@article { ISI:000227998900001, title = {Cure characteristics and dielectric properties of magnetic composites containing strontium ferrite}, journal = {Journal of Elastomers and Plastics}, volume = {37}, number = {2}, year = {2005}, month = {APR}, pages = {109-121}, publisher = {SAGE PUBLICATIONS LTD}, type = {Article}, address = {1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND}, abstract = {

Hexagonal strontium ferrite (SrFe12O19) powders were synthesized by the conventional ceramic techniques. They were then characterized by the X-ray diffraction method and incorporated in the natural rubber matrix according to a specific recipe for various loadings of ferrite to produce rubber ferrite composites (RFCs). The processability of these compounds was determined by evaluating the cure characteristics namely, scorch time, cure time, minimum and maximum torque. The evaluation of the dielectric properties of ceramic strontium ferrite (SrF), natural rubber gum vulcanizate, and RFCs were done with the help of a Hewlett Packard (HP) impedance analyzer. The magnetic properties of these composites were studied using a Vibrating Sample Magnetometer (VSM). The effect of carbon black on the processability, and the magnetic and dielectric properties were also studied by the incorporation of carbon black into these composites. It has been found that the addition of these ferrites and carbon black does not affect the processability of these composites, whereas the physical properties are found to be modified. From the magnetic and dielectric measurements it has been found that flexible magnets having appropriate dielectric strength can be prepared by the incorporation of appropriate amount of SrF and carbon black in the natural rubber matrix.

}, keywords = {hexagonal ferrites, Magnetic materials, permanent magnets, rubber ferrite composites (RFCs), strontium ferrite}, issn = {0095-2443}, doi = {10.1177/0095244305046488}, author = {Soloman, M. A. and Kurian, P. and Anantharaman, Maliemadom R. and Joy, Pattayil Alias} } @article { ISI:000230338900005, title = {Low-temperature synthesis of nanocrystalline powders of lithium ferrite by an autocombustion method using citric acid and glycine}, journal = {Materials Letters}, volume = {59}, number = {21}, year = {2005}, month = {SEP}, pages = {2630-2633}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Nanocrystalline lithium ferrite is synthesized by an autocombustion method from the corresponding metal nitrates using citric acid as well as glycine as fuels. The ordered phase of lithium ferrite, in single phase form, with particle size of 32-36 nm and large coercivity, is obtained by this method at a low temperature of 200 degrees C. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Combustion synthesis, LiFe5O8, lithium ferrite, low-temperature synthesis, Magnetic materials, Nanomaterials}, issn = {0167-577X}, doi = {10.1016/j.matlet.2005.04.005}, author = {Verma, S. and Karande, J. and Patidar, A. and Joy, Pattayil Alias} } @article { ISI:000232871700013, title = {Magnetic and processability studies of nitrile rubber vulcanisates containing barium ferrite and carbon black}, journal = {Indian Journal of Chemical Technology}, volume = {12}, number = {5}, year = {2005}, month = {SEP}, pages = {582-587}, publisher = {NATL INST SCIENCE COMMUNICATION}, type = {Article}, address = {DR K S KRISHNAN MARG, NEW DELHI 110 012, INDIA}, abstract = {

Fine particles of barium ferrite (BaFe12O19) belonging to the M-type hexagonal ferrites were prepared by the conventional ceramic techniques. They were incorporated into a nitrile rubber matrix according to a specific recipe for various loadings to produce rubber ferrite composites (RFC)The percolation threshold is not reached for a maximum loading of 130 phr (parts per hundred rubber). Here in this paper, the magnetic properties and processability of the nitrile rubber based RFCs containing barium ferrite (BaF) and HAF carbon black is reported. The magnetic properties of the ceramic ferrite and these rubber ferrite composites were evaluated and it was found that the coercivity values of RFCs were less than that of the ceramic BaF, but remained constant with the loading of both the ferrite filler and carbon black. However, other properties like saturation magnetization and magnetic remanence increased with the loading of ferrite filler.

