Faculty Publications

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Author: search.filters.author.Raghuvanshi, V.

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    Density and Refractive Index Variation of CaF2 Added Borosilicate Glasses
    (Springer, 2024) Raghuvanshi, V.; Shashikala, H.D.
    The borosilicate glass series with general formula 30SiO2-35B2O3-(35-X) Na2O-XCaF2 (X = 0, 10, 15, and 20 mol%) were prepared using the conventional melt-quenching technique. This paper focuses on the change in physical properties of borosilicate glass with an increase in CaF2 concentration. X-ray diffraction confirmed the amorphous nature of the prepared glass samples. Density was measured using Archimedes principle, and other physical parameters like molar volume and oxygen packing density were calculated with measured density. The density increased with an increase in the concentration of CaF2. The refractive index and UV-Vis spectroscopy of the glass samples were studied. Parameters like dielectric constant, molar refraction, reflection loss, electronic polarizability, metallization factor, and other UV parameters were also calculated using this data. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
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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 comprehensive study uncovering physical, structural, and optical properties of Cu2O and TiO2-reinforced borosilicate glasses as optical filters
    (Elsevier B.V., 2024) Raghuvanshi, V.; Rashmi, I.; Ingle, A.; Shashikala, H.D.; Nagaraja, H.S.
    In this study, the integration of transition metal oxides (TMOs), specifically Cu2O and TiO2, into a borosilicate glass matrix (30SiO2–35B2O3–35Na2O–5CaF2-X (TMO)) was investigated for enhanced glass functionality. Glass samples with varying TMO concentrations (X = 0, 1, 2, 3, 4 mol%) were prepared using the melt-quenching technique. X-ray diffraction confirmed the amorphous nature of the synthesized samples, while FTIR analysis showed structural changes, transitioning from trigonal BO3 to BO4 tetrahedra, alongside the formation of non-bridging oxygen species due to TMO integration. UV–Vis spectroscopy demonstrated a red shift in optical absorption profiles, correlating with a reduction in the indirect band gap as TMO content increased. Photoluminescence studies showed distinct behaviors, with Cu2O suppressing emission peaks and TiO2 exhibiting intriguing blue and green emissions, diminishing at higher concentrations. It was attributed that Cu2O had a larger impact on altering the glass network than TiO2. These findings contribute to understanding the properties of Cu2O and TiO2-containing borosilicate glasses, suggesting tailored optical properties for potential applications as bandpass filter and UV blocker. © 2024 Elsevier B.V.
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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 titanium redox states on luminescence and conductivity in TiO2 -doped borophosphate glass system
    (Elsevier B.V., 2025) Rashmi, R.; Ingle, A.; Raghuvanshi, V.; Shashikala, H.D.; Nagaraja, H.S.
    Borophosphate glasses have garnered significant interest due to their potential for optical and electronic applications. This research delves into the luminescent and conductive properties of 40P2O5–25B2O3-(35-x) BaO-xTiO2 (x = 0–5 mol%) glasses synthesized via the melt-quench method. The glass doped with 4 mol% TiO2 exhibited intense luminescence within the 400–600 nm spectrum, manifesting as a vivid blue emission and the highest Ti3+ ion concentration. Beyond this threshold, the luminescence intensity waned, highlighting the significance of Ti4+/Ti3+ ratios. Absorption spectra and X-ray photoelectron spectroscopy were utilized to study these multivalent ions. Temperature-dependent AC conductivity, exhibited a linear increase, consistent with the Correlated Barrier Hopping (CBH) model. Enhanced polaron hopping between Ti3+ and Ti4+ with increasing TiO2 content improved the dielectric constant and conductivity, peaking at 4.145×10?5 Scm?1 at 5 mol% TiO2 within the 450–530 °C range. These findings underscore the tunability of TiO2-doped glasses for optoelectronic applications. © 2024 Elsevier B.V.
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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.