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The morphology evolution from monoclinic molybdenum trioxide (β-MoO3) to orthorhombic molybdenum trioxide (α-MoO3) and quantitative analyses of their mixtures were examined. It was found that the morphology (from spherical to elliptical shape) and color (from green to white) displayed obvious changes when β-MoO3 converted to α-MoO3 in ambient air at 773 K. The transformation from β-MoO3 to α-MoO3 resulted from a change of the internal crystalline structure. The mass percent of β-MoO3 in MoO3 mixtures showed an excellent linear relationship with the relative intensity ratio of the strongest peaks in X-ray diffraction patterns. This approach provides a simple and time-saving method to evaluate the amount of β-MoO3, which is a promising material in catalyst and electrochemical applications, in such mixtures. This finding may provide guidance for the analysis of catalytic performance of MoO3 mixtures. In addition, it was found that β-MoO3 can be easily decomposed into suboxides such as MoO2 and Mo4O11 in pure argon gas atmosphere. The possible decomposition mechanism of β-MoO3 is discussed.

In the work, the reaction kinetic and mechanism of the reduction of WO2 to W by CO or CO-CO2 mixed gas were investigated in the range of 1351–1430 K. Various technologies such as XRD, FE-SEM, TG, thermodynamic calculation, and model fitting methods were adopted to analyze the experimental data. The results showed that the reduction of WO2 to W was a one-step reaction process without any intermediate products generated. The higher the temperature was, the faster the reduction rate. The reduction processes of WO2 to W by CO or CO-CO2 mixed gas was controlled by the interfacial chemical reactions with the activation energies extracted being 113 kJ/mol and 90 kJ/mol, respectively. Combining the phase transition and morphology evolution characterizations, a possible reaction mechanism for the reduction of WO2 to W was proposed. [ABSTRACT FROM AUTHOR]

The classical DLS (Dynamic Light Scattering) experiment uses a digital correlator to calculate the ACF(Auto-Correlation Function) and deduces the information of the particle size. Although the commercial digital correlators are readily available and with a higher speed, it usually costs twice that of a Counting Board and on the other hand, the calculating speed is not the point but the accuracy of measurement in the DLS system. In this paper, a new DLS particle sizing method using a Counting Board (M9003) has been developed based on 'labVIEW', which reduces the cost of the system dramatically. The pulses from the PMT are counted by a Counting Board at a given sample time. Then, the power spectrum is calculated and the particle size deduced using a characteristic decay constant. The method is systematically tested using small polystyrene latex particles with a wide range of particle concentrations as well as different diameters in suspension. [ABSTRACT FROM AUTHOR]