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.

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.

Synthesis, Microstructure and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite by a Modified Wet Chemical Method

2008 ◽  
Vol 368-372 ◽  
pp. 594-597
Author(s):  
Yin Liu ◽  
Tai Qiu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Wet Chemical Method ◽  
Specific Saturation Magnetization ◽  
Random Anisotropy ◽  
Zn Ferrite ◽  
Wet Chemical ◽  
Critical Grain Size ◽  
Microstructure And Magnetic Properties

Nanocrystalline Ni1-xZnxFe2O4 ferrites with 0 ≤ x ≤ 1 were prepared by sprayingcoprecipitation method. The microstructure was investigated by TG-DSC, XRD, SEM, TEM and BET. Magnetic properties were measured with vibrating sample magnetometer at room temperature. The results showed that uniform and fine nanocrystalline Ni1-xZnxFe2O4 ferrites are obtained. The grain size of sample calcined at 600°C for 1.5h is about 30nm. There are a few agglomerates with average sizes below 100nm. The specific saturation magnetization, Ms, of the sample increases with increasing Zn2+ concent x at room temperature, and the maximum Ms is 66.8 A·m2·kg-1 as the Zn2+ content x is around 0.5mol. As calcining temperature increased from 400°C to 1050°C, the Ms of Ni0.5Zn0.5Fe2O4 ferrite increases from 40.2 A·m2·kg-1 to 75.6 A·m2·kg-1. The coercivity maximum is about 5.97 kA·m-1 as its critical grain size is about 62.0nm. The relation between coercivity and grain size for nanocrystalline Ni0.5Zn0.5Fe2O4 ferrite may be explained based on random anisotropy theory.

Effect of grain size on the activation energy for plastic deformation near room temperature in a Zn–28.7 pct Al–1.9 pct Cu alloy

2007 ◽  
Vol 42 (17) ◽  
pp. 7617-7620 ◽  
Author(s):  
J. D. Muñoz-Andrade ◽  
A. Mendoza-Allende ◽  
E. Cabrera ◽  
G. Torres-Villaseñor ◽  
J. A. Montemayor-Aldrete
Keyword(s):  
Activation Energy ◽  
Plastic Deformation ◽  
Grain Size ◽  
Room Temperature ◽  
Cu Alloy

Preparation, Structural and Electrical Properties of Nanocrystalline Zr-Mn Cobalt-Ferrite Synthesized by the Co-Precipitation Method

2012 ◽  
Vol 510-511 ◽  
pp. 248-254
Author(s):  
K. Khan
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Frequency Band ◽  
Electrical Characterization ◽  
Drift Mobility ◽  
Precipitation Method ◽  
Dc Electrical Resistivity ◽  
Ft Ir ◽  
Ir Study ◽  
Co Precipitation

The present study describes the preparation, structural and electrical characterization of nanosized Zr-Mn cobalt-ferrites. The nominal compositions CoFe2-2xZrxMnxO4 (0.10.4) have been synthesized by the co-precipitation method. These nanopowder products were sintered in furnace at temperature of 800 °C for 8 hour with a heating rate of 10οC/min to obtain these ferrites. The nanopowder was evaluated using XRD, FT-IR and SEM. The XRD data showed that all the samples are of single phase and the crystallite size is found in the range of 2630 nm. The lattice constant (a), X-ray density (dx), porosity (P) and bulk density (dm) are also calculated from XRD data. FT-IR study confirms the presence of ferrite functional groups. The IR spectra of Zr-Mn ferrite system have been analyzed in the frequency range 400650 cm-1. It revealed two prominent bands υ1 and υ2 which are assigned to tetrahedral and octahedral metal complexes, respectively. The position of the highest frequency band is around 550 cm-1 while the lower frequency band is around 425 cm-1. The structural properties are also analyzed on scanning electron microscopy (SEM) at room temperature. Additionally, the dc electrical resistivity decreased with the rise in temperature for all the samples, showing a semiconductor like behavior. From the dc electrical resistivity the activation energy and drift mobility are determined. Both the drift mobility and activation energy increase with a rise in x.

Density and Mechanical Strength of Ferrite for Inertial Gyroscope

2007 ◽  
Vol 546-549 ◽  
pp. 2265-2268
Author(s):  
Zhong Yu ◽  
Zhong Wen Lan ◽  
Ke Sun ◽  
Yu Chen
Keyword(s):  
Grain Size ◽  
Fracture Surface ◽  
Crystal Lattice ◽  
Lattice Constant ◽  
Bending Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zn Ferrite ◽  
Electronic Microscope ◽  
Crystal Lattice Constant

The effects of NiO on density and mechanic strength of Mn-Zn ferrite used for inertial gyroscope were investigated by measurements of crystal lattice constant, Vickers hardness, bending strength. To investigate this further, powder of Mn-Zn ferrite was characterized by x-ray diffraction (XRD) and the fracture surface of Mn-Zn ferrite was checked by scanning electronic microscope (SEM). The investigation revealed that the substitution of Ni2+ modified crystal lattice constant and crystal grain size so that it caused crystal lattice constant of Mn-Zn ferrite to decline and crystal grain size to decrease, therefore it was useful to improve density and mechanic strength of Mn-Zn ferrite by this way. The results show that proper addition of NiO can bring higher density and more perfect mechanic strength of Mn-Zn ferrite used for inertial gyroscope.

scholarly journals Electrical Resistivity, Thermoelectric Power and I-V Characteristics of Sb-Se Thin Films at Different Compositions.

