The wafer bonding process has many applications in the fabrication of microelectronic, optoelectronic, power and microinachined devices. In this article fusion bonding of silicon, wafers and study of their interface are reported for the first time in Iran. Also, the bonding of two silicon wafers, with one (or both) of the wafers having a thermally grown silicon dioxide layer, has been performed and tested.

TiO2/SiO2 and V2O5/ TiO2/SiO2 nano photocatalyst have been synthesized by sol-gel method. X-ray diffraction, SEM, FT-IR, and UV-VIS methods were used to characterize the structures and properties of these photo catalysts. The particle size was determined to be 7 nm using the Scheerer,s equation. The results of XRD and FT-IR confirmed the existence of V2O5, TiO2 and SiO2. In order to investigate and compare the photocatalytic activity of TiO2/SiO2 and V2O5/TiO2/SiO2, photodegradation of monochlorobenzene and dichlorobenzene in water under the ultraviolet and visible lights was studied. The decrease in concentration of monochlorobenzene and dichlorobenzene was monitored by UV-vis spectroscopy. Our results show that in the visible light, the V2O5/ TiO2/SiO2 have better photocatalytic activity in comparison with the TiO2/SiO2.

Structural properties and chemical composition change the photocatalytic activity in TiO2-SiO2 nanopowder composite. The SiO2-TiO2 nanostructure is synthesized based on sol-gel method.The nanoparticles are characterized by x-ray fluorescents (XRF), xray diffraction (XRD), tunneling electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), UV-vis.Spectrophotometer and furrier transmission create infrared absorption (FTIR) techniques. The rate constant k for the degradation of methylen blue in its aqueous solution under UV irradiation is determined as a measure of photocatalytic activity.Dependence between photocatalytic activity and SiO2 content in the composite is determined. Rate constant k is found dependent on the content of SiO2 in the composite that calcined at 900oC. The addition of low composition SiO2 to the TiO2 matrix (lower than 45%) enhances the photocatalytic activity due to thermal stability and increasing in the surface area. The effects of chemical compositions on the surface topography and the crystallization of phases are studied.

Fe3O4 nanoparticles (NPs) with a continuous and mesoporous silica (m-SiO2) shell were synthesized using a one-step method, sourcing silica from rice husk ash (RHA). The rice husk was thermally treated to obtain ash, from which silica was extracted as sodium silicate and precipitated by pH reduction. This silica powder, combined with iron chloride salts, facilitated the synthesis of the core-shell NPs. Mint extract acted as a capping agent to prevent agglomeration, and CTAB (cetyltrimethylammonium bromide) was used to create the porous SiO2 shell. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) characterization investigated the structure, size, and shell formation. Coating integrity and suspension stability were assessed through Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). DLS analysis showed a relatively narrow particle size distribution with an average hydrodynamic size of 72.6 nm. Small-angle X-ray scattering (SAXS) provided insights into the meso- and nanoscale structure, while BET and nitrogen adsorption-desorption isotherms confirmed the mesoporous nature of the silica shell. Magnetization measurements showed superparamagnetic behavior, with specific magnetization values of 57.9 emu/g for Fe3O4 and 27.5 emu/g for Fe3O4@m-SiO2. These results confirm the successful synthesis of superparamagnetic magnetite NPs with a mesoporous silica coating from RHA.

In this study, at first, reduced graphene oxide (RGO) has been synthesized by Hummers’,method and then RGO/SiO2 binary compound and finally RGO/SiO2/Fe3O4 ternary compound were synthesized by co-precipitation method. Magnetic properties of nanoparticles were investigated by VSM and their morphology was studied by SEM. Crystalline structure and functional groups and bonds analyzed by XRD and FTIR, respectively. The size of nanoparticles of iron-oxide, reduced graphene oxide/silicon dioxide, and iron-oxide/reduced graphene oxide/ silicon-dioxide was respectively estimated as 11. 9, 10. 44, and 11. 17 nm. Saturation magnetization of iron-oxide and ternary nanocomposite are obtained as 72 emu/g and 31. 2 emu/g respectively that shows that by covering iron-oxide nanoparticles with nonmagnetic materials, the obtained saturation magnetization decreases. Photocatalytic activity of the synthesized RGO/SiO2/Fe3O4 was evaluated in the degradation of methyl orange dye (MO) as a pollutant under irradiation of ultraviolet light. Photocatalytic efficiency 51. 59% was obtained. RGO/SiO2/Fe3O4 composite with capable of photocatalytic activity with efficiency of 51. 59 %, was evaluated as a pollutant in the degradation of methyl orange (MO).

A critical research area overlooked in previous studies on nano-silica material is the understanding of how its physical characteristics influence its final behavior as a composite when added to the asphalt binder. This study aimed to understand the feasibility of modifying the nanosilica with asphalt binder based on the asphalt binder characteristics. 60/70 penetration grade asphalt cement was prepared by adding (2%, 4% and 6%) of nanosilica by weight of asphalt. Properties of nanosilica material and asphalt cement were first examined. To prepare the modified asphalt binder was heated at 140C, blended by mechanical mixer at a speed of 2000 rpm for different mixing durations (30 to 60) minute. The modified asphalt binder was examined for rheological properties including penetration grade, softening point temperature, penetration index, Brookfield rotational viscosity and ductility test. Results shows that the modified asphalt binder stiffness increases based on rheological properties and sensitivity of temperature decreases with increasing nanosilica percentage. A­4 % nano silica by asphalt weight enhanced the conventional properties of the modified asphalt binder and became proper in hot weather conditions. While ductility of modified asphalt decreases with increasing nano silica percentage, due to stiffness and agglomeration increased. Finally, longer mixing time to more than 60 min had an adverse effect on the ductility property and lead to agglomeration of nanosilica modified asphalt binder.