}, keywords = {barium ferrite, carbon black, Magnetic materials, nitrile rubber, rubber ferrite composites}, issn = {0971-457X}, author = {Soloman, M. A. and Kurian, P. and Anantharaman, Maliemadom R. and Joy, Pattayil Alias} } @article { ISI:000241306000020, title = {Characterization of nanosized NiZn ferrite powders synthesized by an autocombustion method}, journal = {Materials Chemistry and Physics}, volume = {100}, number = {1}, year = {2006}, month = {NOV}, pages = {98-101}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Nanocrystalline Ni0.5Zn0.5Fe2O4 with average particle size of similar to 9 nm has been synthesized by an autocombustion method and characterized by powder XRD, TEM and room temperature magnetic measurements. High room temperature magnetization comparable to that of the bulk material is obtained for the nanosized powders annealed at 800 degrees C, with a maximum particle size of similar to 54 nm. The results show that optimum properties can be achieved for NiZn ferrite powders synthesized by the present autocombustion method and processed at relatively lower temperatures. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Chemical synthesis, Magnetic materials, magnetic properties, Oxides}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.12.012}, author = {Deka, Sasanka and Joy, Pattayil Alias} } @article { ISI:000261361900032, title = {Low temperature synthesis of nanocrystalline lithium ferrite by a modified citrate gel precursor method}, journal = {Materials Research Bulletin}, volume = {43}, number = {12}, year = {2008}, month = {DEC}, pages = {3447-3456}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Single phase nanocrystalline lithium ferrite is synthesized by a modified citrate gel precursor technique. Ferrite nanoparticles of average size of 8 nm, obtained after calcination of the citrate gel Made by the usual method at 450 degrees C, show superparamagnetic behavior. However, small amounts of alpha-Fe(2)O(3) is formed as an impurity phase clue to the initial formation of some gamma-Fe(2)O(3) phase. Oil the other hand, when the pH of the mixed Solution is increased to 7 after the addition of ammonia Solution, a lower calcination temperature of 200 degrees C is sufficient for the formation of single phase lithium ferrite nanoparticles of size 30 nm. No impurity phases are detected when the nanocrystalline powders arc calcined at higher temperatures. The magnetic properties of the ferrite nanoparticles of different sizes obtained by calcining the powders at different temperatures are studied. (C) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {Chemical synthesis, Magnetic materials, magnetic properties, Nanostructures, Oxides}, issn = {0025-5408}, doi = {10.1016/j.materresbull.2008.01.023}, author = {Verma, Seema and Joy, Pattayil Alias} } @article { ISI:000269291500035, title = {Nanocrystalline Mn-Zn-ferrite by novel oxalato-hydrazinated complex method}, journal = {Materials Chemistry and Physics}, volume = {117}, number = {1}, year = {2009}, month = {SEP}, pages = {187-191}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

We report here for the first time the synthesis of technologically important ferrite, using a metal oxalato-hydrazinate (MOH) complex method. The MOH complex of iron-manganese-zinc was synthesized at room temperature using the precursors, ferrous ammonium sulphate, manganese acetate and zinc acetate. Thermo-gravimetric studies of MOH intermediate showed complete phase formation of MnZnFe(2)O(4) at 280 degrees C. XRD data showed the formation of single phase cubic spinel MnZnFe(2)O(4). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate the spherical shape particle morphology. TEM images indicated the particle size of ferrite powder in the range of 20-36 nm. Magnetization of synthesized nano-sized Mn(0.69)Zn(.0.19)Fe(2.12)O(4) was observed coercive force (H(c)) at 127.82 Oe with a saturation magnetization (M(s)), 34.5 emu g(-1) using vibrating sample magnetometer (VSM) at room temperature. Mossbauer study of nano-sized ferrite powder showed super-paramagnteic behavior. (c) 2009 Elsevier B.V. All rights reserved.

