductivity and high electrochemical stability were prepared by simple auto combustion method using egg white as fuel via green synthesis route. The structural, morphological and magnetic properties of prepared NiFe2O4 was analyzed. The desirable phase purity of the prepared spinel ferrite was deliberated by X-ray Diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive and Vibrating Sample Magnetometer (VSM). XRD predicts the phase formation, particle size and lattice parameter of the spinel ferrite. The FTIR spectrum confirms the ferrite structure. The morphological and elemental analysis was made using SEM and EDAX. The hysteresis curve reveals the magnetic properties, such as remanence magnetization (Mr), coercivity (Hc) and saturation magnetization (Ms). The photocatalytic efficiency of the synthesized samples was determined from degradation of methylene blue dye. The whole process was monitored using spectrophotometer at regular intervals of time. The maximum photocatalytic degradation efficiency for NiFe2O4 is around 95.6 %. Keywords: NiFe2O4, Ferrite, Green synthesis, Egg white, Combustion, Photocatalyst.

scholarly journals Structural and Magnetic Property of Cr3+ Substituted Cobalt Ferrite Nanomaterials Prepared by the Sol-Gel Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2095 ◽  
Author(s):  
Jinpei Lin ◽  
Jiaqi Zhang ◽  
Hao Sun ◽  
Qing Lin ◽  
Zeping Guo ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Cobalt Chromium ◽  
X Ray Diffraction ◽  
Chromium Doping ◽  
Auto Combustion ◽  
Cr Concentration

Cobalt-chromium ferrite, CoCrxFe2−xO4 (x = 0–1.2), has been synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD) indicates that samples calcined at 800 °C for 3 h were a single-cubic phase. The lattice parameter decreased with increasing Cr concentration. Scanning electron microscopy (SEM) confirmed that the sample powders were nanoparticles. It was confirmed from the room temperature Mössbauer spectra that transition from the ferrimagnetic state to the superparamagnetic state occurred with the doping of chromium. Both the saturation magnetization and the coercivity decreased with the chromium doping. With a higher annealing temperature, the saturation magnetization increased and the coercivity increased initially and then decreased for CoCr0.2Fe1.8O4.

Structural and magnetic properties of Cr doped strontium spinel ferrite SrFe2O4 by sol-gel auto-combustion method

2018 ◽  
Vol 550 ◽  
pp. 90-95 ◽  
Author(s):  
Nazia Yasmin ◽  
Iqra Inam ◽  
Iftikhar Ahmed Malik ◽  
Maria Zahid ◽  
Muhammad Naeem Ashiq ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Sol Gel ◽  
Combustion Method ◽  
Auto Combustion ◽  
Structural And Magnetic Properties

scholarly journals The influence of the chelating/combustion agents on the structure and magnetic properties of zinc ferrite

2012 ◽  
Vol 10 (6) ◽  
pp. 1799-1807 ◽  
Author(s):  
Tamara Slatineanu ◽  
Eliano Diana ◽  
Valentin Nica ◽  
Victor Oancea ◽  
Ovidiu Caltun ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Zinc Ferrite ◽  
Structural Parameters ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Combustion Method ◽  
Structural Features ◽  
Lattice Parameter ◽  
Zn Ferrite ◽  
Auto Combustion

AbstractThe present study is reporting the influence of the chelating/combustion agents on the magnetic properties of Zn ferrite. Six chelating/combustion agents, citric acid, egg white, tartaric acid, glycine, glucose and urea, were used to obtain monophase zinc nanoferrite via a sol-gel auto-combustion method. The samples were subjected to a comparative study of structural features and magnetic properties by means of infrared spectroscopy, X-ray diffractometry, scanning electron microscopy and vibrating sample magnetometry. Significant influence of fuel and combustion mode was observed in the magnetic behavior of as-obtained samples. Values of the structural parameters were discovered to vary as a function of fuel choice, and to obtain crystallite size between 38 and 62 nm, inversion degree between 0.239 and 0.807, lattice parameter between 8.4125 and 8.4432 Å. The optimization of sol-gel method synthesis of zinc ferrite nanoparticles by chosing the appropriate fuel is providing structural and magnetic properties of zinc nanoferrite as potential materials to be used in biomedical applications.

scholarly journals Structural, Optical, and Catalytic Properties of MgCr2O4 Spinel-Type Nanostructures Synthesized by Sol–Gel Auto-Combustion Method

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1476
Author(s):  
Vasyl Mykhailovych ◽  
Andrii Kanak ◽  
Ştefana Cojocaru ◽  
Elena-Daniela Chitoiu-Arsene ◽  
Mircea Nicolae Palamaru ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Catalytic Properties ◽  
Spinel Phase ◽  
Sol Gel ◽  
Combustion Method ◽  
Temperature Treatment ◽  
X Ray Diffraction ◽  
Spinel Type ◽  
X Ray ◽  
Auto Combustion

Spinel chromite nanoparticles are prospective candidates for a variety of applications from catalysis to depollution. In this work, we used a sol–gel auto-combustion method to synthesize spinel-type MgCr2O4 nanoparticles by using fructose (FS), tartaric acid (TA), and hexamethylenetetramine (HMTA) as chelating/fuel agents. The optimal temperature treatment for the formation of impurity-free MgCr2O4 nanostructures was found to range from 500 to 750 °C. Fourier transform infrared (FTIR) spectroscopy was used to determine the lattice vibrations of the corresponding chemical bonds from octahedral and tetrahedral positions, and the optical band gap was calculated from UV–VIS spectrophotometry. The stabilization of the spinel phase was proved by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis. From field-emission scanning electron microscopy (FE-SEM), we found that the size of the constituent particles ranged from 10 to 40 nm. The catalytic activity of the as-prepared MgCr2O4 nanocrystals synthesized by using tartaric acid as a chelating/fuel agent was tested on the decomposition of hydrogen peroxide. In particular, we found that the nature of the chelating/fuel agent as well as the energy released during the auto-combustion played an important role on the structural, optical, and catalytic properties of MgCr2O4 nanoparticles obtained by this synthetic route.

scholarly journals Effect of Cu Substitution on Magnetic Properties of Co0.6Ni0.4Fe2O4 Nanoferrites

2021 ◽  
Vol 12 (2) ◽  
pp. 1899-1906
Keyword(s):  
Grain Size ◽  
Spinel Structure ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Fesem Image ◽  
Absorption Bands ◽  
Cu Substitution ◽  
Ferrite Structure ◽  
Auto Combustion

This work is focusing on synthesizing the cobalt nanoferrite materials substituted by copper forming Co0.6Ni0.4-xCuxFe2O4 with x = 0.0, 0.1, and 0.3 using the sol-gel auto-combustion method. The phase analysis of XRD showed the spinel structure with the lattice parameter in the range 8.36-8.39 Å. FESEM image showed the grain size initially decreasing and then increasing with Cu concentration. The FTIR curve's two absorption bands in the specified range of frequency assured the spinel nano ferrite structure. The values of remanent ratios obtained from VSM showed their isotropic nature forming single domain ferrimagnetic particles.

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