02118nas a2200217 4500008004100000022001400041245009100055210006900146260008000215300001400295490000700309520130500316100001901621700002201640700001901662700002501681700001801706700002201724700003301746856012101779 2006 eng d a0957-448400aEvidence for intergranular tunnelling in polyaniline passivated alpha-Fe nanoparticles0 aEvidence for intergranular tunnelling in polyaniline passivated  aDIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLANDbIOP PUBLISHING LTDcSEP a4765-47720 v173 a

Nanoparticles are of immense importance both from the fundamental and application points of view. They exhibit quantum size effects which are manifested in their improved magnetic and electric properties. Mechanical attrition by high energy ball milling (HEBM) is a top down process for producing fine particles. However, fineness is associated with high surface area and hence is prone to oxidation which has a detrimental effect on the useful properties of these materials. Passivation of nanoparticles is known to inhibit surface oxidation. At the same time, coating polymer film on inorganic materials modifies the surface properties drastically. In this work a modified set-up consisting of an RF plasma polymerization technique is employed to coat a thin layer of a polymer film on Fe nanoparticles produced by HEBM. Ball-milled particles having different particle size ranges are coated with polyaniline. Their electrical properties are investigated by measuring the dc conductivity in the temperature range 10-300 K. The low temperature dc conductivity (I-V) exhibited nonlinearity. This nonlinearity observed is explained on the basis of the critical path model. There is clear-cut evidence for the occurrence of intergranular tunnelling. The results are presented here in this paper.

1 aSunny, Vijutha1 aNarayanan, T., N.1 aSajeev, U., S.1 aJoy, Pattayil, Alias1 aKumar, Sakthi1 aYoshida, Yasuhiko1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/evidence-intergranular-tunnelling-polyaniline-passivated-alpha-fe-nanoparticles-002159nas a2200229 4500008004100000022001400041245013600055210006900191260007300260300001400333490000800347520126000355653002701615100001901642700002101661700001901682700002501701700001801726700002201744700003301766856013001799 2009 eng d a0304-885300aImpact of zinc substitution on the structural and magnetic properties of chemically derived nanosized manganese zinc mixed ferrites0 aImpact of zinc substitution on the structural and magnetic prope aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a1092-10990 v3213 a

Mn(1-x)Zn(x)Fe(2)O(4) nanoparticles (x = 0-1) were synthesized by wet chemical co-precipitation techniques. X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy were effectively utilized to investigate the different structural parameters. The elemental analysis was conducted using energy-dispersive spectrum and inductively coupled plasma analysis. The magnetic properties such as magnetization and coercivity were measured using vibrating sample magnetometer. The observed magnetization values of the nanoparticles were found to be lower compared to the bulk counterpart. The magnetization showed a gradual decrease with zinc substitution except for a small increase from x = 0.2 to 0.3. The Curie temperature was found to be enhanced in the case of ferrites in the nanoregime. The variation in lattice constant, reduced magnetization values, variation of magnetization with zinc substitution, the presence of a net magnetic moment for the zinc ferrite and the enhancement in Curie temperature in Mn(1-x)Zn(x)Fe(2)O(4) all provide evidence to the existence of a metastable cation distribution together with possible surface effects at the nanoregime. (C) 2008 Elsevier B.V. All rights reserved.

10aManganese zinc ferrite1 aGopalan, Veena1 aAl-Omari, I., A.1 aMalini, K., A.1 aJoy, Pattayil, Alias1 aKumar, Sakthi1 aYoshida, Yasuhiko1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/impact-zinc-substitution-structural-and-magnetic-properties-chemically-derived-nanosized-002007nas a2200289 4500008004100000022001400041245010200055210006900157260006900226300001200295490000800307520093700315653002501252653002601277653003501303653001901338653005001357653002201407653002201429100001901451700002501470700002101495700001801516700002201534700003301556856012801589 2009 eng d a0925-838800aOn the structural, magnetic and electrical properties of sol-gel derived nanosized cobalt ferrite0 astructural magnetic and electrical properties of solgel derived  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT a711-7170 v4853 a

Nanoparticles of cobalt ferrite were synthesized by sol gel method. These particles were structurally characterized by using X-Ray Diffraction and Transmission Electron Microscopy, High Resolution Transmission Electron Microscopy, Energy Dispersive Spectrum and Inductively Coupled Plasma Analysis and the results confirmed the formation of spherically shaped nanoparticles of cobalt ferrite having a size lying in the range of 13-14 nm. The as prepared sample was sintered at 800 degrees C and the structural, magnetic and dielectric properties were measured. The dielectric properties were studied and analyzed as a function of temperature and frequency. The ac and dc conductivity studies were carried out to delve into the conduction mechanism. The existing models based on quantum mechanical tunneling were effectively employed to explain the frequency dependent conductivity. (C) 2009 Elsevier B.V. All rights reserved.

