Faculty Publications

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Author: search.filters.author.Raghuvanshi, V.Subject: search.filters.subject.Glass transition

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    Influence of V2O5 addition as a dopant and dispersed content in barium borophosphate glass on structural and optical properties
    (Elsevier Ltd, 2024) Rashmi, I.; Ingle, A.; Raghuvanshi, V.; Shashikala, H.D.; Nagaraja, H.S.
    The Barium Borophosphate glass system with molar compositions 40P2O5– 25B2O3-(35-x) BaO-xV2O5 and 40P2O5–25B2O3–35BaO-xV2O5 (x = 0,1,3,5 mol%) was synthesized using melt-quenching method. A comprehensive investigation of the structural and optical properties was conducted to compare the effects of V2O5 as a dopant and as an addition to the glass matrix. The physical parameters were assessed through the measurement of density. The influence of V2O5 introduction on vibrational modes was studied through Fourier-transform infrared (FTIR) and Raman spectroscopy. The UV–visible absorbance analysis unveiled the existence of multiple valence states of vanadium (V3+, V4+ and V5+). The reduction in bandgap was determined through the utilization of a Tauc plot, while the measurement of the refractive index allowed for the assessment of its variation with the composition of V2O5. Photoluminescence spectroscopy (PL) was employed to explore the presence of intrinsic defects within the glass matrix and the impact of V2O5 on the emission spectra. Furthermore, CIE chromaticity coordinates of synthesized samples were observed in both the white and blue regions, suggesting their potential application in display devices. Significantly, V2O5 glass doped with 1 mol% displayed chromaticity, characterized by CIE coordinates x = 0.288 and y = 0.386, closely matching the white region as well as the bandpass filter. The introduction of transition metal oxide dopants into borophosphate glass yielded exceptional emission properties. The ability to modify optical properties makes it more promising for these glass materials, particularly for applications like optical filters and displays. © 2024 Elsevier Ltd and Techna Group S.r.l.
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    A study on the influence of geometric coordination of cobalt ions on the structural, physical and optical properties of borosilicate glass
    (Elsevier Ltd, 2025) Raghuvanshi, V.; Rashmi, R.; Ingle, A.; Shashikala, H.D.; Nagaraja, H.S.
    This work explores the synthesis and characterization of cobalt oxide-added borosilicate glass using the melt-quenching technique. The glass system was investigated using various methods, including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), density measurements, UV–vis spectroscopy, photoluminescence, and electron paramagnetic resonance (EPR) spectroscopy. XRD validated the glass's amorphous nature, while FTIR results indicated significant bonding alterations, showing a transition from BO3 to BO4 units and from B3-O-Si to B4-O-Si linkages. The increased glass density further supported the formation of BO4 units. XPS analysis verified the presence of Co2+ and Co3+ ions within the glass matrix. Optical absorption studies revealed distinct electronic transitions for Co2+ ions in both tetrahedral and octahedral coordination, and for Co3+ ions in octahedral coordination, which was corroborated by EPR spectroscopy. The paramagnetic nature of Co2+ ions was analyzed, and the g-value was determined using X-band frequency. The study also noted the narrowing of the indirect band gap with the rise in the content of Co3O4, and the examination of the metallization criterion suggested a potential metallic nature for the synthesized glasses. Notably, the 0.05 mol% Co3O4-added sample exhibited a 48 % transmission rate and the highest emission, highlighting its potential as an optical bandpass filter. These findings underscore the versatility and tunability of cobalt oxide-added borosilicate glass for various optical technologies. © 2024 Elsevier Ltd and Techna Group S.r.l.
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    Influence of low concentrations of vanadium and titanium ions on the structural and optical properties of borophosphate glasses
    (Elsevier B.V., 2025) Rashmi, I.; Raghuvanshi, V.; Ingle, A.; Shashikala, H.D.; Nagaraja, H.S.
    A series of P2O5–B2O3–BaO glass system containing various V2O5 and TiO2 content (from 0.25 to 0.75 mol%) were synthesized using the melt-quenching method to examine their structural, EPR, and optical characteristics. EPR analysis confirmed VO2+ hyperfine splitting and the presence of Ti3+ ions in a tetragonally compressed octahedral structure. The local structures of VO2+ and Ti3+ centers were explored through spin Hamiltonian parameters (g??e) and optical transition energies. UV–visible spectroscopy revealed multiple oxidation states of vanadium (V3+, VO2+ and V5+) and titanium (Ti3+, Ti4+), which significantly influenced the optical characteristics. Photoluminescence (PL) studies indicated the presence of oxygen vacancies and intrinsic defects in the glass matrix, with [VO4]3- groups and Ti3+ ions significantly enhancing emission properties. The enhanced luminescence was observed for glasses with 0.75 mol% TiO2 and 0.75 mol% V2O5. Notably, the 0.75 mol% V2O5-doped glass, exhibited CIE chromaticity coordinates (x = 0.26, y = 0.31), closely aligning with standard white light. The tunability of optical properties through transition metal oxide doping highlights the potential of these glasses for advanced photonic applications, including optical filters and display technologies. © 2025 Elsevier B.V.