Search

Monodisperse mesoporous silica microspheres (MSM-SF) were successfully prepared through PICA and pseudomorphic transformation using silica fume as original silica source. The structure and morphology of spheres were quantitatively investigated by Zata potential and particle size analyzer, N2 sorption isotherms, XRD, SEM and TEM. The results showed that the monodisperse spherical mesoporous silica microspheres (MSM-SF) exhibited uniform spherical morphology, worm-like mesoporous, large BET surface area of 559.9m2/g; its BJH average pore size diameter and total pore volume are 3.3nm and 0.12cm3/g, respectively. This preparation method provides a new synthetic strategy to control the particle morphology and structure simultaneously, meanwhile this method can also significantly reduce the cost of synthesis of mesoporous silica microspheres.

HfSiN/Cu/HfSiN/SiO2/Si multilayer films were prepared on Si substrate via magnetron sputtering technology. Annealing experiments of samples among 400°C and 700°C were carried out in order to investigate the anti-diffusion performance of HfSiN thin film to Cu. XRD, AFM and FPP were used to characterize the structure, morphology and the resistivity of the thin films before and after annealing, respectively. The failure temperature and failure mechanism of HfSiN thin film were analyzed. The anti-diffusion failure temperature of HfSiN thin film is 600 °C. And the main reason is that a large number of Cu large particles passed through HfSiN diffusion barrier layer and reacted with Si substrate and oxygen to generate Cu3Si and CuO with high resistance.

The anodic current-potential behaviors of PS fabrication by doubled-cell electrochemical etching method have been studied. There are three reaction regions: porous silicon formation region, a transition region and electropolishing region in I-V curves. Polishing current and the HF acid concentration has a directly proportional relationship, the electropolishing current of silicon increased with the increase of the concentration of HF, in a certain concentration range. The electropolishing current of silicon increased with increasing the sweep rate on the condition of the same HF concentration.

The UF resin/SiO2 composites microspheres with particle size of 2μm were successfully prepared by polymerization of silica sol from base-catalyzed hydrolysis of tetraethyl orthosilicate, and urea-formaldehyde via the PICA approach, and then calcination in air to remove organic UF resin and yield porous silica microspheres. The samples were characterized by Zetasizer NanoZS Instrument, SEM and Nitrogen adsorption-desorption isotherms. The results showed that the synthesized porous silica microspheres with a BET surface area of 67.01m2/g, a BJH average pore size diameter of 37.32 nm and a total pore volume of 0.69cm3/g, respectively.

The effect of HF concentration on the surface structure of porous silicon (PS) was carefully investigated by the AFM characterization. The results showed that no pores were present on PS surface which was prepared under the higher concentration of HF (10%). However, the pores were gradually visible with the HF concentration reduction. The main pores diameter was about 100 nm, when the concentration is 5.71%. The data of surface roughness and the main height distribution of the “hill” both showed an increase with the reduction of concentration, from 6.39 nm increase to 16.9 nm and from 30 nm increase to 90 nm, respectively, which implied that the pores were better exposed under the lower HF concentration.