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-002114nas a2200277 4500008004100000022001400041245013400055210006900189260005700258300001400315490000600329520109600335653002101431653002601452653002401478653001501502653002301517100002701540700002201567700001901589700002001608700002201628700002501650700003301675856012801708 2010 eng d a1931-757300aSynthesis of bio-compatible SPION-based aqueous ferrofluids and evaluation of radiofrequency power loss for magnetic hyperthermia0 aSynthesis of biocompatible SPIONbased aqueous ferrofluids and ev a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcOCT a1706-17110 v53 a

Bio-compatible magnetic fluids having high saturation magnetization find immense applications in various biomedical fields. Aqueous ferrofluids of superparamagnetic iron oxide nanoparticles with narrow size distribution, high shelf life and good stability is realized by controlled chemical co-precipitation process. The crystal structure is verified by X-ray diffraction technique. Particle sizes are evaluated by employing Transmission electron microscopy. Room temperature and low-temperature magnetic measurements were carried out with Superconducting Quantum Interference Device. The fluid exhibits good magnetic response even at very high dilution (6.28 mg/cc). This is an advantage for biomedical applications, since only a small amount of iron is to be metabolised by body organs. Magnetic field induced transmission measurements carried out at photon energy of diode laser (670 nm) exhibited excellent linear dichroism. Based on the structural and magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of radiofrequencies.

10aMagnetic heating10aMagnetic hyperthermia10aMagnetic relaxation10aPower loss10aSuperparamagnetism1 aMary, Antony, P. Reena1 aNarayanan, T., N.1 aSunny, Vijutha1 aSakthikumar, D.1 aYoshida, Yasuhiko1 aJoy, Pattayil, Alias1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/synthesis-bio-compatible-spion-based-aqueous-ferrofluids-and-evaluation-radiofrequency-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-001742nas a2200241 4500008004100000022001400041245013100055210006900186260012500255300001100380490000800391520077200399100002101171700001501192700001901207700002101226700002201247700001801269700002501287700002501312700003301337856013001370 2013 eng d a0003-695100aContact potential induced enhancement of magnetization in polyaniline coated nanomagnetic iron oxides by plasma polymerization0 aContact potential induced enhancement of magnetization in polyan aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScOCT a1624140 v1033 a

The present work derives motivation from the so called surface/interfacial magnetism in core shell structures and commercial samples of Fe3O4 and gamma Fe2O3 with sizes ranging from 20 to 30 nm were coated with polyaniline using plasma polymerization and studied. The High Resolution Transmission Electron Microscopy images indicate a core shell structure after polyaniline coating and exhibited an increase in saturation magnetization by 2 emu/g. For confirmation, plasma polymerization was performed on maghemite nanoparticles which also exhibited an increase in saturation magnetization. This enhanced magnetization is rather surprising and the reason is found to be an interfacial phenomenon resulting from a contact potential. (C) 2013 AIP Publishing LLC.

1 aSethulakshmi, N.1 aSooraj, V.1 aSajeev, U., S.1 aNair, Swapna, S.1 aNarayanan, T., N.1 aJoy, Lija, K.1 aJoy, Pattayil, Alias1 aAjayan, Pulickel, M.1 aAnantharaman, Maliemadom, R. uhttps://library.ncl.res.in/content/contact-potential-induced-enhancement-magnetization-polyaniline-coated-nanomagnetic-iron-001909nas a2200205 4500008004100000022001400041245009600055210006900151260011000220300001600330490000700346520109400353100001801447700001701465700002201482700002201504700003001526700002201556856012501578 2015 eng d a1463-907600aFractional photo-current dependence of graphene quantum dots prepared from carbon nanotubes0 aFractional photocurrent dependence of graphene quantum dots prep aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a24566-245690 v173 a

We report on the photo-conductivity studies of chemically synthesized graphene quantum dots (GQDs) of average size 12 nm obtained by the oxidative acid treatment of MWCNTs. The dependence of photocurrent I-ph (I-ph = I-ill - I-dark) on the laser intensity P under a wide range of laser intensities (5 mW <= P <= 60 mW) shows a fractional power dependence of I-ph on light intensity. The temperature dependence (300 K < T < 50 K) of I-ph observed in thin films of these GQDs indicates that in the higher temperature region (T > similar to 100 K), as the temperature increases, the number of thermally generated carriers increase resulting in increased I-ph. At sufficiently low temperatures (T <= 100 K), a constant I-ph is observed, indicating a constant photocarrier density. Such a behavior is typically observed in many photoactive disordered semiconductors, which are often used in a variety of applications. We believe that the investigations presented here will enhance our understanding of the photocurrent generation phenomenon in chemically obtained GQDs.

1 aKundu, Sumana1 aGhosh, Sujoy1 aFralaide, Michael1 aNarayanan, T., N.1 aPillai, Vijayamohanan, K.1 aTalapatra, Saikat uhttps://library.ncl.res.in/content/fractional-photo-current-dependence-graphene-quantum-dots-prepared-carbon-nanotubes-001490nas a2200205 4500008004100000245005900041210005700100260000800157300001600165490000600181520084400187100001801031700002401049700002201073700002501095700001901120700002501139700003001164856009001194 2015 eng d00aSynthesis of N, F and S co-doped graphene quantum dots0 aSynthesis of N F and S codoped graphene quantum dots cMAY a11515-115190 v73 a

Graphene quantum dots (GQDs) are a promising category of materials with remarkable size dependent properties like tunable bandgap and photoluminescence along with the possibility of effective chemical functionalization. Doping of GQDs with heteroatoms is an interesting way of regulating their properties. Herein, we report a facile and scalable one-step synthesis of luminescent GQDs, substitutionally co-doped with N, F and S, of similar to 2 nm average size by a microwave treatment of multi-walled carbon nanotubes in a customized ionic liquid medium. The use of an ionic liquid coupled with the use of a microwave technique enables not only an ultrafast process for the synthesis of co-doped GQDs, but also provides excellent photoluminescence quantum yield (70%), perhaps due to the interaction of defect clusters and dopants.

1 aKundu, Sumana1 aYadav, Ram, Manohar1 aNarayanan, T., N.1 aShelke, Manjusha, V.1 aVajtai, Robert1 aAjayan, Pulickel, M.1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/synthesis-n-f-and-s-co-doped-graphene-quantum-dots