}, keywords = {crystal structure, Magnetic materials, Mn-Zn-ferrite, Nanostructures, Optical properties}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2009.05.036}, author = {Kanade, K. G. and Amalnerkar, Dinesh P. and Potdar, H. S. and Kale, B. B.} } @article { ISI:000313404400021, title = {Magnetic properties of nanocrystalline CoFe2O4 synthesized by thermal plasma in large scale}, journal = {Materials Chemistry and Physics}, volume = {137}, number = {2}, year = {2012}, month = {DEC}, pages = {586-595}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The paper reports the large scale synthesis of nanoparticles of CoFe2O4 using thermal plasma reactor by gas phase condensation method. The yield of formation was found to be around 15 g h(-1). The magnetic properties of CoFe2O4, synthesized at different reactor powers, were investigated in view of studying the effect of operating parameters of plasma reactor on the structural reorganization leading to the different cation distribution. The values of saturation magnetization, coercivity and remanent magnetization were found to be influenced by input power in thermal plasma. Although the increase in saturation magnetization was marginal (61 emu g(-1) to 70 emu g(-1)) with increasing plasma power; a significant increase in the coercivity (552 Oe to 849 Oe) and remanent magnetization (16 emu g(-1) to 26 emu g(-1)) were also noticed. The Mossbauer spectra showed mixed spinel structure and canted spin order for the as synthesized nanoparticles. The detailed analysis of cation distribution using the Mossbauer spectroscopy and X-ray photoelectron spectroscopy leads to the conclusion that the sample synthesized at an optimized power shows the different site selective states. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {Magnetic materials, magnetic properties, Mossbauer spectroscopy, Nanostructures}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2012.10.007}, author = {Nawale, A. B. and Kanhe, Nilesh S. and Patil, K. R. and Reddy, V. R. and Gupta, A. and Kale, B. B. and Bhoraskar, S. V. and Mathe, Vikas L. and Das, A. K.} } @article {45747, title = {High magnetostriction parameters of sintered and magnetic field annealed Ga-substituted CoFe2O4}, journal = {Materials Letters}, volume = {192}, year = {2017}, month = {APR }, pages = {169-172}, type = {Article}, abstract = {

Impact of substitution of the non-magnetic ion Ga3+ for Fe3+ on the magnetostriction parameters of CoFe2O4 has been investigated for samples prepared by a tartrate-gel method. All the Ga-substituted compositions in CoGaxFe2-xO4 (0 \<= x \<= 0.3) showed higher strain sensitivity (d lambda/dH), at low magnetic fields, compared to that of the unsubstituted sample. The magnetostriction strain (lambda) and d lambda/dH of the composition CoGa0.1Fe1.9O4 could be enhanced from -228 to -296 ppm and -2.20 x 10(-9) to -3.55 x 10(-9) miA, respectively, at low magnetic fields, after magnetic field annealing at 300 degrees C. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {Cobalt ferrite, Magnetic field annealing, Magnetic materials, Magnetostriction, Substitution}, issn = {0167-577X}, doi = {10.1016/j.matlet.2016.12.031}, author = {Anantharamaiah, P. N. and Joy, P. A.} } @article {43969, title = {Magnetic studies of SiO2 coated CoFe2O4 nanoparticles}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {441}, year = {2017}, month = {NOV}, pages = { 683-690}, type = {Journal Article}, abstract = {Oleic acid capped CoFe2O4 nanoparticles which exhibit a high coercivity of \~{}9.47 kOe at room temperature were coated with a robust coating of SiO2. We have used chemical synthesis method to obtain SiO2 coated CoFe2O4 nanoparticles with different weight percentages of CoFe2O4 in SiO2 (1.5, 3.1 and 4.8 wt.\%). The morphological investigation of the coated nanoparticles by transmission electron microscopy shows that the particles are spherical with average size \~{}160 nm. Infrared spectroscopy reveals that oleic acid capping on the surface of CoFe2O4 nanoparticles is retained after silica coating process. The complete coating of SiO2 on CoFe2O4 nanoparticles is confirmed by X-ray photoelectron spectroscopy as there is no signature of cobalt or iron ions on the surface. Magnetic measurements show that coercivity of SiO2 coated CoFe2O4 particles remains more or less unaffected as in CoFe2O4 nanoparticles at room temperature. In addition, the temperature dependent magnetic measurements show that at 5 K the CoFe2O4 and SiO2 coated 1.5 wt.\% CoFe2O4 samples exhibit a very high value of coercivity (\~{}20 kOe) which is more than twice as compared to room temperature coercivity value (\~{}9.47 kOe). We conclude that silica coating in our study does not significantly affect the coercivity of CoFe2O4 nanoparticles.}, keywords = {Coatings, coercive force, High Resolution Transmission Elctron Microscopy, infrared spectroscopy, Magnetic materials}, doi = { 10.1016/j.jmmm.2017.06.061}, author = {Limaye, M.V.}, editor = {Singh, S.B.} } @article {45491, title = {Large enhancement in the magnetostriction parameters of the composite of CoFe2O4 and CoFe1.9Ga0.1O4}, journal = {Materials Letters}, volume = {236}, year = {2019}, month = {FEB }, pages = {303-306}, type = {Article}, abstract = {