2020 ◽  
Vol 9 (7) ◽  
pp. 894-896
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Electrical Resistivity ◽  
Thermoelectric Power ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Selenium Concentration ◽  
Negative Temperature ◽  
Glass Substrates ◽  
Exponential Change

Sb-Se thin films of varying composition have been deposited on glass substrates at room temperature. These films were annealed at temperature interval of 50 0K. The electrical resistivity (ρ) and thermoelectric power (α) of same films were measured. The resistance of semiconducting films decreases rapidly on heating showing negative temperature coefficient of resistance (T.C.R.). The composition dependent resistivity shows exponential change, sharp fall of resistivity may be attributed due to increase of metallic ‘Sb’ in Sb-Se thin films. The composition dependent activation energy of Sb-Se thin films has been calculated. The activation energy (∆E) of semiconducting films was found to increase with selenium concentration. For different compositions thermoelectric power (α) increases upto 70 at. wt.% of Se concentration and then slowly decreases. The I-V characteristics of Sb-Se thin films were measured using copper (Cu) contacts. The films show ohmic conduction for different applied voltages as well as various concentrations of Selenium (Se) in Sb-Se thin films

High Strength FeCo–V Intermetallic Alloy: Electrical and Magnetic Properties

2005 ◽  
Vol 20 (6) ◽  
pp. 1515-1522 ◽  
Author(s):  
R.S. Sundar ◽  
S.C. Deevi ◽  
B.V. Reddy
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Electrical Resistivity ◽  
Room Temperature ◽  
Age Hardening ◽  
High Coercivity ◽  
Aged Alloy ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Hardening Behavior

Age-hardening behavior of a new generation of FeCo alloys [Fe–40Co–5V–0.005B–0.015C–0.5Mo–0.5Nb (at.%)] is characterized by microhardness, tensile testing, electrical resistivity, and magnetic properties. The alloy exhibits maximum hardening when aged at 600 °C. Precipitation of γ2 (V-rich face-centered cubic phase) during aging appears to be responsible for the observed hardening behavior. The alloy exhibits superior creep resistance when subjected to solutionizing in γ phase field and aged at 600 °C. On the other hand, the room temperature tensile ductility of the aged alloy depends on the grain size, which in turn can be controlled by varying the solutionizing condition. The age-hardened alloy exhibits a room temperature electrical resistivity of 70–75 μΩ cm. The higher resistivity of the present alloy as opposed to the commercial FeCo–2V alloys is attributed to the high V content of the alloy. Structure-sensitive magnetic properties like coercivity and core losses of the alloy are affected by the aging treatment, and the maximum coercivity is observed when the alloy is aged at 600 °C. High coercivity of the alloy is attributed to the fine distribution of paramagnetic γ2 precipitate, fine grain size, and internal stress arising from phase transformation.

Influence of Sn4+ on Structural and DC Electrical Resistivity of Ni-Zn Ferrite Thick Films

2016 ◽  
Vol 46 (3) ◽  
pp. 1427-1438 ◽  
Author(s):  
S. P. Dalawai ◽  
T. J. Shinde ◽  
A. B. Gadkari ◽  
N. L. Tarwal ◽  
J. H. Jang ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Thick Films ◽  
Dc Electrical Resistivity ◽  
Zn Ferrite

SYNTHESIS AND ELECTRICAL RESISTIVITY OF NICKEL POLYMETHACRYLATE

1992 ◽  
Vol 06 (10) ◽  
pp. 581-586 ◽  
Author(s):  
M. H. CHOHAN ◽  
A. H. KHALID ◽  
M. ZULFIQAR ◽  
P. K. BUTT ◽  
FARAH KHAN ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Sodium Hydroxide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Polymethacrylic Acid

Synthesis of nickel polymethacrylate was carried out using methanolic solutions of sodium hydroxide and polymethacrylic acid. The electrical resistivity of the pellets made from Ni-polymethacrylate was measured at different voltages and temperatures. Results showed that the electrical resistivity of Ni-polymethacrylate decreases significantly with voltage in high temperature regions but the decrease is insignificant at temperatures nearing room temperature. The activation energy at low temperatures is approximately 0.8 eV whereas at high temperature it is in the range 0.21–0.27 eV.

Electrical, Dielectrical and Magnetic Properties of Zr-Mn Doped Nano-Ferrites

2012 ◽  
Vol 510-511 ◽  
pp. 301-306
Author(s):  
K. Khan ◽  
Ashari Maqsood
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Drift Mobility ◽  
Nominal Composition ◽  
Frequency Range ◽  
Energy Increase ◽  
Dielectric Parameters ◽  
Dc Electrical Resistivity ◽  
Low Field ◽  
Mn Doped

We measured the dc electrical resistivity as a function of temperature and dielectric parameters in the frequency range 100 Hz to 3 MHz of nanosized Zr-Mn spinel ferrites with nominal composition CoFe2-2xZrxMnxO4(0.1x0.4). The dc electrical resistivity decreased with the rise in temperature for all the samples, showing a semiconductor like behavior. From the dc electrical resistivity the activation energy and drift mobility are determined. Both the drift mobility and activation energy increase with a rise inx. The dielectric constant, dielectric (losses) and ac electrical resistivity as a function of frequency are also reported. The low field ac magnetic susceptibility measurement showed that the ferrimagentic transition temperature is in the range of 4395 K to 6585 K.

Sign in / Sign up

Export Citation Format

Share Document