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Author: search.filters.author.Mahendra, K.Subject: search.filters.subject.Doping (additives)

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    Effect of Zn doping on the structural, optical, photoluminescence and mechanical properties of thiourea barium chloride (TBC) crystal
    (Elsevier Ltd, 2017) Mahendra, K.; D'Souza, A.; Udayashankar, N.K.
    In the present work, a synthesis and comparative study on the effect of Zinc (Zn) on thiourea barium chloride (TBC) single crystals has been reported. Crystals of thiourea barium chloride and Zn-doped thiourea barium chloride crystals are prepared using slow evaporation from the saturated solution. The samples were subjected to single crystal and powder X-ray diffraction to study the unitcell parameters and structural variations. The functional groups present in the crystals are derived using FTIR and Raman analysis. The enhancement of transmittance with the addition of Zn and the variations in the parameters such as bandgap, extinction coefficient, reflectance, refractive index, optical and electrical conductivity, real and imaginary part of dielectric constant are studied from UV–vis spectrum analysis. Vickers hardness measurements are conducted for pure and Zinc-doped TBC single crystals. The emission spectrum of pure and Zn doped single crystals are studied using photoluminescence analysis. © 2017 Elsevier Ltd
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    Enhanced structural, optical, thermal, mechanical and electrical properties by a noval approach (nanoparticle doping) on ferroelectric triglycine sulphate single crystal
    (Springer Verlag service@springer.de, 2019) Mahendra, K.; Kumar, H.K.T.; Udayashankar, N.K.
    The pristine and AgNP-doped TGS crystals are studied using powder X-ray diffraction, density measurements, solubility studies, UV–Vis analysis, photoluminescence spectroscopic analysis, thermal gravimetric analysis, differential thermal analysis, differential scanning calorimetry, Vicker’s hardness measurements, I–V and impedance measurements. From the XRD studies, TGS crystal formation is confirmed and by further analyzing X-ray diffraction data it is noticed that the incorporation of nanoparticles induce stress in the lattice of TGS crystal, which, in turn, lead to shift in peak positions. Crystal solubility and density values are increased after doping process. From the emission spectrum it is evident that emission intensity increases as the doping concentration increased. The melting point and mechanical hardness of the crystals also showed improvement after AgNP doping. Band gap calculated by Tauc’s relation is found to decrease with increase in doping concentration. Further, electrical studies demonstrated that crystal conductivity is improved as the doping concentration increases. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Modulations of physio-chemical and electronic properties of metalorganic KHO single crystals through Co(OH)2 nanoparticles doping
    (Springer New York LLC barbara.b.bertram@gsk.com, 2019) Mahendra, K.; Bhat, K.S.; Nagaraja, H.S.; Udayashankar, N.K.
    Semiorganic crystals play vital role in the design and development of optical devices. In this context, we report the synthesis of metalorganic potassium hydrogen oxalate oxalic acid dihydrate (KHO) single crystals using slow solvent evaporation technique. Further, Co(OH)2 nanoparticles pre-synthesized using hydrothermal method are doped to KHO single crystals. Doping of Co(OH)2 nanoparticles in the crystal system were confirmed through XRD, EDAX and PL measurements. The XRD measurements indicate a shift in the peak positions and variation in the overall intensities. On the other hand, PL measurements also indicate enhanced emission peaks confirming the successful doping of Co(OH)2 nanoparticles in the KHO system. As the effect of doping, the declination in the optical bandgap and improvement of electronic conductivity were also observed. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
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    Effect of methyl orange dye molecule on the structural, optical and electrical properties of the KHOOD single crystals
    (Springer, 2020) Mahendra, K.; Pujar, S.; Udayashankar, N.K.
    In the present investigation, synthesis of pristine and methyl orange dye-doped potassium hydrogen oxalate oxalic acid dihydrate (KHOOD) single crystals are reported. In this study, the structural properties of the crystals were investigated using powder XRD and the effect of dye incorporation on the KHOOD crystal was explored in detail. The effect of dye molecule on the optical absorption of the crystal was studied and the optical band gap was calculated using Tauc relation and presented in detail. Further, the effect on emission and mechanical properties of the crystals were also explored after doping with the dye molecule. Furthermore, the crystals were also studied electrically by subjecting to varying electrical frequencies (A.C) and the properties of pristine and doped crystals were compared and explained in detail. The modulus properties of the crystals were studied and compared. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Effect of Erioglaucine dye dopant on the structural, optical, mechanical, electrical and nonlinear properties of ammonium dihydrogen phosphate single crystal
    (Elsevier B.V., 2020) Fernandes, J.M.; Mahendra, K.; Udayashankar, N.K.
    The structural, optical, mechanical, electrical and nonlinear properties of standard Ammonium Dihydrogen Phosphate (NH4H2PO4, ADP) single crystals incorporating organic Erioglaucine dye dopant are presented. The effect of Erioglaucine dye dopant at varied concentration on these properties has been investigated through measurement of powder X-Ray Diffraction (XRD), UV–Vis and photoluminescence spectroscopy, Vickers microhardness, light dependent I–V measurements and Second Harmonic Generation studies. These measurements reveal that doping with increasing dye concentration of Erioglaucine leads to change in properties of the ADP single crystals, making them suitable for optoelectronic applications. The Erioglaucine doped ADP single crystals were grown using solvent evaporation technique at room temperature. Optical properties like absorbance and emission of these crystals are determined using UV–vis and photoluminescence spectroscopy, respectively. Optical bandgap and photoluminescence of the crystals are found to increase with dye doping, indicating their suitability in photonic applications. The mechanical properties of the crystals are determined using Vickers microhardness measurement technique. Light dependent I–V measurements exhibit negative photoconductivity behavior of the ADP crystals. However, the current through the crystals is observed to increase with increase in doping concentration of the Erioglaucine dye. Second Harmonic Generation studies show enhancement in nonlinearity for doped crystals. Our experiments indicate gradual variance in the crystallinity, emission, hardness, conductivity and nonlinearity of the sample with change in dye concentration. © 2020 Elsevier B.V.
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    An insight into noticeable dielectric response and effect of fe doping on photocatalytic efficiency (visible light) of ZnO nanoparticles synthesized through solution precipitation for harmful textile dye degradation
    (Springer Science and Business Media B.V., 2024) Mahendra, K.; Fernandes, J.M.; James, A.; B.s, N.; Pattar, J.; Sunitha, D.V.; Gopal, K.; Udayashankar, N.K.
    Iron (Fe)-incorporated zinc oxide (ZnO) nanoparticles (NPs) were synthesized via chemical precipitation technique and studied using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and UV–vis diffuse reflectance spectroscopy. PXRD analysis reveals a hexagonal wurtzite structure for all the synthesized samples. UV–visible measurements demonstrate a reduction in the bandgap of ZnO with an increase in Fe concentration. The ZnO and Fe-incorporated ZnO NPs are studied for the degradation of organic textile dye under visible light irradiation. All the nanoparticles are thoroughly investigated using impedance and dielectric measurements in the frequency range of 20 Hz to 1 MHz. The results obtained are compared, interpreted, and presented in this paper. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.