Determination of physical characterization of tungsten oxides

Abstract

The physical characterization of surface area, micropore volume, micropore size distribution, mesopore volume, average pore diameter and fractal dimensions of four tungsten oxides of ammonium tungsten bronze, (NH 4) 0.5WO 3 (ATB), hydrogen tungsten bronze, H 0.33WO 3 (HTB), violet tungsten oxide, W 18O 49 (TVO), and tungsten blue oxide, WO 3+WO 2.9 (TBO) were evaluated from the analysis of nitrogen adsorption–desorption isotherm data. Analysis of the adsorption–desorption isotherm data suggested that in this study TVO with the largest mesopore volume, the smallest micropore volume, the narrowest micropore size distribution, the lowest fractal dimension value and the biggest average pore diameter was advantageous for hydrogen reduction during fine tungsten powder production process and disadvantageous for doping process; HTB with the largest micropore volume, the widest micropore size distribution, the highest fractal dimension value and the smallest average pore diameter was favorable for doping process, and characterization properties of ATB and TBO in this investigation were just between TVO's and HTB's. Results showed that it was a preferable method to investigate the physical characterization of oxides by using adsorption–desorption isotherms in this study and the physical characterization of tungsten oxides should be taken into account before they are used in reduction process or in doping process.