Department of Physics

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Physics

A potent semiorganic third order acentric crystal Poly[μ-chlorido-heptachlorido-μ3-L-proline-μ2-L-proline-tetramercury(II)] (LPDMCl) with the chemical formula [Hg4Cl8(C5H9NO2)2]n was crystallized by slow evaporation in water and thereby its second and third order optical nonlinearities are explored using the technique of SHG powder test of Kurtz-Perry and Z-scan single beam respectively. The grown crystalline material was analyzed by single crystal XRD, which discloses the acentric space group P1 of the material with the crystal system of triclinic. From XRD analysis, the obtained peaks were indexed correlated to the orientations of (hkl) plane thus displaying the crystalline purity and perfection. FTIR spectrum detailed the diverse vibrational modes, which signifies the functional groups in LPDMCl. Surface topology of the crystallized salts was accomplished by the examination of SEM. Mechanical, dielectric, linear and nonlinear optical investigation were performed to affirm LPDMCl as an aspiring candidate in establishing proficient nonlinear optical and optical power limiting device for practical applications. © 2020 Elsevier B.V.

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Department of Digital Communications

School of Information Technology and Engineering

Vellore Campus

School of Advanced Sciences

Chennai Campus

Physica B: Condensed Matter

Spectral, dielectric, mechanical and optical characteristics of LPDMCl single crystal for nonlinear optical applications

We report the structural, magnetic and electronic properties of a new compound YbFe2As2 based on our experimental studies and spin polarized density functional theory (DFT) calculations. X-ray diffraction measurements on the crushed crystals of YbFe2As2 shows monoclinic unit cell structure. Our electronic structure calculations were based on the Perdew-Burke Ernzerhof method (PBE + U) to treat the strong correlation effects between the 3d and 4f electrons of the Fe and Yb atoms respectively. The calculated partial density of states reveal that the hybridization between Yb-4f and Fe-3d states lead to these strong electron-correlation effects, which could provide a plausible explanation for the breaking of a possible antiferromagnetic order into small regions of ferromagnetic correlations contributed by the Fe atoms. This conjecture seems to be in agreement with our magnetization and electrical resistivity results. The density of states (DOS) reveals a metallic behaviour, which is also in agreement with the electrical resistivity measurements. The electronic band structure of YbFe2As2 depicts that in addition to high dispersion bands in the conduction band region, there are flat bands at the Fermi region composed of As-4p states and Fe-3d states. © 2019 Elsevier B.V.

VIT Unitversity

Chemistry

Journal of Magnetism and Magnetic Materials

Physical properties and electronic structure of YbFe2As2

Novel organic nonlinear optical material; p-Toluidinium malonate (PTM) was grown from aqueous solution by slow evaporation technique. The lattice parameters were evaluated from single crystal X-ray diffraction analysis and found that crystal system belongs to monoclinic with centrosymmetric space group P21/c. The solid state parameters; valence electrons, Plasma energy, Penn gap and Fermi energy were evaluated theoretically. These estimated values are used to calculate the electronic polarizability of PTM crystal. The functional groups exist in the compound were identified using FT-IR and FT-RAMAN spectroscopy. PTM crystal showed transmittance in the entire visible region with lower cut off wavelength of 311 nm and band gap energy of 3.8 eV. The photoluminescence spectrum was recorded to explore the emission and thermal behaviour of PTM crystal by employing TG/DTA analysis. Dielectric measurement was carried out on the grown crystal at different temperatures to evaluate electrical properties. The third-order nonlinear optical parameters were estimated by Z-scan technique using 532 nm diode pumped CW Nd:YAG Laser. © 2019 Elsevier B.V.

Department of Software Systems

School of Computer Science and Engineering

Journal of Molecular Structure

Synthesis, structural, growth, optical, electrical, thermal and third order nonlinear optical properties of a novel organic single crystal: p -Toluidinium malonate

Solution growth technique was used to harvest nonlinear optical 2-aminopyridine copper sulphate (2APCS) crystal at room temperature. Crystallinity in 2APCS crystal was confirmed by powder XRD. Single XRD study reveals 2APCS crystallizes in triclinic system. Band assignments of synthesized compound were identified using FT-IR study. Linear optical study shows lower cut-off wavelength 237 nm for 2APCS. Mechanical behavior study of 2APCS crystal posses soft nature of the sample. Third harmonic generation (THG) study was analyzed using Z-scan Technique for 2-aminopyridine copper sulphate (2APCS) crystal. In-vitro antibacterial test was carriedout for the 2APCS sample using test pathogenic bacteria, Escherichia coli (MTCC 443), S.aureus (MTCC 96) and E.faecalis (MTCC 439) were tested to find the antimicrobial activity. © 2019 Elsevier B.V.

