Department of Physics

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Author: search.filters.author.Nair, Sindhu S.Has files: No

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Now showing 1 - 10 of 28
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    Enhancement of electrochemical reversibility in Poly 3-hexylthiophene layers for flexible dynamic glass windows applications
    (Elsevier, 2024-06) Nair, Sindhu S.
    Thin films of Poly 3-hexylthiophene (P3HT) were deposited onto Indium Tin Oxide (ITO) coated glass substrates using a spin coating method and the films were vacuum annealed at different temperatures to study the effect of annealing on the electrochemical reversibility. From the absorption spectra, the variation of the optical band gap with annealing temperature was studied for different annealing temperatures. The optical band gap obtained for P3HT film deposited at room temperature (RT) was around 1.94 eV and 1.92 eV for the sample annealed at 100 °C. A cyclic voltammetry (CV) analysis showed that at certain applied redox potentials, P3HT thin films changed the colour from magenta to transparent and then back to magenta in the reverse potential. P3HT films annealed at 100 °C showed the best electrochemical reversibility among all the annealed samples. These electrically switchable electrochromic P3HT thin films can be used in flexible dynamic windows (FDWs) as smart windows for controlling the temperature and light in buildings, displays and mirror light modulators.
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    Zinc based organic metal complexes for OLED applications
    (Elsevier, 2026-01) Nair, Sindhu S.
    Zinc-based organic metal complexes have emerged as promising materials for next-generation organic light-emitting diode (OLED) applications due to their unique electronic structure, environmental safety, and cost-effectiveness. Unlike traditional phosphorescent or thermally activated delayed fluorescence (TADF) emitters, Zn(II) complexes operate via ligand-centered (LC) and ligand-to-ligand charge transfer (LLCT) transitions, enabling precise color tuning without relying on heavy metals. These materials have a theoretical internal quantum efficiency cap of 25 %. Yet, they are compatible with solution-based production, thermally stable, easy synthesis, low toxicity, and relatively low-cost production, making them appealing for sustainable optoelectronic technologies. This review systematically examines Zn(II) complexes categorized by emission color, including blue, green, yellow, red, and white. It also highlights the molecular design strategies that influence their photophysical properties and device performance. We emphasize the relationship between molecular structure, electronic behavior, and OLED functionality to guide the rational design of new Zn-based emitters. These insights lay the groundwork for future research into sustainable, high-performance OLED materials, highlighting Zn(II) complexes as a promising route toward scalable, low-toxicity optoelectronic technologies.
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    Higher order elastic constants and generalized Gruneisen parameters of elastic waves and low temperature thermal expansion of gadolinium
    (Springer, 1996-12) Nair, Sindhu S.
    Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in gadolinium. The higher order elastic constants are used to find out the generalized Gruneisen parameters of the elastic waves propagating in different directions in gadolinium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.
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    Fourth order nonlinear elastic coefficients of hexagonal close packed lattice
    (Elsevier, 1996-09) Nair, Sindhu S.
    The expressions for the fourth-order elastic constants of a hexagonal close packed lattice is derived using the sublattice displacements to the second order in strains. These expressions together with the expressions for the second- and third-order elastic constants have been used to obtain the higher order nonlinear elastic coefficients in some hexagonal metals. These expressions are used to find the second-order, third-order and fourth-order elastic constants of cadmium. The pressure derivatives of their elastic constants are also obtained. The results obtained are compared with the available experimental results.
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    Higher order elastic constants and second pressure derivatives of zirconium
    (IAEA, 1997) Nair, Sindhu S.
    Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in strains. These expressions together with the expressions for the second and third order elastic constants have been used to obtain the higher order elastic constants and the pressure derivatives to second order elastic constants of hexagonal zirconium. The results obtained are compared with the reported values. The second pressure derivatives of zirconium are also reported
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    Higher Order Elastic Constants and Generalized Gruneisen Parameters of Elastic Waves and Low Temperature Thermal Expansion of Titanium
    (Elsevier, 1997-02) Nair, Sindhu S.
    The expressions for the 19 fourth order elastic constants, 10 third order elastic constants, and 6 second order elastic constants of a solid are derived using the method of homogenous deformation with interactions extending up to second neighbors using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in titanium. Titanium belongs to the hexagonal class of crystals. The higher order elastic constants are used to find the generalized Gruneisen parameters of the elastic waves propagating in different directions in titanium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.
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    Higher order elastic constants and generalised gruneisen parameters of elastic waves and low temperature thermal expansion of dysprosium
    (Elsevier, 1997-12) Nair, Sindhu S.
    The expressions for the 19 fourth order elastic constants, 10 third order elastic constants and six second order elastic constants are derived using the method of homogenous deformation with interactions extending up to second neighbours using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in dysprosium. Dysprosium belongs to the hexagonal class of crystals. The higher order elastic constants are used to find out the generalised Gruneisen parameters of the elastic waves propagating in different directions in dysprosium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.
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    Third-order elastic constants and low-temperature lattice thermal expansion of the high-temperature structural material TiAl
    (IOP, 2001) Nair, Sindhu S.
    We have derived the expressions for the 12 third-order elastic constants for a tetragonal system by the method of homogeneous deformation which are used to determine the third-order elastic constants of TiAl. These third-order elastic constants are used to determine the low-temperature limit of the volume thermal expansion of TiAl. The value of C333 was calculated to be a high value. The high value of the third-order elastic constant C333 shows a marked anisotropy in the crystal. The low-temperature limit is found to be negative, indicating a negative volume thermal expansion down to zero kelvin.
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    Micromagnetic simulations of the domain structure and the magnetization reversal of Co50Ni50/Pt multilayer dots
    (Elsevier, 2002-01) Nair, Sindhu S.
    The domain structure and the switching field of Co50Ni50/Pt multilayer dots, prepared by laser interference lithography, were micromagnetically simulated. The simulations were carried out with a three-dimensional simulation package, optimized for large-scale problems. The single-domain state is the lowest energy state for dots with a diameter below 75 nm. The switching field was computed by using suitable minimization techniques, and was used to analyze the effect of size, dot shape and edge defects.
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    A Photoemission study of CoO films on Au (111) Surface Science
    (Elsevier, 2003-09) Nair, Sindhu S.
    Angle-resolved ultraviolet photoemission spectroscopy has been used to study thin layers of Co and CoO on an Au(1 1 1) substrate. A bulk-like CoO layer was obtained for a nominal coverage of 7 ML Co, with Co evaporated in an oxygen atmosphere of 10−4 Pa and the Au(1 1 1) substrate at 350 K. Low-energy electron diffraction of this layer exhibits a (1 × 1) structure, indicating an unreconstructed CoO(1 1 1) surface. Considering the instability of a bulk-like terminated CoO surface, we assume stabilization by OH termination. At low coverage, the CoO layer is oxygen deficient and exhibits metallic character. For the bulk-like CoO layers we found band-like oxygen states and no detectable dispersion for the states near the Fermi edge, which is in agreement with previous investigations of single-crystalline CoO.