The present work demonstrates the microwave-assisted synthesis of two different structural morphologies containing nickel oxide nanoparticles (NiO NPs) embedded in nitrogen (N) and sulfur (S) co-doped reduced graphene oxide (NS-rGO) nanosheets. The synthesized NiO anchored on NS-rGO nanosheets (NS-rGO-NiO composites) and NiO covered by NS-rGO nanosheets (NS-rGO:NiO composites) were used as an application in electromagnetic interference (EMI) shielding effectiveness (SE). The EMI SE studies reveal that NS-rGO:NiO composites show improved performance as compared to NS-rGO-NiO composites. In NS-rGO:NiO composites, the covered surface of NiO NPs by conducting NS-rGO nanosheets helps to improve the EMI SE application. The synthesized composite materials were extensively characterized using various techniques including scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. Binding energy of N/S element in rGO nanosheets were analyzed by XPS and it is confirmed that the N atoms were present in three states in carbon skeleton of NS-rGO nanosheets as pyridinic, pyrrolic, and graphitic states; however, S atoms were present in single state as C–S–C configuration. The as synthesized NS-rGO:NiO composites reveal good performance for EMI applications and demonstrate the SE value of more than ∼21 dB at thickness of 1.1 mm film of NS-rGO:NiO composites in microwave X-band range (8.2–12.4 GHz).

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Recycling has been pointed out as an alternative to the disposal of waste materials in industrial landfills. In the present study, the transformation of residues (discarded foundry sand - DFS, grits, and lime mud) in glass-ceramic materials is shown. The glasses were obtained by the melting/cooling method. The precursor materials, glasses, and glass-ceramics were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), and differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA). The glassy materials were milled, pelleted, and thermally treated at the crystallization temperatures given by DSC data to obtain the glass-ceramics (885, 961, and 1090 ºC). The main formed phases were cristobalite, α-wollastonite (parawollastonite), and β-wollastonite (pseudowollastonite). The glass-ceramics showed very low water absorption and apparent porosity (0.26 to 0.88 wt% and 0.66 to 1.77 vol%, respectively). The results confirmed that the studied residues can be used as raw materials for the manufacture of vitreous and glass-ceramic materials.

Manganese oxides were synthesized during 40 min at 140 ºC via Microwave-Assisted Hydrothermal (MAH) method and treated at different temperatures in order to evaluate the phase evolution using structure refinement (Rietveld method). The samples obtained were heat treated at temperatures defined by means of thermal analysis (160 ºC, 480 ºC, 715 ºC, 870 ºC, 920 ºC and 1150 ºC) and analyzed by X-Ray Diffractometry (XRD), X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectroscopy, Raman scattering, UV-Vis absorption and Scanning Electron Microscopy (SEM). Structural characterizations allowed to identify five distinct phases:

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