scholarly journals Magnetic and electrical properties of Cr substituted Ni nano ferrites

2018 ◽  
Vol 12 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Kumar Vijaya ◽  
Rapolu Sridhar ◽  
Dachepalli Ravinder
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Average Crystallite Size ◽  
Soft Magnetic Materials ◽  
Ion Concentration ◽  
Dc Resistivity ◽  
Soft Magnetic ◽  
Loop Area ◽  
Auto Combustion ◽  
Resistivity Variation

Nano-ferrites with composition NiCrxFe2-xO4 (where x = 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were synthesized through citrate-gel auto combustion technique at moderately low temperature. X-ray analysis shows cubic spinel structure single phase without any impurity peak and average crystallite size in the range 8.5-10.5 nm. Magnetic properties were measured using a vibrating sample magnetometer at room temperature in the applied field of ?6 KOe. The obtained M-H loop area is very narrow, hence the synthesized nano ferrites are soft magnetic materials with small coercivity. Magnetic parameters such as saturation magnetization (Ms), coercivity (Hc), remanent magnetization (Mr) and residual magnetization were measured and discussed with regard to Cr3+ ion concentration. Electrical properties were measured using two probe method from room temperature to well beyond transition temperature. The DC resistivity variation with temperature shows the semiconductor nature. Resistivity, drift mobility and activation energy values are measured and discussed with regard to composition. The Curie temperature was determined using DC resistivity data and Loria-Sinha method. The observed results can be explained in detail on the basis of composition.

scholarly journals Influence of Annealing Temperature on the Crystallization Kinetics of Fe82Si8B10 Amorphous Ribbon

2020 ◽  
Vol 11 (1) ◽  
pp. 107-112
Author(s):  
A Said Sikder ◽  
SD Nath ◽  
SS Sikder
Keyword(s):  
Crystallization Kinetics ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Amorphous Ribbon ◽  
Primary Crystallization ◽  
Soft Magnetic Materials ◽  
Power Transformers ◽  
Soft Magnetic ◽  
Potential Applications ◽  
Kinetics Of

Amorphous soft magnetic materials have significant potential applications in specialist power transformers and in inductive devices. With the composition of Fe82Si8B10, 82% of the transition metals Fe and about 18% of metalloid or glass-former elements like B and Si are strongly magnetic at room temperature and offer dynamic opportunities for engineering applications. The crystallization kinetics has been studied by differential thermal analysis (DTA). The sample was annealed in a controlled way in the temperature range of 350-450°C at constant annealing time one hour. The kinetics of primary crystallization α-Fe(Si) phase and secondary crystallization Fe2B phase was studied as affected due to temperature. The sample annealed at 350oC temperature is almost unchanged which is still lower than that of primary crystallization temperature but the same condition when sample annealed at 450°C completely shows that the primary crystallization α-Fe(Si) phase has vanished and crystallization event took place to a good extent. Journal of Engineering Science 11(1), 2020, 107-112

scholarly journals Structural phase transformations during deformation Of Fe-Co-V alloys using the high-pressure torsion method

2021 ◽  
pp. 16-23
Author(s):  
L. F. Muradimova ◽  
◽  
A. M. Glezer ◽  
S. O. Shirshikov ◽  
I. V. Shchetinin ◽  
...  
Keyword(s):  
High Pressure ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Structural Phase ◽  
Soft Magnetic Materials ◽  
Magnetic Characteristics ◽  
Structural Parameter ◽  
Soft Magnetic ◽  
Co Alloys

