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Lu J.-M.,Beijing Institute of Technology | Cheng X.,Xiamen University | Cheng X.,Fujian Key Laboratory of Advanced Materials
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica | Year: 2016

The electrochemical responses of heavily doped n-type single-crystal silicon (CSi) during the formation of porous silicon (PSi) layers in hydrofluoric acid-based electrolytes were investigated. A series of PSi layers were fabricated by constantly applying different anodic current densities, which were selected according to the linear polarization curve. The surface and cross-sectional morphologies of the PSi layers were studied by scanning electron microscopy. The electrochemical behavior of CSi and PSi electrodes was compared by linear sweep polarization and chronopotentiometry techniques. The important parameters associated with the electrochemical reactions at the electrodes were evaluated by analyzing the Tafel plots and chronopotentiograms obtained before and after the PSi formation. Structural models of the CSi electrode/electrolyte and PSi electrode/ electrolyte interfaces were suggested based on the experimental data. Accordingly, the interfacial characteristics of CSi and PSi electrodes were discussed. © Editorial office of Acta Physico-Chimica Sinica. Source

Yang L.,Xiamen University | Yang L.,Fujian Key Laboratory of Advanced Materials | Zhang Y.,Xiamen University | Zhang Y.,Fujian Key Laboratory of Advanced Materials | And 2 more authors.
Progress in Chemistry | Year: 2016

Polymer derived silicoboron carbonitride (SiBCN) ceramics possess such excellent properties as high temperature stability, oxidation resistance, creep resistance and special electrical properties. They have been fabricated as ceramic fibers, composites, porous ceramics, coatings, microdevices, and become alternative materials for potential applications in the fields of aerospace, energy, microelectronics. In recent years, researchers have made great progresses in developing new methods of precursor synthesis. The characterizations in microstructures and high temperature properties of SiBCN ceramics have been carried out. Possible applications in high temperature sensors, oxygen resistance coatings of carbon nanotubes/carbon nanofibers (CNTs/CNFs), and sintering additives have also been sought. The preparation routes of polymer derived SiBCN ceramics (including synthesis, pyrolysis and processing of precursors), the microstructures, basic properties and high temperature properties of SiBCN ceramics are reviewed. Accordingly, major problems are summarized and future research trends are highlighted. © 2016, Editorial Office of Progress in Chemistry. All right reserved. Source

Shao Z.,Xiamen University | Zhang Y.,Xiamen University | Zhang Y.,Fujian Key Laboratory of Advanced Materials | Cheng X.,Xiamen University | Cheng X.,Fujian Key Laboratory of Advanced Materials
Progress in Chemistry | Year: 2014

As a three-dimensional nanoporous material with low density and high porosity, silica aerogel exhibits a low thermal conductivity at room temperature and becomes an ideal nanoporous super thermal insulating material. However, the poor mechanic property and fragment occurred during ambient pressure drying have greatly limited the practical applications of silica aerogel. The apparent enhancements in integrity, strength and flexibility are achieved with the new-type of silica aerogels prepared by compositing or crosslinking, which makes it possible to be applied alone in the form of monolith as thermal insulating materials. In this paper, the porous structures, basic properties and thermal insulation principles of silica aerogels are briefly introduced. The research progress of newly developed fiber reinforced composite silica aerogels, polymer crosslinked silica aerogels, and the other combined silica aerogels as monolithic thermal insulation materials are focused. Finally, the key problems in the field of silica aerogels are summarized and the future research trends are highlighted. Source

Wu Y.,Xiamen University | Zhou Z.,Xiamen University | Zhou Z.,Fujian Key Laboratory of Advanced Materials | Tuo Y.,Xiamen University | And 3 more authors.
Materials Letters | Year: 2013

Self-assembled BiOI microrings composed of nanoplatelets have been successfully fabricated via a simple hydrothermal method using an oleic acid contained solvent as a reaction medium. For a comparison, only BiOI microplatelets were obtained without oleic acid. Oleic acid acts critically as a trigger for the assembly of microrings through an interaction between carboxylate anion and Bi3+ ion (3COO--Bi3+). The complex (3COO--Bi3+) adsorbed onto the planes of BiOI nuclei, controlling the orientated crystal growth, and the microrings formed through a self-assembly of nanoplatelets. The photocatalytic activity of the obtained BiOI microrings was found to be about 30% higher than that of microplatelets. The novel way may also be extended to preparation of a wide range of self-assembled microrings composed of nanoplatelets. © 2013 Elsevier B.V. Source

Huang M.,Xiamen University | Wang K.,Xiamen University | Huang Y.,Xiamen University | Huang Y.,Fujian Key Laboratory of Advanced Materials | And 3 more authors.
Materials Science Forum | Year: 2016

The exploration of efficient preparation methods of VO2(M) powders, especially the controls of particle sizes, is a challenge. In this article VO2(M) powders were prepared by a liquid phase precipitation and post annealing method. The structure and morphology of the VO2(M) powders were characterized by XRD and SEM. The effects of annealing temperature and the amounts of additive SiO2 aerogels on the particle size controlling were studied.The thermal phase transition properties were characterized by DSC analysis. The results reveal that the transformation of crystal phases from V6O13 to VO2(M) takes place in the annealing process and the additive of SiO2 aerogels can control the particle size and promote the particle size to be smaller effectively. © 2016 Trans Tech Publications, Switzerland. Source

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