Wendeng Wang

Photocatalytic activity of a Bi-based oxychloride Bi4NbO8Cl

The Bi-based oxychloride Bi4NbO8Cl with a layered structure was studied as a novel efficient photocatalyst. The compound prepared by a solid state reaction method has a band gap of 2.38 eV. It possesses an excellent visible-light-response ability. The visible-light-driven photocatalytic activities for degrading methyl orange (MO) over different catalysts follow the decreasing order of Bi4NbO8Cl > Bi3O4Cl > anatase TiO2, different from the order found under UV light illumination (Bi3O4Cl > anatase TiO2 > Bi4NbO8Cl). The dispersion of Pt over Bi4NbO8Cl leads to an obvious increase in photocatalytic performance, to about 1.5 times higher. The polarizing fields in NbO6 and BiO8 local structures, as well as the internal electrical fields between [Bi2O2] and [Cl] slabs, are considered to be useful for the efficient separation of electron–hole pairs upon photoexcitation.

Anomalous thermal stability of Nd–Fe–Co–Al bulk metallic glass

The thermal stability of Nd60Fe20Co10Al10 bulk metallic glass (BMG) has been studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), isochronal dilatation and compression tests. The results show that the glass transition of the BMG takes place quite gradually between about 460 and 650 K at a heating rate of 0.17 K/s. Several transformation processes are observed during continuous heating with the first crystallization process beginning at about 460 K, while massive crystallization takes place near the solidus temperature of the alloy. The positive heat of mixing between the two major constituents, Nd and Fe, and, consequently, a highly inhomogeneous composition of the attained amorphous phase are responsible for the anomalous thermal stability in this system

High quality epitaxial Ge 1−x Sn x alloy films on Si with a Ge buffer by molecular beam epitaxy with combined sources

Epitaxial Ge<inf>1−x</inf>Sn<inf>x</inf> alloys were grown on Si(100) by MBE at low temperature with a Ge buffer layer. The Ge buffer was grown in the same system by two step method using GeH<inf>4</inf> as gas source.