@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:000236784200028, title = {Finite size effects on the structural and magnetic properties of sol-gel synthesized NiFe2O4 powders}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {302}, number = {1}, year = {2006}, month = {JUL}, pages = {190-195}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Nanoparticles of nickel ferrite have been synthesized by the sol-gel method and the effect of grain size oil its structural and magnetic properties have been Studied in detail. X-ray diffraction (XRD) studies revealed that all the samples are single phasic possessing the inverse spinel structure. Grain size of the sol-gel synthesized powders has been determined from the XRD data and the strain graph. A grain size of 9 nm was observed for the as prepared powders of NiFe2O4 obtained through the sol-gel method. It was also observed that strain was induced during the firing process. Magnetization measurements have been carried out on all the samples prepared in the present series. It was found that the specific magnetization of the nanosized NiFe2O4 powders was lower than that of the corresponding coarse-grained counterparts and decreased with a decrease in grain size. The coercivity of the sol-gel synthesized NiFe2O4 nanoparticles attained a maximum value when the grain size was 15 nm and then decreased as the grain size was increased further. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {grain size, magnetic properties, Nanoparticles, Nickel ferrite, strain}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2005.08.029}, author = {George, M. and John, A. M. and Nair, S. S. and Joy, Pattayil Alias and Anantharaman, Maliemadom R.} } @article { ISI:000244006000001, title = {Direct comparison of the aging and memory effects of magnetic nanoclusters and nanoparticles}, journal = {Solid State Communications}, volume = {141}, number = {6}, year = {2007}, month = {FEB}, pages = {307-310}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The magnetic characteristics of a dense magnetic nanoparticle system and a spin glass system consisting of magnetic nanoclusters are compared. Zero field cooled and field cooled magnetization measurements, including aging and memory experiments, of the nanoparticle and the magnetic cluster systems show similar characteristics, suggesting a common origin for the spin glass-type behavior of the magnetic nanoparticle and nanocluster systems. (C) 2006 Published by Elsevier Ltd.

}, keywords = {Magnetic nanoparticles, magnetic properties, spin glasses}, issn = {0038-1098}, doi = {10.1016/j.ssc.2006.11.015}, author = {Sankar, C. Raj and Vijayanand, S. and Verma, Seema and Joy, Pattayil Alias} } @article { ISI:000246042800003, title = {Synthesis and magnetic properties of Mn doped ZnO nanowires}, journal = {Solid State Communications}, volume = {142}, number = {4}, year = {2007}, month = {APR}, pages = {190-194}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Mn doped ZnO nanowires have been synthesized using a simple autocombustion method. The as-synthesized Mn doped ZnO nanowires were characterized by X-ray diffraction and transmission electron microscopy. An increase in the hexagonal lattice parameters of ZnO is observed on increasing the Mn concentration. Optical absorption studies show an increment in the band gap with increasing Mn content, and also give evidence for the presence of Mn2+ ions in tetrahedral sites. All Zn1-xMnxO (0 \<= x \<= 0.25) samples are paramagnetic at room temperature. However, a large increase in the magnetization is observed below 50 K. This behavior, along with the negative value of the Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicate ferrimagnetic behavior. The origin of ferrimagnetism is likely to be either the intrinsic characteristics of the Mn doped samples, or due to some spinel-type impurity phases present in the samples that could not be detected. (c) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {Combustion synthesis, diluted magnetic semiconductor, magnetic properties, Mn doped ZnO}, issn = {0038-1098}, doi = {10.1016/j.ssc.2007.02.017}, 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:000261061100016, title = {Magnetic and Mossbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method}, journal = {Hyperfine Interactions}, volume = {183}, number = {1-3}, year = {2008}, month = {APR}, pages = {99-107}, publisher = {SPRINGER}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

The properties of nanocrystalline Ni(0.5)Zn(0.5)Fe(2)O(4) synthesized by an auto-combustion method have been investigated by magnetic measurements and Mossbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673-1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Mossbauer spectroscopy. The as-synthesized powder with average particle size of similar to 9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Mossbauer spectroscopic studies.