A new strategy to enhance the magnetostriction parameters of cobalt ferrite (CoFe2O4) is illustrated. A composite comprising of nanocrystalline CoFe2O4 and bulk CoFe(1.9)Ga(0.1)O(4 )powders were mixed together then compacted and sintered at 1450 degrees C for 10 min. For a composite of 70 wt\% CoFe2O4 and 30 wt\% of CoFe(1.9)Ga(0.1)O4, maximum magnetostriction coefficient (lambda(max)) of -350 ppm has been obtained at lower magnetic field which is nearly 20\% and 65\% higher than that obtained for CoFe2O4 and CoFe1.9Ga0.1O4, respectively. Moreover, the composite exhibited higher strain sensitivity [d lambda/dH](max )of -2.6 x 10 (9) A(-1) m against the individual components of the composite. (C) 2018 Published by Elsevier B.V.

}, keywords = {Ceramics, Composite materials, Magnetic materials}, issn = {0167-577X}, doi = {10.1016/j.matlet.2018.10.115}, author = {Anantharamaiah, P. N. and Joy, P. A.} } @article {46074, title = {Magnetic parameters of SrFe12O19 sintered from a mixture of nanocrystalline and micron-sized powders}, journal = {Ceramics International}, volume = {45}, year = {2019}, month = {JUL}, pages = {13592-13596}, type = {Article}, abstract = {

Obtaining higher magnetic parameters is essential for high-power sintered strontium ferrite (SrFe12O19) for various applications. A novel approach has been made to improve the magnetic parameters of sintered strontium ferrite by making self-composites from nano and micron-sized powders. Powders with two different weight ratios (50 wt\% nano:50 wt\% micron and 75 wt\% nano:25 wt\% micron) were mixed together, compacted and sintered at 1200 degrees C for 1 h. For a self-composite of 75 wt\% nano and 25 wt\% micron-sized powders, coercivity (H-c) of 3076 Oe has been obtained, larger than the values for the sintered compacts from the component powders. The present study suggests that the magnetic parameters of sintered SrFe12O19 can be improved by making self-composite comprising of nanocrystalline and micron-sized powders.

}, keywords = {Ceramics, Magnetic materials, microstructures, Self-composites, strontium ferrite}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2019.04.023}, author = {Shashanka, H. M. and Anantharamaiah, P. N. and Joy, P. A.} } @article {49052, title = {Unveiling electronic structure and magnetic properties of AFe2O4 (A = Co, Ni, Zn, and Mg): Synergizing experimentation with DFT investigation}, journal = {Solid State Communications}, volume = {382}, year = {2024}, month = {APR }, pages = {115459}, type = {Article}, abstract = {

This study presents the synthesis of nano-crystalline spinel ferrites AFe2O4 (A = Co2+, Ni+2, Zn+2, and Mg+2), through the sol-gel method, yielding crystallite sizes ranging from 12 to 28 nm. The variation in IR and Raman spectra due to M-O-M bonding supports the variation in lattice parameters. The magnetization measurements revealed that CoFe2O4 has a high saturation magnetization of -55 emu/g and coercivity of -1350 Oe, while ZnFe2O4 exhibited saturation magnetization value of -8 emu/g and coercivity of -16 Oe. In addition, the electronic structure calculated using DFT, which corroborated the antiparallel alignment of Fe ions in the tetrahedral and octahedral sites, validating the measured magnetic moments. Notably, the CoFe2O4 ferrite exhibited a higher squareness ratio than other ferrites, signifying its suitability as a magnetic material for audiovideo recording.

}, keywords = {Density functional theory, Ferrites, Magnetic materials, X-ray diffraction}, issn = {0038-1098}, doi = {10.1016/j.ssc.2024.115459}, author = {Dhaka, Saroj and Shukla, Aarti and Garima and Poonia, Kavita and Kumar, Sudesh} }