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Start Over Author "Devi, S." Publisher elsevier b.v.
190 results on '"Devi, S."'

44. Improved Haacke's quality factor, third order nonlinear susceptibility and specific capacitance realized for PbS thin films through La3+ doping.

Author

Chitra Devi, S., Sowmiya Devi, B., Balu, A.R., Devendran, K., Suganya, M., and Sriramraj, M.

Subjects
*THIN films, *QUALITY factor, *ELECTRIC capacity, *ELECTRON-hole recombination, *BAND gaps, *CARBON foams
Abstract

The present study examines the third order NLO and electrochemical properties of spray deposited lanthanum doped PbS (PbS:La) thin films. FCC crystallization was confirmed by XRD patterns along the plane (2 0 0). PbS crystallites vary in size between 27 and 36 nm with La doping concentration. Surface morphology improved with La doping. La doping increases the band gap from 1.97 to 2.18 eV. Near band edge (NBE) emissions in PL spectra originates from electron-hole recombination. A low resistivity of 0.23 x10−3 Ω-m was realized for PbS film doped with 4 wt% La concentration. Figure of merit of pure PbS improves from 1.32 x 10−3 Ω−1 to 1.607 x 10−2 Ω−1 with La doping. La doping modifies the energy states and band gap of PbS favouring strong nonlinear optical absorption. PbS:La thin films demonstrate self-defocusing due to temperature effects caused by absorption of single photons or free carriers. As a result of the low cationic field strength and high polarizability of La3+ ions, PbS exhibits a higher nonlinear refractive index. The nonlinear susceptibility and refractive index were found to be in the range 3.23–5.33 x 10−6 esu and 2.74 to 3.64 x 10−9 cm2/W, respectively. From the electrochemical studies, increased specific capacitance (256.46 F/g) and decreased charge transfer resistance (12 x 103 Ω) was observed for the 4 wt% La doped film. [ABSTRACT FROM AUTHOR]

Published
2023
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48. Improved photocatalytic, antimicrobial and photoelectrochemical properties of nanocrystalline Cu2+-doped ZnO nanoparticles.

Author

Umashankar, Raksha, Harshitha Devi, S., Gurushantha, K., Manjunatha, S.O., Al-Dossari, M., Shobha, G., Rudresh Kumar, K.J., Suresh Kumar, M.R., Keshavamurthy, K., Abd EL-Gawaad, N.S., Madhu, A., Satyanarayana Reddy, S., and Srinatha, N.

Subjects
*BAND gaps, *PHOTOCATALYSTS, *X-ray diffraction, *NANOPARTICLES, *DOPING agents (Chemistry), *ZINC oxide
Abstract

Herein we present the first report on the synthesis of Cu2+-doped ZnO nanoparticles via the solution-combustion using a new fuel (Glutamine). Systematic studies were carried out to assess the influence of Cu2+-concentration on photocatalytic, antimicrobial, and photoelectrochemical characteristics through various characterizations such as XRD, SEM-EDS, FTIR, UV–Visible, photocatalytic, antimicrobial, photoelectrochemical and Photoluminescence. XRD results show the formation of single-phase nanocrystalline particles and the substitution of Cu2+ at the Zn2+ site without the occurrence of impurity phases. SEM & EDS analysis revealed almost spherical particles and nominal (measured and experimental) element compositions. The structural changes induced due to the substitution of Cu2+ into the ZnO host lattice are evident in FTIR data, which show the presence of stretched ZnO bonds. The band gap narrowing effect was observed up to 5 mol% Cu2+ and thereafter band gap widens. PL spectra exhibit multiple emission peaks related to defects present in the host ZnO induced by the Cu2+ & PL intensity increases with the increase of doping concentration up to 3 mol % of Cu2+ beyond that its decreases with increasing concentration. The prepared NPs demonstrate promising photocatalytic activity against MB dye in both the UV and visible ranges. The maximum 94% percentage degradation was recorded for 9 mol% CuZnO, which is the highest among CuZnO NPs reported to date. In addition, 3 mol% and 2 mol% CuZnO NPs have shown potential antimicrobial activity against Bacillus and Pseudomonas respectively. The possible mechanism for both photocatalytic activity and antimicrobial activity is demonstrated. Furthermore, 5 mol% CuZnO has shown the largest transient photocurrent of 1.147 mA/cm2, which is ∼12 times larger than undoped ZnO (0.096 mA/cm2) due to the band-gap narrowing, suggests the possibility of photoelectrochemical sensors. [ABSTRACT FROM AUTHOR]

Published
2023
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