}, keywords = {Ferrite, magnetic properties, Mossbauer spectroscopy, Nanoparticles}, issn = {0304-3843}, doi = {10.1007/s10751-008-9736-3}, author = {Sreeja, V. and Vijayanand, S. and Deka, Sasanka and Joy, Pattayil Alias} } @article { ISI:000271843400019, title = {Ferromagnetic properties of glucose coated Cu2O nanoparticles}, journal = {Solid State Communications}, volume = {149}, number = {47-48}, year = {2009}, month = {DEC}, pages = {2199-2201}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Magnetic properties of glucose coated cuprous oxide nanoparticles of different sizes have been studied. Unlike bulk Cu2O, which shows diamagnetic behavior, the nanoparticles show superparamagnetic behavior. A superparamagnetic blocking temperature of 21 K is observed for 5 nm particles. A magnetic hysteresis loop with a coercivity of 406 Oe is observed for these particles at 5 K. The magnetization and the coercivity increase with decreasing particle size. The superparamagnetic behavior, along with the increase in magnetization and coercivity with decreasing particle size, is due to the enhanced surface contributions to the magnetism. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Chemical synthesis, Cuprous oxide, magnetic properties, Nanoparticles}, issn = {0038-1098}, doi = {10.1016/j.ssc.2009.09.013}, author = {Mahajan, Mangesh B. and Pavan, M. S. and Joy, Pattayil Alias} } @article { ISI:000207804200008, title = {Single step synthesis and properties of M/MFe2O4 and PVDF/M/MFe2O4 (M = Co, Ni) magnetic nanocomposites}, journal = {Science of Advanced Materials}, volume = {1}, number = {3}, year = {2009}, month = {DEC}, pages = {262-268}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

Metal/ferrite nanocomposites (M/MFe2O4; M = Co, Ni), consisting of nanoparticles of a metal and the corresponding metal ferrite, have been synthesized under in situ conditions by a simple and single step process. The metal/ferrite nanocomposites embedded in a polymer matrix have been prepared by a simple hot-pressing method. The performance parameters such as magnetization, coercivity, permeability and dielectric constant of the two- and three-phase nanocomposite systems are compared. The coercivity increases and the permeability decreases with increasing polymer content in the three-phase composite. Enhancement of the dielectric constant is observed at low frequencies.

}, keywords = {Dielectric, Ferrite, magnetic properties, Nanocomposite, Nanocrystalline, permeability}, issn = {1947-2935}, doi = {10.1166/sam.2009.1053}, author = {Deka, Sasanka and Joy, Pattayil Alias and Kumar, A. Pratheep} } @article { ISI:000276938100029, title = {On the magnetic and dielectric properties of nickel-neoprene nanoconaposites}, journal = {Materials Chemistry and Physics}, volume = {121}, number = {1-2}, year = {2010}, month = {MAY}, pages = {154-160}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Nickel nanocomposites were prepared by incorporating nickel nanoparticles in a neoprene matrix according to a specific recipe for various loadings of nickel particles. The dielectric properties of these composites were evaluated for different frequencies ranging from 100 kHz to 8 MHz at different temperatures from 30 degrees C to 120 degrees C. The dielectric permittivity increases with increase of nickel concentration. Increase in temperature enhances the permittivity initially, till 40 degrees C and thereafter the permittivity decreases. The dielectric loss exhibits relaxation peaks and the peaks shift to lower frequencies with increase in volume fraction of the nickel nanoparticles in the matrix. The evaluation of magnetic and dielectric properties of these composites suggests that the dielectric permittivity can be tailored by an appropriate loading of the filler using semi-empirical equations and the magnetic properties vary according to simple mixture equations. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Composite materials, dielectric properties, Elastomers, magnetic properties}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2010.01.006}, author = {Jamal, E. Muhammad Abdul and Joy, Pattayil Alias and Kurian, Philip and Anantharaman, Maliemadom R.} } @article { ISI:000276615500006, title = {On the magnetic, mechanical and rheological properties of rubber-nickel nanocomposites}, journal = {Polymer Bulletin}, volume = {64}, number = {9}, year = {2010}, month = {MAY}, pages = {907-923}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Rubber-nickel nanocomposites were synthesized by incorporating freshly prepared nanometric nickel particles in two different matrices namely natural rubber and neoprene rubber according to specific recipes for various loadings of nano nickel and the cure characteristics of these composites were evaluated. The maximum torque values register an increase with the increase in loading of nickel in both composites and this is attributed to the non-interacting nature of nickel nanoparticles with rubber matrices. The cure time of natural rubber composites decreases with increase in the content of nickel, and in neoprene rubber cure, time increases with increase in filler content. In natural rubber, the curing reaction seems to be activated by the presence of nickel particles. The magnetization studies of the composites reveal that the magnetic properties of nickel are retained in the composite samples. The elastic modulus of natural rubber and neoprene rubber are largely improved by the incorporation of nickel particles.

