Now showing 1 - 4 of 4
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    Publication
    Plasmon enhanced visible light photocatalytic activity in polymer-derived TiN/Si-O-C-N nanocomposites
    (05-11-2018)
    Awin, Eranezhuth Wasan
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    Lale, Abhijeet
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    Demirci, Umit B.
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    Bernard, Samuel
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    Herein, we provide a detailed insight into the precursor chemistry, precursor-to-material transformation and characterization of nanocomposites made of a TiN nanophase and a Si-O-C-N ceramic. The polymer-derived ceramics (PDCs) route applied to synthesize these nanocomposites resulted in the formation of nanocrystals less than 4 nm in size and the calculated lattice parameter value for the nanocrystals (a = 0.4239 nm) matched the theoretical value of TiN (a = 0.4241 nm). The Si-O-C-N ceramic served as a platform for anchoring TiN nanocrystals. As a proof of concept, we have attempted to exploit the plasmonic properties of nanocomposites to achieve photocatalytic degradation of organic dyes. The absorption spectra clearly showed plasmonic resonance in the visible region with peak positioned around 670 nm according to the presence of TiN nanocrystals which resulted in the enhancement of dye degradation.
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    Publication
    Low frequency dielectric behavior and AC conductivity of polymer derived SiC(O)/HfCxN1-x ceramic nanocomposites
    (15-02-2021)
    Awin, Eranezhuth Wasan
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    Sridar, Soumya
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    Kousaalya, Adhimoolam Bakthavachalam
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    Vendra, S. S.Lokesh
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    Koroleva, Ekaterina
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    Filimonov, Alexey
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    Vakhrushev, Sergey
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    The dielectric behavior of spark plasma sintered SiC(O)/HfCxN1-x nanocomposites synthesized through polymer derived ceramic route was investigated in the frequency range of 1 kHz to 1 MHz at room temperature. The nanostructural features revealed HfCxN1-x nanocrystals encapsulated in a nanometric thin layer of carbon dispersed uniformly in a SiC(O) matrix with segregated free carbon. The nanocomposites exhibited colossal permittivity values in the order of 103 at 1 kHz which reduced to 646 at 1 MHz. The interfacial polarization mechanism existing between complex nanostructural interfaces and the percolation of HfCxN1-x nanocrystals are believed to be responsible for the high permittivity values observed in the measured frequency range. The AC conductivity exemplified a frequency independent behavior at lower frequencies while at higher frequencies, the conductivity exhibited frequency dependence, indicating the existence of hopping type mechanism.
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    Publication
    TiNb2O7-Keratin derived carbon nanocomposites as novel anode materials for high-capacity lithium-ion batteries
    (01-06-2021)
    Thiyagarajan, Ganesh Babu
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    Shanmugam, Vasu
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    Wilhelm, Michael
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    Mathur, Sanjay
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    Moodakare, Sahana B.
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    TiNb2O7/carbon nanocomposites synthesized through a simple, surfactant assisted precursor route is reported as a promising alternative anode material for lithium-ion batteries (LIBs). The carbon component of the nanocomposites is derived from an inexpensive and sustainable keratin rich biological source. The reinforcement of carbon in TiNb2O7 facilitated the formation of non-stoichiometric (Ti0.712Nb0.288)O2 crystalline phase, in addition to the stoichiometric TiNb2O7 phase. It also yielded a high specific surface area (~90 ​m2 ​g−1) and reduced crystallite size (~4 ​nm). Electrochemical results exemplified high reversible capacity of 356 mAh g−1 at 0.1 ​C and remarkable rate capability of ~26 mAh g−1 at ultra-high current rate of 32C. TiNb2O7/carbon nanocomposites also demonstrated remarkable cyclic stability with large capacity retention of 85% even after 50 cycles at 1 ​C. The experimental data attests the potential of TiNb2O7/keratin derived carbon nanocomposites as economically and environmentally viable promising anode material for LIBs.
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    Publication
    Effect of interface carbonization on dielectric properties of potassium nitrate nanocomposite based on porous glasses
    (01-08-2022)
    Molokov, A.
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    Sysoeva, A.
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    Naberezhnov, A.
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    Koroleva, E.
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    Vakhrushev, S.
    Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm (PG6) with embedded KNO3 have been studied at the temperature diapason of 300-430 K and at frequencies of 0.1-3 × 106 Hz on cooling. X-ray diffraction studies of these samples have shown, that in modified and unmodified composites there is a mixture of the low-temperature paraelectric phase (α-phase) and the ferroelectric γ-phase. In modified composites, a decrease in permittivity and conductivity is observed. Dielectric response has been analyzed in the framework of modern theoretical models. Two relaxation processes have been identified and their origin has been determined. It has been found that the main contribution to the dielectric response of nanocomposite material PG6+KNO3 is provided by charge polarization on interfaces, which can be governed by modifying the inner pore surfaces. DC-conductivity of both composites has been estimated and the activation energies have been determined. Activation energy change observed in a vicinity of 360 K is attributed to the phase transformation and the appearance of KNO3 α-phase.