The Influence of SiO2 + SiC + Al (H2PO4)3 Coating on Mechanical and Dielectric Properties for SiCf/MWCNTS/AlPO4 Composites

SiC fiber-reinforced AlPO₄ matrix (SiC_f/MWCNTs/AlPO₄) composites were fabricated using a hot laminating process with multi-walled carbon nanotubes (MWCNTs) as the absorber. A coating prepared from SiO₂ + SiC + Al (H₂PO₄)₃ was applied to the surface of the SiC_f/MWCNTs/AlPO₄ composites prior to an anti-oxidation test at 1273 K in air for 40 h. The anti-oxidation effect was verified by a three-point bending test, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and a dielectric property test. Anti-oxidation mechanism investigations revealed that the coating effectiveness could be attributed to three substances, i.e., SiO₂, SiP₂O_7, and SiO₂ + AlPO₄ solid solution from the reactions of SiC + O₂→SiO₂ + CO, SiO₂ + P₂O₅→SiP₂O₇ and SiO₂ + AlPO₄→solid solution, respectively.     

Electronic,Structural, and Optical Properties of Mono-Doped and Co-Doped (210) TiO2 Brookite Surfaces for Application in Dye-Sensitized Solar Cells—A First Principles Study

Titanium dioxide (TiO₂) polymorphs have recently gained a lot of attention in dye-sensitized solar cells (DSSCs). The brookite polymorph, among other TiO₂ polymorphs, is now becoming the focus of research in DSSC applications, despite the difficulties in obtaining it as a pure phase experimentally. The current theoretical study used different nonmetals (C, S and N) and (C-S, C-N and S-N) as dopants and co-dopants, respectively, to investigate the effects of mono-doping and co-doping on the electronic, structural, and optical structure properties of (210) TiO₂ brookite surfaces, which is the most exposed surface of brookite. The results show that due to the narrowing of the band gap and the presence of impurity levels in the band gap, all mono-doped and co-doped TiO₂ brookite (210) surfaces exhibit some redshift. In particular, the C-doped, and C-N co-doped TiO₂ brookite (210) surfaces exhibit better absorption in the visible region of the electromagnetic spectrum in comparison to the pure, S-doped, N-doped, C-S co-doped and N-S co-doped TiO₂ brookite (210) surfaces.