}, keywords = {Cure characteristics, Elastic modulus, magnetic properties, Nanocomposites}, issn = {0170-0839}, doi = {10.1007/s00289-009-0231-z}, author = {Jamal, E. Muhammad Abdul and Joy, Pattayil Alias and Kurian, Philip and Anantharaman, Maliemadom R.} } @article { ISI:000300591700013, title = {Effect of inter-particle interactions on the magnetic properties of magnetite nanoparticles after coating with dextran}, journal = {International Journal of Nanotechnology}, volume = {8}, number = {10-12, SI}, year = {2011}, month = {JAN}, pages = {907-915}, publisher = {INDERSCIENCE ENTERPRISES LTD}, address = {WORLD TRADE CENTER BLDG, 29 ROUTE DE PRE-BOIS, CASE POSTALE 896, CH-1215 GENEVA, SWITZERLAND}, abstract = {

Nanoparticles of magnetite (Fe3O4) are synthesised by a coprecipitation method and coated with the biocompatible polymer, dextran. The uncoated and dextran coated magnetite nanoparticles are characterised by powder X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and magnetic measurements. The magnetic properties of the uncoated and coated magnetite nanoparticles are compared to study the effect of inter-particle magnetic interactions on the magnetic characteristics. Absence of magnetic hysteresis at room temperature indicates the superparamagnetic nature of the two samples. Evidence for the effect of reduced inter-particle magnetic interactions is directly obtained from the field dependence of magnetisation at room temperature. The decreased superparamagnetic blocking temperature and the nature and shape of the field cooled magnetisation curve of the dextran coated sample further confirmed that the inter-particle magnetic interactions are completely suppressed after coating.