Fe-Co alloys belong to the soft magnetic materials and have an extremely high value of saturation magnetization σ at room temperature. In particular, Fe-Co alloy with the equiatomic ratio of components at room temperature has the maximal σ value among all known ferromagnetic materials. Unfortunately, it is hard to reproduce the unique magnetic properties of these alloys (especially Fe-Co alloys) due to their high fragility caused mainly by the formation of far atomic ordering according to B2 type in the structure. Adding vanadium to the Fe-Co alloys increases plasticity, but it reduces basic magnetic characteristics. In this paper, using the X-ray structural analysis, transmission scanning microscopy, and magnetometry, the authors analyzed the influence of high-pressure torsion at the temperatures of 77 and 295 K on the structure and phase composition of soft magnetic alloys (Fe-Co)100-xVx (x=0–6.0). As the principal structural parameter before and after deformation, the authors analyzed the magnitude of γ-phase volume ratio in the BCC magnetic matrix. The study identified that plastic deformation causes the suppression of formation of excessive γ-phase in alloys containing (3.0–6.0) % V. The study shows that the loss of γ-phase is observed with the increase of high-pressure torsion deformation firstly in the alloys with the high vanadium proportion and at the deformation effect at higher temperature (295 K). The authors conclude that the detected effect is a consequence of γ→α martensite transformation caused by deformation by analogy to TRIP-effect. The study identified that the suppression of paramagnetic γ-phase leads to a noticeable increase in the specific saturation magnetization.

scholarly journals Investigation of Structural, Magnetic and Electrical Properties of Chromium Substituted Nickel Ceramic Nanopowders

2021 ◽  
Author(s):  
Rapolu Sridhar ◽  
D. Ravinder ◽  
J. Laxman Naik ◽  
K. Vijaya Kumar ◽  
N. Maramu ◽  
...  
Keyword(s):  
Structural Information ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Ion Concentration ◽  
Structural Parameter ◽  
Dielectric Parameters ◽  
Auto Combustion ◽  
Ray Density ◽  
Cr Doping

Nano-ceramic of NiCrxFe2-xO4 (0.1 ≤ x ≤ 1.0) ferrites were synthesized by citrate-gel auto combustion method. The structural parameter such as lattice parameter, X-ray density, bulk density and porosity variations with Cr doping were studied. The average crystallite size is in the range 8.5–10.5 nm. The surface morphology and elemental analysis was studied with SEM (EDAX) spectrum and the structural information analyzed with FTIR spectra. Magnetic properties were discussed with Cr3+ion concentration. Electrical parameters like dc resistivity and drift mobility were reported with function of temperature and dopent concentration from room temperature to well beyond Curie temperature and explained with hopping mechanism between Fe2+↔Fe3+ ions. The activation energies in ferri and para magnetic regions were investigated. Dielectric parameters like dielectric constant, dielectric loss and ac conductivity were investigated variation with frequency and composition.

Processing of FeCo Nanosized Soft-Magnetic Material by Powder Metallurgy Technique

2007 ◽  
Vol 558-559 ◽  
pp. 707-715 ◽  
Author(s):  
W.M. Daoush
Keyword(s):  
Electrical Properties ◽  
Sintered Material ◽  
Hydrogen Atmosphere ◽  
Soft Magnetic Materials ◽  
Sodium Hypophosphite ◽  
Metallic State ◽  
Soft Magnetic ◽  
Prepared Powder ◽  
Saturation Induction ◽  
Magneto Resistance

