arXiv subjects

Sujoy Kumar Mandal

Publications and source records attributed to Sujoy Kumar Mandal.

3 recordsLinked to original sources

arXiv2022

One-Step Hydrothermal Synthesis of Sb 2 WO 6 Nanoparticle towards Excellent LED Light Driven Photocatalytic Dye Degradation

Pristine Antimony tungstate nanoparticles prepared via a simple hydrothermal process showcase interesting photocatalytic efficiency, degrading Methylene Blue (MB) completely in 180 min under visible light. In this study, the impact on crystalline quality and related optical properties as well as photocatalytic efficiency of antimony tungstate due to temperature variation during hydrothermal synthesis are explored. While X-ray diffraction (XRD) shows the polycrystalline nature of all synthesized samples, however a systematic increase in crystallite size is revealed by analysing the XRD peak broadening. XRD spectra are further examined by Rietveld analysis showing a change in unit cell volume. Additionally, the overall changes in the corresponding grain size and micro-strain developed in the crystals are determined using the Williamson-Hall plot. Moreover, significant variations in few Raman modes are observed with increasing synthesis temperature. A notable modification in the optical band gap as determined from the absorbance of the UV-Vis spectra is perceived with the change in synthesis temperature within the range of ~2.38-2.57 eV. Further, the photoluminescence measurement indicates that the synthesized antimony tungstate is weak luminescent material with a band-to-band emission at ~468 nm. Finally, photocatalytic efficiencies of the samples are ascertained to change with the synthesis parameter, estimated by decomposing methylene blue (MB), highest degradation rate constant (k) value is observed as 0.015 min -1 for the sample prepared at 180 o C. While the sample with the highest efficiency is also applied for degrading the Rhodamine B (RhB) and Potassium Dichromate (K 2 Cr 2 O 7 ) under visible light irradiation.

cond-mat.mtrl-sci↗

arXiv2021

Nitrogenated CQD decorated ZnO nanorods towards rapid photodegradation of rhodamine B: a combined experimental and theoretical approach

In this work, hybridization of nonmetal nitrogen-doped carbon dots (NCQDs) with ZnO nanorods (NRs) is utilized towards better photocatalytic degradation of rhodamine B under ultraviolet (UV) irradiation. The structural characterization is confirmed by XRD, XPS, FTIR and HRTEM measurements, while, optical properties have been investigated using UV-visible absorbance spectroscopy and photoluminescence study. The dye degradation using ZnO NR is recorded as ~69%, while the performance of ZnO/NCQD climbs up to ~90%, after nine minutes of UV irradiation. Furthermore, the reusability test suggests better stability of ZnO/NCQD than bare ZnO under photocorrosion. The cyclic voltammetry study confirms that the photoinduced electron-hole pairs originate from the heterojunction established between the interfaces of NCQD and ZnO. An insight on the photocatalytic excellence of ZnO/NCQD system is drawn from the density functional theory study. This indicates that appropriate band alignment of the heterostructure constituents is the key factor in this experimental attempt towards environment remedy.

cond-mat.mtrl-sci↗

arXiv2016

Are supersymmetric models with minimal particle content under tension for testing at LHC?

In supersymmetric models with minimal particle content and without large left-right squarks mixing, the conventional knowledge is that the Higgs Boson mass around 125 GeV leads to top squark masses ${\cal O}(10)$ TeV, far beyond the reach of colliders. Here, we pointed out that this conclusion is subject to several theoretical uncertainties. We find that electroweak symmetry breaking and evaluation of Higgs mass at a scale far away from the true electroweak symmetry breaking scale introduce a large uncertainty in Higgs mass calculation. We show that the electroweak symmetry breaking at the scale near the true vacuum expectation value of Higgs field can increase the Higgs Boson mass about 4-5 GeV and can lower the bounds on squarks and slepton masses to 1 TeV. Here we pointed out that the Higgs mass even with inclusion of radiative corrections can vary with electroweak symmetry breaking scale. We calculate it at two loop level and show that it varies substantially. We argue that Higgs mass like other coupling parameters can vary with energy scale and the Higgs potential with all orders loop corrections is scale invariant. This uncertainty to the Higgs mass calculation due to electroweak symmetry breaking around the supersymmetry breaking scale, normally taken as $\sqrt{m_{\tilde t_L} m_{\tilde t_R}}$, to minimize the 1-loop radiative corrections can be removed if one considers all significant radiative contributions to make Higgs potential renormalization group evolution scale invariant and evaluates electroweak symmetry breaking at the scale near the electroweak symmetry breaking scale. A large parameter space becomes allowed when one considers electroweak symmetry breaking at its true scale not only for producing correct values of the Higgs masses, but also for providing successful breaking of this symmetry in more parameter spaces.

hep-ph↗