01755nas a2200217 4500008004100000022001400041245013100055210006900186260007100255300001400326490000600340520092800346653001901274653002101293653002001314653001901334653001401353100002801367700002501395856011701420 2012 eng d a1944-824400aEnhancement in the magnetostriction of sintered cobalt ferrite by making self-composites from nanocrystalline and bulk powders0 aEnhancement in the magnetostriction of sintered cobalt ferrite b a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC a6421-64250 v43 a

Sintered polycrystalline cobalt ferrite is a potential magnetostrictive smart material for applications as sensors and actuators. A novel concept of enhancing the magnetostrictive strain of sintered cobalt ferrite by making self-composites from nanosized and bulk powders with different particle sizes of the same material as components is reported. The self-composites give higher magnetostriction coefficient and strain derivative when compared to the sintered products obtained from the individual powders. The individual components give a maximum magnetostriction up to similar to 310 ppm, whereas up to similar to 370 ppm is obtained for a two-component system consisting of powders of two different sizes. On the other hand, a three-component self-composite made from starting powders of 3 nm, 40 nm and >1 mu m give very high magnetostriction of similar to 400 ppm at 800 kA/m, suitable for making devices.

10aCobalt ferrite10aMagnetostriction10aNanocrystalline10aself-composite10aSintering1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/enhancement-magnetostriction-sintered-cobalt-ferrite-making-self-composites-001798nas a2200217 4500008004100000022001400041245014400055210006900199260007300268300001400341490000700355520092600362653001901288653002901307653002101336653002001357653002001377100002801397700002501425856013001450 2013 eng d a1567-173900aHigh magnetostriction coefficient of Mn substituted cobalt ferrite sintered from nanocrystalline powders and after magnetic field annealing0 aHigh magnetostriction coefficient of Mn substituted cobalt ferri aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcOCT a1697-17010 v133 a

Magnetostriction characteristics of Mn substituted cobalt ferrite, CoFe2-xMnxO4 (0 <= x <= 0.3), sintered from nanocrystalline powders of average particle size of similar to 4 nm have been studied. Larger value of magnetostriction at lower magnetic field is achieved after substitution of Mn for Fe. The maximum value of magnetostriction coefficient is not much affected and the slope of the magnetostriction is increased with increasing Mn content. Higher maximum value of magnetostriction coefficient (lambda) of 234 ppm comparable to that of the unsubstituted composition with larger strain derivative (d lambda/dH) is obtained for x = 0.2 in CoFe2-xMnxO4. The magnetostriction coefficient is increased to 262 ppm with further enhancement in the strain derivative after annealing the sintered compact at 300 degrees C in a magnetic field of 400 kA/m for 30 min. (C) 2013 Elsevier B.V. All rights reserved.

10aCobalt ferrite10aMagnetic field annealing10aMagnetostriction10aMn substitution10aNanocrystalline1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/high-magnetostriction-coefficient-mn-substituted-cobalt-ferrite-sintered-nanocrystalline-001678nas a2200229 4500008004100000022001400041245012700055210006900182260007300251300001100324490000800335520080900343653001901152653002401171653002101195653001901216653002001235653001801255100002801273700002501301856012201326 2013 eng d a0304-885300aInfluence of initial particle size on the magnetostriction of sintered cobalt ferrite derived from nanocrystalline powders0 aInfluence of initial particle size on the magnetostriction of si aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV a96-1020 v3463 a

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.

10aCobalt ferrite10amagnetic properties10aMagnetostriction10aMicrostructure10aNanocrystalline10aParticle size1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/influence-initial-particle-size-magnetostriction-sintered-cobalt-ferrite-derived-001776nas a2200193 4500008004100000022001400041245011300055210006900168260007300237300001200310490000800322520100800330653001901338653002101357653002401378100002801402700002501430856012701455 2014 eng d a0304-885300aHigh magnetostriction parameters for low-temperature sintered cobalt ferrite obtained by two-stage sintering0 aHigh magnetostriction parameters for lowtemperature sintered cob aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC a121-1290 v3713 a

