Effect of Chromium Substitution on the Structural, Magnetic and Electrical Properties of Nano Crystalline Co0.6Zn0.4Cu0.2CrxFe1.8-xO4 Ferrite

2013 ◽  
Vol 202 ◽  
pp. 173-192 ◽  
Author(s):  
Sonal Singhal ◽  
Santosh Bhukal
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Characteristics ◽  
Copper Ferrite ◽  
Vibrating Sample Magnetometer ◽  
Dc Electrical Resistivity ◽  
X Ray ◽  
Nano Crystalline ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Chromium Substitution

Nano-crystalline Co0.6Zn0.4Cu0.2CrxFe1.8-xO4 (x = 0.2, 0.4, 0.6 and 0.8), have been synthesized using a citrate sol-gel auto combustion method and annealed at different temperature 400 °C, 600 °C, 800 °C and 1000 °C. The effect of chromium substitution on the structural, magnetic and dielectric properties of cobalt-zinc-copper ferrite has been studied. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and Vibrating Sample Magnetometer (VSM) techniques. The X-ray diffractogram of all the annealed samples confirm the formation of single phase with Fd-3m space group. The crystalline sizes have been found to increase (from ~15 nm – to 60 nm) with the annealing temperature. The DC electrical resistivity of all the ferrites has been measured using a two-probe method between temperature range of 30 °C to 100 °C. The DC electrical resistivity of all the samples decrease with increase in temperature indicates semiconducting nature. However, the DC resistivity increase as the Cr3+ concentration increases because the Cr3+ ions enter the octahedral sites and reduce the electron exchange between Fe2+ and Fe3+ causing a decrease in polaron hopping of Fe2+-Fe3+ions. The value of the Seebeck coefficient (S) for all the ferrites is found to be positive indicating that all the ferrite samples behave as p-type semiconductors. The effect of copper chromium cation distribution among the tetrahedral (A) and octahedral (B) sites of Co-Zn substituted ferrite on magnetization and coercivity field have been investigated using VSM (vibrating sample magnetometer) technique. The decrease in the saturation magnetization (Ms) with increasing chromium content may be attributed to the copper and chromium enters into the octahedral site of the Co-Zn ferrite.

Study of the magnetic and structural properties of Al–Cr codoped Y-type hexaferrite prepared via sol–gel auto-combustion method

2015 ◽  
Vol 29 (14) ◽  
pp. 1550090 ◽  
Author(s):  
O. Mirzaee ◽  
R. Mohamady ◽  
A. Ghasemi ◽  
Y. Alizad Farzin
Keyword(s):  
Magnetic Properties ◽  
Sol Gel ◽  
Combustion Method ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Shape ◽  
Auto Combustion ◽  
Xrd Patterns ◽  
Cr Doping

Nanostructure of Y-type hexaferrite with composition of Sr 2 Ni 2 Al x/2 Cr x/2 Fe 12-x O 22 (where x are 0, 0.6, 1.2, 1.8, 2.4 and 3) were prepared by sol–gel auto-combustion method. The influence of Al and Cr doping on the structural and magnetic properties has been investigated. The X-ray diffraction (XRD) patterns confirm phase formation of Y-type hexaferrite. The microstructure and morphology of prepared samples were studied by high resolution field emission scanning electron microscope (FESEM) which shows the hexagonal shape for all of the samples. Magnetic properties were characterized using vibrating sample magnetometer (VSM). The magnetic results revealed that by increasing the Al and Cr to the structure, the coercivity was also increased from 840 Oe to 1160 Oe. Moreover it has been shown that with addition of dopants, saturation magnetization (Ms) and remnant magnetization (Mr) were decreased from 39.61 emu/g to 30.11 emu/g and from 17.51 emu/g to 14.62 emu/g, respectively, due to the entrance of nonmagnetic ions into Fe 3+ sites.

Structure, Magnetic Properties and Defects Distribution of Mn0.5Zn0.5LaxFe2-xO4 Nanocrystals

2010 ◽  
Vol 105-106 ◽  
pp. 706-708
Author(s):  
Li Qun Wang
Keyword(s):  
Sol Gel ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Zn Ferrite ◽  
Mean Grain Size ◽  
Sol Gel Process ◽  
La Substitution ◽  
The Mean

La-substitution Mn-Zn ferrite nanocrystals, Mn0.5Zn0.5LaxFe2-xO4 (x=0.00, 0.05, 0.10, 0.15, 0.20) were prepared by sol-gel process. X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and positron annihilation lifetime spectroscopy (PALS) studies were carried out. The result of XRD suggests that the mean grain size decreases from 63.8 nm to 44.6 nm with the increment of La-substitution concentration from x=0.00 to 0.20. The VSM measurement shows that the saturation magnetization (MS) increases in the range of x<0.10, then it drastically decreases in the range of 0.10<x<0.20. At last, defects property is discussed using PALS.

