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Author: search.filters.author.Bindu, K.Subject: search.filters.subject.Tin compounds

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    Hydrothermally synthesized reduced graphene oxide and Sn doped manganese dioxide nanocomposites for supercapacitors and dopamine sensors
    (Elsevier Ltd, 2017) Shanbhag, D.; Bindu, K.; Aarathy, A.R.; Ramesh, R.; Moolayadukkam, M.; Nagaraja, H.S.
    ?-MnO2 nanowires and its nanocomposites (rGO-MnO2 and Sn@rGO-MnO2) were synthesized by a facile hydrothermal technique. Two important electrochemical applications of nanocomposites, viz, electrodes for supercapacitor and sensors for a biomolecule, dopamine are reported. The prepared nanowires have been characterized by XRD, which reveals smaller crystallite size of rGO- MnO2 composites compared to pristine MnO2 and the trend is supported by BET analysis. The wrapping of MnO2 NWs with rGO sheets increases the surface area, as well as, creates more dislocations at the interfaces. The correlation between physicochemical properties leads to an enhancement in the electrochemical performance of the materials. The as-fabricated Sn@rGO-MnO2 supercapacitor electrode reveals superior performance. The specific capacitance of 139.05, 309.7 and 460.9 F/g at a scanning rate of 20 mV/s, in an aqueous Na2SO4 solution (1 M) is obtained for MnO2, rGO-MnO2 and Sn@rGO-MnO2 respectively. Also, the reported nanocomposites show excellent performance towards detection of dopamine. Among ?-MnO2/GCE, rGO-MnO2/GCE and Sn@rGO-MnO2/GCE based sensors for Dopamine detection, rGO-MnO2/GCE sensor exhibits the highest sensitivity of 433.6 ?A/mM and broad linear range, whereas Sn@rGO-MnO2 exhibits lower detection limit of 0.13 ?M. © 2017 Elsevier Ltd
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    Electrical, dielectric and magnetic properties of Sn-doped hematite (?-SnxFe2-xO3) nanoplates synthesized by microwave-assisted method
    (Elsevier Ltd, 2018) Bindu, K.; Ajith, K.M.; Nagaraja, H.S.
    Hematite nanoparticles are of interest due to their exceptional electrical and magnetic behavior and various technological applications. The doping of hematite can vary its electrical and magnetic properties. Here, we report the effect of different concentrations of Tin doping on electrical, dielectric and magnetic properties of hematite synthesized by the microwave-assisted method. Tin-doped ?- Fe2O3 (?-SnxFe2-xO3) samples have been characterized using XRD, TGA, FESEM, and EDS (mapping). XRD pattern shows the rhombohedral structure of ?-SnxFe2-xO3. The synthesized samples have nanoplate like structure with a uniform distribution of tin throughout the sample. Electrical properties were investigated using dielectric and impedance studies. The dc resistivity and ac conductivity decreased with increase in concentration up to x = 0.06 (Sn0.06Fe1.94O3). However, it increased with further increase in the concentration of tin. The hopping of electrons between Fe3+ and Fe2+ in octahedral sites accounts for the observed conduction behavior. A single semi-circle of the cole-cole plot for ?-SnxFe2-xO3 indicates the dominant grain boundary effect in conduction. Dielectric constant and loss factor reveal the dielectric relaxation in ?-SnxFe2-xO3 samples. The magnetic properties were studied using VSM, which shows that ?-SnxFe2-xO3 are antiferromagnetic/weakly ferromagnetic in nature with high coercivity. © 2017 Elsevier B.V.
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    Influence of cations on the dielectric properties of spinel structured nanoferrites
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Bindu, K.; Ajith, K.M.; Nagaraja, H.S.
    MFe2O4 (M: Fe, Zn, Ni and Sn) nanoparticles were prepared using single step hydrothermal method. Their structural, compositional and dielectric properties have been studied to investigate the effect of cations on spinel ferrites. XRD confirms the spinel structure of the samples with substitution of Zn, Ni and Sn in the lattice sites of Fe. FTIR spectra of all samples have characteristic ?1 and ?2 bands. SEM and EDS mapping show uniform distribution of cations throughout the samples. ZnFe2O4 and SnFe2O4 have higher ac conductivity and dielectric constant than that of Fe3O4 and NiFe2O4, which can be attributed to the different cationic distribution in the spinel structure. © 2019 IOP Publishing Ltd.
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    Influence of cations in MFe2O4 (M: Fe, Zn, Ni, Sn) ferrite nanoparticles on the electrocatalytic activity for application in hydrogen peroxide sensor
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Bindu, K.; Nagaraja, H.S.
    Hydrothermally prepared MFe2O4 (M: Fe, Zn, Ni and Sn) nanoparticles have been characterized by XRD, SEM and BET. The ferrite nanoparticles have been tested for their electrocatalytic activity and application towards the reduction and sensing of hydrogen peroxide using cyclic voltammetry and chronoamperometry techniques. ZnFe2O4 and SnFe2O4 reveal superior H2O2 sensing performance than Fe3O4 and NiFe2O4, which can be attributed to the lower redox potential of Sn2+/Sn4+ couple, lower charge-transfer resistance and higher specific surface area. ZnFe2O4 and SnFe2O4 have a sensitivity of 4.411 and 3.915 ?AmM-1 ?g-1, respectively, which is greater than that of Fe3O4 (0.434 ?AmM-1 ?g-1) and NiFe2O4 (0.644 ?AmM-1 ?g-1). SnFe2O4 has the lowest limit of detection (2.6 (M) with good selectivity towards H2O2 in the presence of other interference agents. © 2019 IOP Publishing Ltd.