Fulltext

Chemical Data Collections

Data on in-vitro antibacterial activity and third order NLO property of 2-aminopyridine copper sulphate (2APCS)

Glycine and its related compounds play a prominent role in the field of nonlinear optical studies and of fibre optical communication. In the present work, glycine sodium nitrate (GSN) crystal was grown using the method of slow evaporation method. The GSN crystal belongs to space group Cc in the monoclinic system. Using the FTIR spectrophotometer, the different functional groups have been qualitatively identified. A UV–Vis–NIR spectroscopy was used to record the optical absorption spectra, and the optical energy bandgap of GSN crystal is reported. The SHG conversion efficiency of GSN is determined by Kurtz and Perry technique. The Z-scan experiment was conducted to analyze GSN crystal for third-order NLO behavior and it is used to calculate the values of the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility. Third-generation harmonic studies reveal that GSN is an excellent material useful in the fabrication of NLO devices due to its nonlinear response characteristics. The thermal stability of the grown crystal was determined through TG/DTA examination. Also photoconductivity studies confirm the negative photoconductive behavior of GSN and I–V characteristics measurement that have been carried out. The dielectric loss is significantly low and this supports defect-free growth of the crystal. These properties of GSN make it a good candidate in the fabrication of NLO devices. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Electronics

Synthesis, growth, optical and third-order nonlinear optical properties of glycine sodium nitrate single crystal for photonic device applications

Slow evaporation technique has been employed to grow single crystals of cyclohexylammonium cinnamate (CYHC). The presence of functional groups was analyzed via Fourier transform infrared spectroscopy, and the single-crystal x-ray diffraction analysis confirmed P21/n symmetry in the crystal. Thermal analysis confirmed the melting point of the single crystal at 175.12°C and decomposition mechanism. The dielectric studies of CYHC were analyzed, and the activation energy of the sample was also estimated. The photoluminescence (PL) spectrum of CYHC shows the emission wavelength at 500 nm (green emission region), and chemical etching studies were carried out to investigate the surface quality of CYHC crystal. Third-order nonlinear and optical limiting studies were performed, and the values of threshold output and clamping output were found to be 18.62 mW and 1.72 mW, respectively. © 2020, The Minerals, Metals & Materials Society.

Journal of Electronic Materials

Cyclohexylammonium Cinnamate Single Crystal for Nonlinear Optical Applications

Two cocrystals of 18-crown-6 with isophthalic acid derivatives, 5-hydroxyisophthalic acid and trimesic acid, have been successfully grown by the slow evaporation solution growth technique. Crystal structures of (18-crown-6)·6(5-hydroxyisophthalic acid)·10(H2O) (I) and (18-crown-6)·2(trimesic acid)·2(H2O) (II) elucidated by single crystal X-ray diffraction reveal that both cocrystals pack the centrosymmetric triclinic space group . The molecules are associated by strong/weak hydrogen bonds, π⋯π and H⋯H stacking interactions. Powder X-ray diffraction analyses, experimental and simulated from single-crystal diffractogram data have been matched. The vibrational patterns in FT-IR spectra are used to identify the functional groups. The band gap energy is estimated by the application of the Kubelka-Munk algorithm. Hirshfeld surfaces derived from X-ray diffraction analysis reveal the type of molecular interactions and their relative contributions. The constructed supramolecular assembly of crown ether cocrystal is thoroughly described. Both cocrystals exhibit a significant third-order nonlinear optical response and it is observed that (I) possesses a significant first-order molecular hyperpolarizability whereas it is negligible for (II). © 2020 International Union of Crystallography.

Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

Supramolecular cocrystals of O - H⋯O hydrogen-bonded 18-crown-6 with isophthalic acid derivatives: Hirshfeld surface analysis and third-order nonlinear optical properties

Si/PVA-PEG polymer nanocomposites wereprepared by solvent casting method. XRD studies revealed the encapsulation of silicon in polymer matrix. Further crystalline behaviour of silicon in the polymer nanocomposites has been investigated. The size and morphological structure have been analysed with SEM. SEM showed the formation of homogeneous between PVA and PEG. FTIR confirmed the presence of silicon and various vibrational bonding natures. Band gap and refractive index of composites have been calculated from optical studies. Z-Scan analysis has been carried out at 532 nm which reveals optical non linearity of Si/PVA-PEG. © 2020, S.C. Virtual Company of Phisics S.R.L. All rights reserved.

Journal of Ovonic Research

Synthesis, characterization and nonlinear optical properties of si/pva-peg nanocomposites

Slow evaporation solution growth technique was adopted to grow good quality urea salicylic acid (USA) single crystals. Single-crystal X-ray diffraction confirmed their cell parameters and corresponding space group. Density functional theory (DFT) calculation was utilized to assess the frontier molecular orbital (FMO) and natural bonding orbitals (NBO) of the USA compound. Theoretically calculated bandgap energy was slightly different from the measured value of 3.49 eV and is utilized in understanding the charge transfer taking place in the molecule. The sample showed a lower cutoff wavelength of 350 nm. FTIR confirmed the presence of relevant functional groups and was found to be thermally stable up to 117 °C. The specific heat capacity of the title compound was found to be 1.28 J/kg/K at 30 °C. Laser damage threshold energy of USA crystal was found to be 1.37 GW/cm2. The electrical behaviour of the crystal was analysed from dielectric measurements. The mechanical stability revealed that the title compound is a soft material. Third-order nonlinear optical property of USA compound was analysed using standard Z-scan technique, which showed better characteristics compared to various reported comparable crystals. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Experimental and computational studies on third-order urea salicylic acid single crystal for optoelectronic device applications

This review deals with the growth and characterization of various urea and urea derivative single crystals. Samples grown by various methods like slow evaporation, low temperature solution growth, slow cooling, and mechanical direction limitation method from aqueous solution have been discussed. Various properties of these samples have been summarized. Considering that numerous works have been carried out on urea-based crystals, this review is confined to urea and organic derivatives of urea single crystals only. Improved non-linear optical properties of certain urea crystals have been highlighted in this article. © 2020, Sociedade Brasileira de Física.