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Silicon nanoparticles (Si-NPs) obtained by electrochemical etching of silicon wafer were incorporated into various dielectric matrices using solÀgel method. To attain a wide range of dielectric constant and band gap energy, three matrices are selected (SiO 2 , ZrO 2 and TiO 2 ) and the Si-NPs were incorporated in these matrices at different concentrations. Structural studies by transmission electron microscopy and Raman spectroscopy confirm the presence of Si-NPs in the matrices. Moreover, the significant compressive stress induced by the matrix is observed. Photoluminescence (PL) studies show that Si-NPs preserve their luminescent properties in SiO 2 matrix and ZrO 2 matrix but not in TiO 2 matrix. The PL peak position depends not only on the dimension of Si-NPs but also depends on their concentrations. This is due to the coupling effect between the nanoparticles which increases with concentration.

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The utilization of waste as raw materials in the production of functional materials is a growing area of interest to promote global sustainable growth. This work studied the microstructure, chemical properties, and phosphorus (P) dissolution efficiency of carbon/hydroxyapatite (HAP) nanocomposites derived from fish scale wastes, namely FSBCs. Tilapia scales were pyrolyzed at different temperatures (450–600 °C) and the dissolution performance of the biochars in acidic media was evaluated. The pyrolysis of fish scales yielded biochars which are carbon/HAP nanocomposites of which the characteristics, including the specific surface area, carbon content, degree of crystallinity of HAP, and the degree of CO32− substitution in HAP crystals, were dependent on the pyrolysis temperature and had an influence on the dissolution efficiency. P dissolution experiments suggested that the specific surface area and the presence of carbon in the composite played an important role during the dissolution process. The presence of the organic residues on the carbon could potentially block the calcium sites on HAP from citric acid and lower the dissolution efficiency. The ratio of CO32−/PO43− substitution in HAP also affected the dissolubility of FSBCs. The manipulation of their surface area and the CO32−/PO43− ratio of these materials would allow us to increase its solubility, which could benefit a prospective application such as P fertilizer production.

Bismuth ferrite (BiFeO 3 ) was synthesized using hydrothermal method in two different size autoclaves (100-and 200-mL capacities). By fixing conditions including filling factor, quantity of precursors, KOH concentration, reaction temperature, and duration time, the properties of the resulting products were compared. In this work, different analytical techniques were applied to identify the phase evolution and morphology of the samples such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). The results demonstrated that the crystalline phases and the particle sizes were different when the dimension of the autoclave was greatly changed. Considering the reaction temperature and the autoclave size, we suggested that the heat transfer from the autoclave into the solution might be delayed and it may be the reason why the Bi25FeO40 phase was mainly obtained when the samples were prepared at 160°C for 6 h in the 200-mL autoclave.