A nanosized cobalt-based alloy containing 20 wt % Fe was synthesis by electroless chemical reduction method using alkaline tartarate bath and sodium hypophosphite as a reducing agent . The powder was investigated by optical microscope, SEM and XRD to identify the powder shape, size and the chemical composition. The prepared powder has a spherical shape with a particle size of about 200 nm. The investigated powder was cold compacted at 600 MPa and then sintered in hydrogen atmosphere at 1050 0C. Metallographic, physical, magnetic and electrical properties investigations were carried out for the prepared powder and its sintered compacts. The prepared powder has 2.5% phosphorus content which was liberated by heating the compacts to the sintering temperature in hydrogen atmosphere. From the results of the density measurements we can observe that the prepared sintered FeCo material had a relative density about 96% to the theoretical. But the results of the electrical properties measurements give an indication of the decreasing in the electrical resistivity than the materials produced by the traditional methods. On the other hand the magnetic measurements, of the FeCo powder has a lower specific saturation induction, Bs, than the sintered one which was due to the presence of the paramagnetic metal phosphides in the powder but after rising the temperature to sintering the, Bs, values is increased due to the conversion of the phosphides to the metallic state and the phosphorus was liberated, but the coercive force was decreased by sintering of the powder compacts by lowering the porosity of the materials with sintering and the formation of the soft magnetic materials Fe-Co solid solution which was investigated by XRD having the highest specific saturation induction value. Also the magnetic permeability of the prepared sintered material was increase with increasing the applied field until 50 Oe which has the highest value and decreased with increasing the field more than 50Oe. From the magneto-resistance measurements, it was shown that the sintered material has a positive magneto-resistance in the field direction but a negative one in the direction perpendicular to the current and the field.

scholarly journals Electrical Properties of Li-based NASICON Structured Ceramic Electrolytes Substituted With Chromium

2019 ◽  
Vol 7 (4.14) ◽  
pp. 555
Author(s):  
N. A. Mustaffa ◽  
N. S. Mohamed ◽  
. .
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Room Temperature ◽  
Electronic Conductivity ◽  
Ionic Mobility ◽  
Electrical Impedance Spectroscopy ◽  
Ion Concentration ◽  
Boundary Conductivity ◽  
Ceramic Electrolytes ◽  
Ion Conducting

Electrical properties of Li - ion conducting Li1+xCrxSn2-x(PO4)3 ceramic electrolytes with 0 < x < 1 were studied using electrical impedance spectroscopy in the frequency range of 1 Hz to 10 MHz at room temperature. Impedance analysis showed an increase in bulk and grain boundary conductivity with the increment of x up to x = 0.7. The highest bulk and grain boundary conductivity were 6.52 ×10-6 S cm-1 and 1.62 ×10-6 S cm-1 in the system of Li1.7Cr0.7Sn1.3(PO4)3 at room temperature. The charge carrier concentration,   mobile ion concentration, ionic hopping rate and ionic mobility were calculated by fitting the AC conductivity spectra. The ionic hopping rate and ionic mobility of the compound increased with the substitution of chromium due to the extra interstitial Li+ ions in the system.  Additionally, the highest conducting sample with x = 0.7 had a negligible electronic conductivity based on transference number measurements. These results imply that the Li1+xCrxSn2-x(PO4)3 electrolytes obtained in this work can be considered as future candidates for solid state electrolytes.  

Evolution of Magnetism in CaO-SiO2-P2O5-Na2O-Fe2O3 Bioglass Ceramics

2008 ◽  
Vol 587-588 ◽  
pp. 171-174
Author(s):  
Rajendra Kumar Singh ◽  
A. Perumal ◽  
Govind P. Kothiyal ◽  
A. Srinivasan
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Structural Investigation ◽  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Soft Magnetic Materials ◽  
Soft Magnetic ◽  
Melt Quenching ◽  
Heat Treated ◽  
Magnetite Phase

We report the evolution of magnetism in bioglass ceramics 41CaO.(52-x)SiO2.4P2O5. xFe2O3.3Na2O (2 ≤ x ≤ 10 mole % Fe2O3) prepared by melt quenching technique followed by heat treatment at 1050 oC. The structural investigation revealed the presence of magnetite phase in the heat treated samples with x ≥ 2 mole % Fe2O3. Room temperature magnetic measurements showed a very weak ferrimagnetic behaviour for the sample with x = 2 mole % of Fe2O3. Samples with x > 2 mole % of Fe2O3 exhibited magnetic behavior similar to soft magnetic materials with low coercivity. The evolution of magnetic properties in these samples as a function of Fe2O3 molar concentration is correlated with the amount of magnetite phase present in them.

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