}, keywords = {dextran coating, magnetic interactions, magnetic properties, magnetite, Nanoparticles}, issn = {1475-7435}, author = {Sreeja, V. and Joy, Pattayil Alias} } @article { ISI:000307039700023, title = {Enhanced magnetic parameters in the morphotropic phase boundary region of nanocrystalline multiferroic Bi1-xLaxFeO3}, journal = {Solid State Communications}, volume = {152}, number = {16}, year = {2012}, month = {AUG}, pages = {1609-1612}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Antiferromagnetic multiferroic BiFeO3 shows ferromagnetic characteristics by simultaneous substitution of Bi by La and decrease in the particle size to nanometer dimensions. Large changes in saturation and remnant magnetization, magnetic susceptibility at low and high fields, along with some anomalous changes in the magnetic transition temperature are observed in nanocrystalline Bi1-xLaxFeO3 system for 0.1 \<= x \<= 0.2. This compositional region corresponds to the morphotropic phase boundary (MPB) region separating the rhombohedral and orthorhombic phases, and the effect is similar to that observed in many ferroelectric systems. The present observation of enhanced ferromagnetic parameters in the MPB region of the nanocrystalline multiferroic La substituted BiFeO3 system, combined with the known ferroelectric characteristics, is suitable for future device applications. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Bismuth ferrite, magnetic properties, Multiferroics, Nanocrystalline materials}, issn = {0038-1098}, doi = {10.1016/j.ssc.2012.05.011}, author = {Thakuria, P. and Joy, Pattayil Alias} } @article { ISI:000324311200017, title = {Influence of initial particle size on the magnetostriction of sintered cobalt ferrite derived from nanocrystalline powders}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {346}, year = {2013}, month = {NOV}, pages = {96-102}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The role of initial particle size on the magnetostriction coefficient of sintered cobalt ferrite derived from nanocrystalline powders is studied. Nanoparticles of cobalt ferrite with different sizes in the range 3-80 nm are synthesized by an autocombustion method using metal nitrates and glycine. It has been observed that the initial particle size of the starting powders has a strong influence on the magnetostrictive behavior of sintered cobalt ferrite. Highest magnetostrictive strain and strain derivative are obtained for sintered ferrite derived from nanoparticles of size \< 5 nm. The results show that higher magnetostriction coefficient for sintered cobalt ferrite can be achieved by compacting nanocrystalline particles of very small size. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Cobalt ferrite, magnetic properties, Magnetostriction, Microstructure, Nanocrystalline, Particle size}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2013.07.016}, author = {Mohaideen, Kamal Khaja and Joy, Pattayil Alias} } @article { ISI:000329479500021, title = {Magnetism in disordered carbon as a function of the extent of graphitization}, journal = {Solid State Communications}, volume = {177}, year = {2014}, month = {JAN}, pages = {89-94}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Magnetic properties of disordered carbon have been investigated as a function of the extent of graphitization. It is found that the magnetization of the disordered carbon decreases with increasing degree of graphitization. Treatment with acid modifies the magnetic characteristics considerably and the original magnetic characteristics are retained upon further heat treatment. The results show that the intrinsic magnetic behavior of the disordered carbon depends on the microstructure and that the edge states play a critical role in deciding the magnetic interactions in the amorphous carbon system. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Amorphous carbon, disordered carbon, Graphitization, magnetic properties}, issn = {0038-1098}, doi = {10.1016/j.ssc.2013.09.037}, author = {Raj, K. Govind and Joy, Pattayil Alias} } @article {46089, title = {Size-controlled cobalt ferrite nanocrystals: magnetically separable reusable nanocatalysts for selective oxidation of styrene}, journal = {ChemistrySelect}, volume = {4}, year = {2019}, month = {JUN }, pages = {6524-6531}, type = {Article}, abstract = {

Superparamagnetic cobalt ferrite (CFO) nanocrystals (NCs) with sizes similar to 6 nm and similar to 4 nm were synthesized using a facile solvothermal method using fatty acids, lauric acid and stearic acid, as the capping agents. The synthesized nanocrystals were well characterized by XRD, FT-IR, XPS, SEM and TEM. The formation mechanism was explored and it was shown that the fatty acid was actually chemisorbed as a carboxylate onto the surface of CFO NCs. The experimental results specify that the size and size distribution of the CFO NCs were highly dependent on the length of fatty acid hydrophobic chain. Corresponding changes of the magnetic properties were investigated by measuring magnetization as a function of field and temperature, which suggest that the CFO NCs were superparamagnetic in nature. The catalytic properties for the oxidation of styrene in organic medium were examined by using the synthesized CFO NCs with sizes similar to 6 nm and similar to 4 nm. The synthesized CFO NCs, well dispersible in organic media, were demonstrated to be highly catalytically active, reached 100\% conversion of styrene in 12 h with similar to 77\% and similar to 82\% selectivity for styrene oxide respectively. The magnetic CFO nanocatalysts were easily separated and recovered from the reaction medium by an external magnet, and reused for several cycles without losing catalytic selectivity for styrene oxide.

}, keywords = {Cobalt ferrite, epoxidation, Fatty acids, magnetic properties, nanocrystals}, issn = {2365-6549}, doi = {10.1002/slct.201900714}, author = {Jeyavani, Vijayakrishnan and Pawar, Sayali and Dadwal, Arun and Joy, Pattayil Alias and Mukherjee, Shatabdi Porel} }