01907nas a2200217   4500008004100000022001400041245012100055210006900176260012500245300001100370490000800381520101800389100001901407700002001426700001901446700001601465700001901481700002501500700003301525856013101558       2014                        eng d  a0021-897900aFlexible microwave absorbers based on barium hexaferrite, carbon black, and nitrile rubber for 2-12 GHz applications0 aFlexible microwave absorbers based on barium hexaferrite carbon   aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScJUL  a0249020 v1163 a<p>Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2-12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding -20 dB is obtained for all the samples in a wide frequency range of 2-12 GHz when an appropriate absorber thickness between 5 and 9 mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties, and absorptivity. (C) 2014 AIP Publishing LLC.</p>1 aVinayasree, S.1 aSoloman, M., A.1 aSunny, Vijutha1 aMohanan, P.1 aKurian, Philip1 aJoy, Pattayil, Alias1 aAnantharaman, Maliemadom, R.  uhttp://library.ncl.res.in/content/flexible-microwave-absorbers-based-barium-hexaferrite-carbon-black-and-nitrile-rubber-2-12-001650nas a2200193   4500008004100000245012700041210006900168260000800237300002700245490000700272520093700279100001901216700001801235700001901253700001901272700001601291700002501307856012401332       2018                        eng d00aMagnetically tunable liquid dielectric with giant dielectric permittivity based on core-shell superparamagnetic iron oxide0 aMagnetically tunable liquid dielectric with giant dielectric per  cJUL  aArticle Number: 2657070 v293 aA liquid dielectric based on a core-shell architecture having a superparamagnetic iron oxide core and a shell of silicon dioxide was synthesized. The frequency dependence of dielectric properties was evaluated for different concentrations of iron oxide. The dependence of magnetic field on the dielectric properties was also studied. Aqueous ferrofluid exhibited a giant dielectric constant of 6.4 x 10(5) at 0.1 MHz at a concentration of 0.2 vol% and the loss tangent was 3. The large rise in dielectric constant at room temperature is modelled and explained using percolation theory and Maxwell-Wagner-Sillars type polarization. The ferrofluid is presumed to consist of nanocapacitor networks which are wired in series along the lateral direction and parallel along longitudinal direction. On the application of an external magnetic field, the chain formation and its alignment results in the variation of dielectric permittivity.1 aVinayasree, S.1 aNitha, T., S.1 aTiwary, C., S.1 aAjayan, P., M.1 aJoy, P., A.1 aAnantharaman, M., R.  uhttp://library.ncl.res.in/content/magnetically-tunable-liquid-dielectric-giant-dielectric-permittivity-based-core-shell02206nas a2200289   4500008004100000022001400041245010800055210006900163260000900232300001100241490000700252520125200259653001701511653002901528653001501557653003001572653002501602100001901627700003001646700001601676700002001692700001701712700001601729700001601745700002501761856013001786       2019                        eng d  a0957-448400aStealth emulsion based on natural rubber latex, core-shell ferrofluid/carbon black in the S and X bands0 aStealth emulsion based on natural rubber latex coreshell ferrofl  cAUG   a3157030 v303 a<p>A lossy dielectric with an appropriate magnetic property is one of the requirements of a stealth material. The thickness of the absorber and the corresponding bandwidth of absorption are also other deciding factors that determine the choice of the material as microwave absorbers. A stable emulsion, which is lossy as well as magnetic, is promising, since it can be coated on surfaces with required thickness in the desired band. A magnetic nanofluidic emulsion serves the purpose. A microwave absorbing emulsion based on natural rubber latex with core-shell magnetic nanoparticles, based on superparamagnetic iron oxide nanoparticles (SPIONs), was developed. The effect of additives like carbon black on the bandwidth of absorption was also studied as a function of weight percentage of carbon black. The complex dielectric permittivity and magnetic permeability were evaluated using a vector network analyser in the S and X bands. Furthermore, these results were modelled using surface impedance equations. These investigations revealed that the incorporation of carbon black enhances the bandwidth of absorption and an emulsion with the required dielectric permittivity and magnetic permeability can be tailored for stealth applications.</p>10acarbon black10acore-shell nanoparticles10aferrofluid10amicrowave absorbing paint10anatural rubber latex1 aVinayasree, S.1 aNair, Ajalesh, Balachandr1 aMani, Manoj1 aArchana, V., N.1 aJoseph, Rani1 aMohanan, P.1 aJoy, P., A.1 aAnantharaman, M., R.  uhttp://library.ncl.res.in/content/stealth-emulsion-based-natural-rubber-latex-core-shell-ferrofluidcarbon-black-s-and-x-bands