Mingxu Zhang

Electronic Structure and Visible-Light Absorption of Transition Metals (TM=Cr, Mn, Fe, Co) and Zn-Codoped SrTiO3: a First-Principles Study*

First-principles calculations are performed on the influence of transition metal (TM=Cr, Mn, Fe, Co) as codopants on the electronic structure and visible-light absorption of Zn-doped SrTiO 3. The calculated results show that (Zn,Mn)-codoped SrTiO 3 requires the smallest formation energy in four codoping systems. The structures of the codoped systems display obvious lattice distortion, inducing a phase transition from cubic to rhombohedral after codoping. Some impurity Cr, Mn and Co 3d states appear below the bottom of conduction band and some Fe 3d states are located above the top of valence band, which leads to a significant narrowing of band gap after transition metal codoping. The enhancement of visible-light absorption are observed in transition metals (TM=Cr, Mn, Fe, Co) and Zn codoped SrTiO 3 systems. The prediction calculations suggested that the (Zn,Mn)- and (Zn,Co)-codoped SrTiO 3 could be the desirable visible-light photocatalysts.

Synthesis of super plasticizer NF-30 from coal coking by product washing oil and performance analysis

Super plasticizer was synthesized by using coal coking by product washing oil and industrial naphthalene. The results show that sulfonationt time (2.5 h), sulfonation temperature (160 °C) and condensation time (5.0 h) are key factors. Adding oxidizing agent MO in the course of synthesis can decrease the emission of SO2 in exhaust (20%). Compared with NF, NF-30 have some advantages in lower cost, high water reducing rate (19.7%) and optimum early strengths. Moreover, TGA-DTA and SEM analysis were adopted to research the NF-30 modified concrete on hydyation mechanism. The analysis show that, compared with NF, there are a large number of hydration products such as Ca (OH)2, C-S-H, AFt etc of NF-30, the structure of NF-30 is dense and the performance is good.