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In this work, reduced graphene oxide-coated zinc borotellurite doped with erbium oxide nanoparticles denoted as ZBTEr (NPs)-rGO was studied as an approach to enhance the optical properties of glass materials. Herein, a melt-quenched technique was used to prepare the ZBTEr (NPs) glasses. A simple and inexpensive spray-coated technique was employed to deposit the rGO onto the glass surfaces directly. The morphological studies of ZBTEr (NPs)-rGO glass surfaces were investigated by scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HR-TEM) meanwhile, the structural investigation of ZBTEr (NPs) glasses was revealed by X-ray diffraction (XRD) and Raman analysis. The morphological analysis revealed the residual oxygen groups functionalized on ZBTEr (NPs)-rGO glass surfaces meanwhile, TEM images confirmed the presence of Er (NPs) in the glassy matrix. The glass samples showed the existence of structural disorder and amorphous nature. The absorption spectra presented the transition bands that existed from 4I15/2 ground state level to excited state levels of 2H9/2, 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I11/2, and 4I9/2, respectively. Judd–Ofelt analysis was performed to obtain the intensity parameters (Ωλ), radiative transition (A), branching ratios (βR), and radiative lifetimes (tr). The radiative parameter and branching ratio values suggested the higher stimulated emission radiative at 2H11/2 → 4I15/2 transition for present glass The luminescence spectra exhibited two emission peaks centred at 539 nm and 558 nm which were assigned to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions, respectively. The optical results for ZBTEr (NPs)-rGO and ZBTEr (NPs)-uncoated were compared to determine the differences between coated and uncoated glasses. These results highlight the significant effect of rGO deposited onto tellurite-based glass and thus, this work proposed the potential coating materials for improving current fiber optics. [ABSTRACT FROM AUTHOR]

Chromium (III) oxide (Cr2O3) nanoparticles are generated by thermal treatment (calcination) of precursor materials such as chromium nitrate along with a poly (vinyl pyrrolidone) capping agent. The samples produced were characterised by various techniques, including X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Examination results obtained from XRD showed that Cr2O3 nanoparticles exhibit hexagonal crystalline structures, with the presence of Cr and O in these novel materials being confirmed by results of analyses of both EDX and FT-IR. Results of TEM have pointed out that the average nanoparticle size was noticeably increased from 28 to 46 nm in relation to increase of calcination temperature of a range between 500 and 800 °C. The surface composition and valence state of the produced nanoparticles were examined by X-ray photoelectron spectroscopy (XPS), the optical energy gap has been evaluated using UV–visible reflectance spectra with the help of Kubelka–Munk equation. The energy band gap had a reversely proportional relationship with calcination temperature with a reduction in energy band gap from 3.12 to 3.01 eV. Photoluminescence (PL) spectra indicated an increase in photoluminescence with increasing particle size. The antibacterial activity of the Cr2O3 nanoparticles was evaluated in-vitro using gram-negative Escherichia coli ATCC 25922 and gram-positive Bacillus subtilis UPMC 1175. [ABSTRACT FROM AUTHOR]

In this paper, using heat treatment approach has achieved a successful synthesis of copper oxide (CuO) nanoparticles with monoclinic structure. Thus, copper(II) nitrate trihydrate has been employed as a metal precursor, polyvinylpyrrolidone as a capping agent, while the solvent was deionized water by altering the calcining temperatures from 500 to 800 °C. The XRD patterns, EDX and FTIR spectra have proved that the CuO nanoparticles obtained have a high level of purity, crystallinity and nano-size. The FESEM images showed that nanoparticles are spherical with a tendency of agglomeration while calcining temperature being increased. Additionally, it has been noted that as the calcining temperature rose, the average particles sizes increased as demonstrated by TEM images. The optical properties have been demonstrated by using the UV visible spectrophotometer; the obtained results have revealed that the energy band gab decreases in relation with the calcination temperature increment. Further results have shown that the photoluminescent intensity has been increased with the calcination temperature increment as demonstrated by photoluminescence. [ABSTRACT FROM AUTHOR]