An insight into the process and mechanism of a mechanically activated reaction for synthesizing AlH3 nano-composites

The reaction pathway as well as the mechanism of the solid state reaction between MgH2 and AlCl3 has been a mystery so far. Based on SEM, TEM and NMR (Nuclear Magnetic Resonance) analyses, an amorphous intermediate (AlH6)n was preferentially formed and recrystallized as a γ phase at the final stage of the reaction. As a novel finding, this research provides a deep insight into the process and mechanism of this mechanically activated reaction.

Reaction kinetics for the solid state synthesis of the AlH3/MgCl2 nano-composite by mechanical milling

The process of mechanical milling has been proved to be a cost-effective way to synthesize the AlH3/MgCl2 nano-composite by using MgH2 and AlCl3 as reagents. However, so far there is no comprehensive knowledge of the kinetics of this process. In an effort to predict the reaction progress and optimize the milling parameters, the kinetics of the synthesis of the AlH3/MgCl2 nano-composite by mechanical milling of MgH2 and AlCl3 is experimentally investigated in the present work. The reaction progress or the transformation fraction upon milling for different times is evaluated using the isothermal hydrogen desorption test of the as-milled samples at 220 °C, which is much lower than the threshold temperature for the de-hydriding of the reagent MgH2 but enough for the de-hydriding of the as-synthesized nano-sized AlH3. The effects of milling parameters on the reaction kinetics as well as the underlying mechanism are discussed by referring to the mechanical energy input intensity, the vial temperature and the Gibbs free energy change for the reaction. Furthermore, it is found that the Johnson-Mehl-Avrami (JMA) model can well describe the kinetics theoretically. By fitting the experimental data with the JMA expression, the theoretical kinetics expressions, the equation parameters, and the activation energy are obtained.

Atomic structure of defects and interfaces in TiO2-B and Ca:TiO2-B (CaTi5O11) films grown on SrTiO3

An atomic-scale analysis of the interfacial structure and defects in CaTi₅O₁₁grown on SrTiO₃and TiO₂-B grown on CaTi₅O₁₁is presented.

Pyrite nanotube array films as an efficient photocatalyst for degradation of methylene blue and phenol

The nanotube topography would improve the optical property of the pyrite crystals. The photodegradation of MB and phenol suggested that the pyrite nanotubes array films would be potential to be used in the treatment of pollutants.