From the studies on the magnetostriction characteristics of two-stage sintered polycrystalline CoFe2O4 made from nanocrystalline powders, it is found that two-stage sintering at low temperatures is very effective for enhancing the density and for attaining higher magnetostriction coefficient. Magnetostriction coefficient and strain derivative are further enhanced by magnetic field annealing and relatively larger enhancement in the magnetostriction parameters is obtained for the samples sintered at lower temperatures, after magnetic annealing, despite the fact that samples sintered at higher temperatures show larger magnetostriction coefficients before annealing. A high magnetostriction coefficient of similar to 380 ppm is obtained after field annealing for the sample sintered at 1100 degrees C, below a magnetic field of 400 kA/m, which is the highest value so far reported at low magnetic fields for sintered polycrystalline cobalt ferrite. (C) 2014 Elsevier B.V. All rights reserved.

10aCobalt ferrite10aMagnetostriction10aTwo-stage sintering1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/high-magnetostriction-parameters-low-temperature-sintered-cobalt-ferrite-obtained-two-002009nas a2200217 4500008004100000022001400041245014500055210006900200260009900269300001200368490000700380520113300387653001901520653002101539653001901560653002001579653001401599100002801613700002501641856012501666 2014 eng d a0955-221900aStudies on the effect of sintering conditions on the magnetostriction characteristics of cobalt ferrite derived from nanocrystalline powders0 aStudies on the effect of sintering conditions on the magnetostri aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAR a677-6860 v343 a

The effect of sintering conditions on the magnetostriction characteristics of sintered cobalt ferrite derived from nanocrystalline powders is studied. It is observed that the magnetostriction coefficient as well as the slope of the magnetostriction as a function of field depends on the microstructure of the sintered product. There is a direct correlation between the magnetostriction characteristics and density as well as porosity of the sintered products. Intragranular pores are found to be strongly influencing the magnetostriction characteristics. Similarly, correlation is found between the magnetostriction parameters and the Curie temperature, indicating the role of cation distribution which affects the magnetic anisotropy. Sintering the compacts made from nanocrystalline powders at 1450 degrees C for a very short duration is found to give high values of magnetostriction coefficient. However, higher values of magnetostriction at low magnetic fields are obtained for samples sintered at lower temperatures for longer duration and having relatively lower density. (C) 2013 Elsevier Ltd. All rights reserved.

10aCobalt ferrite10aMagnetostriction10aMicrostructure10aNanocrystalline10aSintering1 aMohaideen, Kamal, Khaja1 aJoy, Pattayil, Alias uhttps://library.ncl.res.in/content/studies-effect-sintering-conditions-magnetostriction-characteristics-cobalt-ferrite-001434nas a2200217 4500008004100000022001400041245010000055210006900155260000900224300001200233490000800245520067900253653001900932653002900951653002300980653002101003653001701024100002701041700001601068856013201084 2017 eng d a0167-577X00aHigh magnetostriction parameters of sintered and magnetic field annealed Ga-substituted CoFe2O40 aHigh magnetostriction parameters of sintered and magnetic field  cAPR  a169-1720 v1923 a

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.

10aCobalt ferrite10aMagnetic field annealing10aMagnetic materials10aMagnetostriction10aSubstitution1 aAnantharamaiah, P., N.1 aJoy, P., A. uhttps://library.ncl.res.in/content/high-magnetostriction-parameters-sintered-and-magnetic-field-annealed-ga-substituted-cofe2o402310nas a2200253 4500008004100000022001400041245013000055210006900185260000900254300001400263490000600277520143200283653001901715653001601734653001601750653002401766653001701790100002901807700001801836700001701854700002501871700003101896856012901927 2019 eng d a2365-654900aSize-controlled cobalt ferrite nanocrystals: magnetically separable reusable nanocatalysts for selective oxidation of styrene0 aSizecontrolled cobalt ferrite nanocrystals magnetically separabl cJUN  a6524-65310 v43 a

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.

10aCobalt ferrite10aepoxidation10aFatty acids10amagnetic properties10ananocrystals1 aJeyavani, Vijayakrishnan1 aPawar, Sayali1 aDadwal, Arun1 aJoy, Pattayil, Alias1 aMukherjee, Shatabdi, Porel uhttps://library.ncl.res.in/content/size-controlled-cobalt-ferrite-nanocrystals-magnetically-separable-reusable-nanocatalysts