Raghuvanshi, V.Rashmi, R.Ingle, A.Shashikala, H.D.Nagaraja, H.S.2026-02-032025Ceramics International, 2025, 51, 2, pp. 1661-16732728842https://doi.org/10.1016/j.ceramint.2024.11.142https://idr.nitk.ac.in/handle/123456789/20525This 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 BO<inf>3</inf> to BO<inf>4</inf> units and from B<inf>3</inf>-O-Si to B<inf>4</inf>-O-Si linkages. The increased glass density further supported the formation of BO<inf>4</inf> 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 Co<inf>3</inf>O<inf>4</inf>, and the examination of the metallization criterion suggested a potential metallic nature for the synthesized glasses. Notably, the 0.05 mol% Co<inf>3</inf>O<inf>4</inf>-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.Borosilicate glassDensity (optical)Electron density measurementElectron spin resonance spectroscopyFourier transform infrared spectroscopyGlass bondingGlass transitionOptical transitionsParamagnetic resonancePhotoluminescence spectroscopyCobalt oxidesElectron paramagnetic resonance spectroscopyFourier transform infraredOctahedral coordinationOptical-PropertyTransition-metal oxidesX- ray diffractionsX-ray photoelectronsX ray photoelectron spectroscopy