Study of electrical and magnetic properties of Ni–Zn–Mg ferrite system

2014 ◽  
Vol 28 (31) ◽  
pp. 1450244 ◽  
Author(s):  
B. Rajesh Babu ◽  
B. B. V. S. Vara Prasad ◽  
M. S. R. Prasad
Keyword(s):  
Electrical Resistivity ◽  
Initial Permeability ◽  
Magnesium Concentration ◽  
X Ray Diffraction ◽  
Polycrystalline Nickel ◽  
Dc Electrical Resistivity ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Air Atmosphere

Polycrystalline nickel–zinc ferrites of chemical formula Ni 0.65-x Mg x Zn 0.35 Fe 2 O 4 (x = 0.00 to 0.2 in steps of 0.04) have been prepared by conventional ceramic technique. Calcination and sintering of all samples have been carried out in air atmosphere at 950°C and 1250°C, respectively, followed by natural cooling to room temperature. All the samples were characterized by the X-ray diffraction (XRD) for structure determination. These samples were then investigated for their magnetic and electric properties, including saturation magnetization, Curie temperature, initial permeability measurements and DC electrical resistivity. Porosity was decreased drastically from 15% to 5% showed better quality of the sintered samples. There were increments in initial permeability and DC electrical resistivity throughout the series of samples. Variations in the observed properties as a function of magnesium concentration have been discussed in light of the existing understanding.

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.

scholarly journals Effect of Al3+ Substitution On Magnetic and DC Electrical Resistivity Properties of NiZnCu Nanoferrites

2021 ◽  
Author(s):  
N MURALI
Keyword(s):  
Electrical Resistivity ◽  
Negative Temperature Coefficient ◽  
Sol Gel ◽  
Combustion Process ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion ◽  
Ft Ir ◽  
Resultant Material

Abstract Al substituted Ni0.4Zn0.35Cu0.25Fe2-xAlxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) samples is synthesized using the sol-gel auto-combustion process. X-ray diffraction shows its cubic spinel structure. The lattice constant decreases as the Al3+ content increases. The sizes of the crystallites are also decreasing in the range of 32.15 nm to 22.89 nm. The wavenumbers of tetrahedral and octahedral sites sighted in the FT-IR spectra are similar to that of the precursor. The increment in the Al3+ content increases the DC conductivity. The electrical resistivity decrease with an increase in the temperature, i.e., it has a negative temperature coefficient with resistance similar to semiconductors. VSM results show their isotropic nature forming single domain ferrimagnetic particles. The resultant material is widely significant, as indicated by its result.

SOFT MAGNETIC PROPERTIES OF Mg0.7-xNi0.3ZnxFe2O4 FERRITES SYNTHESIZED BY SOL-GEL AUTO-COMBUSTION TECHNIQUE WITHOUT POST-PREPARATION THERMAL TREATMENT

2013 ◽  
Vol 22 ◽  
pp. 28-34 ◽  
Author(s):  
A. GHOSH ◽  
M. SATALKAR ◽  
S. RATHOD ◽  
S. P. NAG ◽  
P. VYAS ◽  
...  
Keyword(s):  
Large Scale ◽  
Single Phase ◽  
Spinel Ferrite ◽  
Sol Gel ◽  
Soft Magnetic ◽  
X Ray ◽  
Nano Crystalline ◽  
Auto Combustion ◽  
Zn Content ◽  
Combustion Technique

Single phase nanocrystalline soft magnetic Mg 0.7-x Ni 0.3 Zn x Fe 2 O 4, ferrites with x = 0.0 − 0.7 were prepared by sol gel auto-combustion method. X-ray diffraction confirms the formation of single phase nano-crystalline cubic spinel ferrites with average grain diameter ranging between 12.9 nm to 23.9 nm. Formation of the ferrite phase without subsequent heat treatment makes sol-gel auto combustion technique especially suitable and economical for the large scale industrial production of the nano-crystalline ferrites for multilayer chip inductor applications (MLCI). Both, lattice parameter and X-ray density shows a linear increase with increasing Zn 2+ concentration, attributed to the difference in ionic radii and density of Mg and Zn . Increase in Zn content enhances the soft magnetic behavior, exhibiting linear decrease of coercivity from 122.34 Oe to 72.45 Oe, explained by increase of density with Zn addition. The maximum magnetization (Mmax)increases up to 0.106 Tesla (for x = 0.4) and. then decreases with increase of Zn content, discussed on the basis of increase of the occupancy of A-site in spinel ferrite by non-magnetic Zn 2+ ion.