10aElectronic Transport10aMagnetic measurements10aMagnetically ordered materials10aNanostructures10aScanning and transmission electron microscopy10aSol-gel synthesis10aX-ray diffraction1 aGopalan, Veena1 aJoy, Pattayil, Alias1 aAl-Omari, I., A.1 aKumar, Sakthi1 aYoshida, Yasuhiko1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/structural-magnetic-and-electrical-properties-sol-gel-derived-nanosized-cobalt-ferrite-001464nas a2200205 4500008004100000022001400041245007800055210006900133260005700202300001200259490000700271520073000278100001901008700002101027700001801048700002201066700002501088700003301113856011201146 2010 eng d a0947-839600aInverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite0 aInverse magnetocaloric effect in solgel derived nanosized cobalt a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcMAY a497-5030 v993 a

The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol-gel combustion. The nanoparticles were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (Delta S (m)) calculated indirectly from magnetization isotherms in the temperature region 170-320 K was found to be negative, signifying an inverse magnetocaloric effect in the nanoparticles. The magnitudes of the Delta S (m) values were found to be larger when compared to the reported values in the literature for the corresponding ferrite materials in the nanoregime.

1 aGopalan, Veena1 aAl-Omari, I., A.1 aKumar, Sakthi1 aYoshida, Yasuhiko1 aJoy, Pattayil, Alias1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/inverse-magnetocaloric-effect-sol-gel-derived-nanosized-cobalt-ferrite-002649nas a2200301 4500008004100000022001400041245008800055210006900143260005700212300001200269490000600281520155900287653002501846653003301871653004201904653003801946653004001984100001902024700001902043700002202062700002202084700002502106700002102131700001802152700002202170700003302192856012202225 2010 eng d a1556-276X00aTemplate-assisted synthesis and characterization of passivated nickel nanoparticles0 aTemplateassisted synthesis and characterization of passivated ni a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcMAY a889-8970 v53 a

Potential applications of nickel nanoparticles demand the synthesis of self-protected nickel nanoparticles by different synthesis techniques. A novel and simple technique for the synthesis of self-protected nickel nanoparticles is realized by the inter-matrix synthesis of nickel nanoparticles by cation exchange reduction in two types of resins. Two different polymer templates namely strongly acidic cation exchange resins and weakly acidic cation exchange resins provided with cation exchange sites which can anchor metal cations by the ion exchange process are used. The nickel ions which are held at the cation exchange sites by ion fixation can be subsequently reduced to metal nanoparticles by using sodium borohydride as the reducing agent. The composites are cycled repeating the loading reduction cycle involved in the synthesis procedure. X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron microscopy, Energy Dispersive Spectrum, and Inductively Coupled Plasma Analysis are effectively utilized to investigate the different structural characteristics of the nanocomposites. The hysteresis loop parameters namely saturation magnetization and coercivity are measured using Vibrating Sample Magnetometer. The thermomagnetization study is also conducted to evaluate the Curie temperature values of the composites. The effect of cycling on the structural and magnetic characteristics of the two composites are dealt in detail. A comparison between the different characteristics of the two nanocomposites is also provided.

10aNickel nanoparticles10aPolymer-metal nanocomposites10aStrongly acidic cation exchange resin10aStuctural and magnetic properties10aWeakly acidic cation exchange resin1 aGopalan, Veena1 aMalini, K., A.1 aSanthoshkumar, G.1 aNarayanan, T., N.1 aJoy, Pattayil, Alias1 aAl-Omari, I., A.1 aKumar, Sakthi1 aYoshida, Yasuhiko1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/template-assisted-synthesis-and-characterization-passivated-nickel-nanoparticles-0