Influence of graphene nanopowder impurities on the structural and optical properties of sodium borate copper-based glass: Towards UV/NIR shielding materials

Graphene nanopowder was used as an unconventional additive to the studied oxide glasses, where it was added to the raw components of the copper-sodium borate glass by weight% according to the chemical formula: [(B₂O₃)_0.6mol%(Na₂O)_0.3mol%(Cu₂O₃)_0.2mol%]+(Graphene)_x, where x = 0, 0.2, 0.4, 0.6 and 1 g. Then, the traditional melt quenching method was considered for the glass preparation process. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Ultraviolet–Visible spectra UV–Vis, and the electron spin resonance (ESR) were used for the characterization processes. According to the XRD patterns, the prepared samples have been divided into two categories, pure glassy samples (x < 0.6 g), and glass-ceramic samples (x ≥ 0.6 g). The FTIR showed the presence of the structural groups BO₃ and BO₄ as well C[dbnd]O. Also, FTIR showed a conversion from BO₃ to BO₄ when the content of graphene increased, which means a decrease in the number of nonbridging oxygen atoms NBOs. The deconvolution parameters showed an increase in the relative area of the band assigned to the OH and CH₂ groups. According to ESR spectral analysis, Cu²⁺ ions should occupy octahedral sites with tetragonal distortion as the ground state, where the effective g values and the peak-to-peak width were computed and linked with the structural variation of the prepared samples. The UV–Vis optical measurements showed that the as-prepared glasses/glass-ceramics could act as an optical pass filter in the region of the visible light, as well as good candidates for UV- and NIR shielding applications.