Correlation of Microstructures with Electrical Transport Properties in Mn Doped Co Nanoferrite Particles

2012 ◽  
Vol 510-511 ◽  
pp. 487-492
Author(s):  
M. Akram ◽  
M. Anis-ur-Rehman ◽  
S. Nasir ◽  
G. Asghar
Keyword(s):  
Electrical Resistivity ◽  
Transport Properties ◽  
Cation Distribution ◽  
Electrical Transport ◽  
Research Work ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Dc Electrical Resistivity ◽  
X Ray

Magnetic nanocomposites are offering a variety of novel features and tune able properties, mainly depending on particle size, cation distribution, morphology and porosity of the prepared materials. The aim of this research work is to understand the effects of Mn doping on the microstructures and hence consequences on the electrical transport properties with shift of cation distribution in CoFe2O4. Co1-xMnxFe2O4nanocrystallite particles with stoichiometric proportion (x) varying from 0.0 to 1.0 were prepared by co-precipitation method. X-ray diffraction patterns confirmed the FCC spinel structure of synthesized particles. The crystal structure is found to be inverse cubic spinel with a space group Fd3m and the lattice constants ranges from 8.36 Å to 8.46 Å The crystallite sizes were calculated from the most intense peak (311) using the Debye-Scherrer formula for all the samples those were synthesized at reaction temperature of 70°C. Then samples were sintered at 600°C for 3 hours, characterized by X-ray diffraction at room temperature and DC electrical resistivity measurements were done as a function of temperature by two-probe method from 370 K to 690 K. The measurements showed that DC electrical resistivity decreased with increase in temperature ensuring the semiconductor nature of the material in this temperature range. DC electrical resistivity results were discussed in terms of polaron hopping model under the effects of cation distribution. AC electrical properties were also analyzed. All the observed properties were correlated with observed microstructures.

Magnetic, structural and dc electrical resistivity studies on the divalent cobalt substituted Ni–Zn ferrite system

2015 ◽  
Vol 29 (12) ◽  
pp. 1550067 ◽  
Author(s):  
M. Siva Ram Prasad ◽  
B. B. V. S. V. Prasad ◽  
B. Rajesh Babu
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Electrical Resistivity ◽  
Lattice Constant ◽  
Room Temperature ◽  
Error Function ◽  
Positive Contribution ◽  
Dc Electrical Resistivity ◽  
Cobalt Substitution ◽  
Zn Ferrite

Polycrystalline cobalt substituted Ni – Zn ferrite with composition Ni 0.65-x Co x Zn 0.35 Fe 2 O 4(x = 0.00–0.25 insteps of 0.05) have been prepared through the conventional solid state ceramic method. Calcination and sintering have been performed in air atmosphere at 950°C and 1250°C for 4 h and 2 h, respectively followed by natural cooling to room temperature. X-ray diffraction patterns of all samples indicated the formation of the single spinel structure and the accurate lattice parameter for each composition has been determined using the Nelson–Riley error function. The increase in lattice constant on cobalt substitution is attributed to the ionic radius difference between the displaced and the substituted ion. The variation in lattice constant on incorporation of Co 2+ ion indicates its solubility into the spinel lattice and noticeable modification in structural properties have been observed. The observed increase in the saturation magnetization and Curie temperature with the increase in the Co 2+ substitution is due to its higher magnetic moment compared to that of Ni 2+, improvement in the A–B exchange interaction mechanism and large positive contribution to magnetic anisotropy due to presence of Co 2+ when they are at the octahedral sites. The observed variation in the initial magnetic permeability and the magnetic loss factor with cobalt substitution measured at a low frequency of 1 KHz have been attributed to the modification in the density, porosity, grain size and anisotropy contributions. A nearly comparable variation is observed in the room temperature dc electrical resistivity and activation energy for conduction and is attributed to the modification in structure, role and nature of cobalt ions and the microstructure aspects like grain size and pore concentration. The activation energy values in the range of 0.28 to 0.36 eV suggest a possible electron hopping. The observed changes in the structural and the magnetic and electrical properties have all been discussed in the light of exiting understanding.

Sign in / Sign up

Export Citation Format

Share Document