Effect of Oxygen Flow Rate on the Particle Size Distribution and Morphology of the Ultrafine Rhenium Powders Prepared by CVD
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Ultrafine rhenium (Re) powders were prepared by a chemical vapor deposition method at different oxygen flow rates. Results show that the particle size ranges between 100 nm and 1300 nm and that the size distributions are close to the normal distribution. The d-values (d10, d50, and d90) of the ultrafine Re powders initially decrease and then increase with increasing oxygen flow rate from 20 to 80 mL/min. The morphology of the ultrafine Re powders is irregular polyhedron, and these powders grow through either coagulation or continuous deposition. In addition, the amount of residuals after the experiment reduces with the increase of oxygen flow rate from 20 to 40 mL/min. Above 40 mL/min, no appreciable residuals could be observed. X-ray diffraction analysis of the residuals indicates that the samples were low valence Re oxides of ReO3 and ReO2.
The work was supported by the National Natural Science Foundation of China (51874363, U1760202), Natural Science Foundation of Hunan Province (2019JJ40345), and Hunan Scientific Technology projects (2018RS3022, 2018WK2051).
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