Browsing by Author "Sushmita Seth"

Now showing 1 - 2 of 2

A and B site engineered doping of the Bi2O3 to tune the structural and optical properties of lead-free BCZT ceramic
(Elsevier Ltd, 2024) Biplab Mondal; Sushmita Seth; Satyendra Prakash Pal
This work reports the different solid-state synthesis routes to tune between the A-site and B-site incorporation of the Bi2O3 additive element in the lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramic. The structural and optical properties of the synthesized samples were systematically investigated by utilizing XRD, FT-IR spectroscopy, Raman Spectroscopy, UV–visible, and Photoluminescence spectroscopy. The shifting of the XRD peaks towards higher angles and the decrement of the O–Ba–O bond length in the FT-IR spectra of the doped sample confirmed the A-site incorporation of the Bi3+ ion. Whereas, B-site substituted samples have shown the lower angle shifting of the XRD peaks and increased value of the O–Ti–O bond length in FT-IR spectra. The presence of co-existing multi-phases in all prepared ceramics structures were verified by the splitting of XRD peaks and Raman Spectroscopy data analysis. A significant decrement in the value of the energy band gap and higher emission intensity for the A-site doped sample was observed from the UV–visible and PL spectra respectively. These observations made from the optical properties indicate that the A-site substituted ceramics can greatly enhance the electrical and optical properties of the pure material concerning the B-site substituted ceramics. © 2023 Elsevier B.V.
Effect of different synthesis parameters on the structural, morphological and optical properties of hydrothermally synthesized tungsten diselenide (WSe2) nanostructures: Experimental and theoretical validation
(Elsevier Ltd, 2025) Sushmita Seth; Biplab Mondal; Monalisha Nayak; Satyendra Prakash Pal
In this study, tungsten diselenide (WSe2) nanostructures were synthesized via a hydrothermal route using sodium tungstate dihydrate (Na2WO4.2H2O) and selenium (Se) powder as precursors. Particular attention was given to the influence of synthesis parameters, namely reaction temperature and growth duration, as these play a decisive role in crystallite size, morphology, and the presence of impurities. To systematically evaluate their impact, WSe2 samples were prepared under different conditions and examined for structural, morphological, and optical variations. The as-synthesized samples were characterized by using X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray Analysis (EDAX), High Resolution Transmission Electron Microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Ultraviolet-Visible (UV-Vis) spectroscopy and Photoluminescence (PL) spectroscopy. The bonding structure and the vibrational modes of Raman spectrum were validated by Density Functional Theory (DFT) calculation using the B3LYP/LANL2DZ mode. The XRD and Raman spectroscopy measurements confirmed the formation of the hexagonal phase (2H-WSe2). The morphology transitioned from aggregated particles to flake-like nanostructures with increasing temperature, while reaction time influenced the crystal refinement and stacking. A significant decrement in the value of the energy band gap for most pure exfoliated WSe2 was observed from the UV-Vis absorption spectra. PL spectra revealed indirect and excitonic transitions with emission peaks in the near-IR region (∼1.3 and ∼1.5 eV). Further, the PL spectra of exfoliated bulk WSe2 exhibited a clear blue-shift of the emission peak, indicating effective material thinning from multilayered to few-layered WSe2. These optical properties indicate a possible optoelectronic potential of WSe2. © 2025 Elsevier Ltd