Synthesis of nanocrystalline molybdenum powder by hydrogen reduction of industrial grade MoO3

• Industrial grade MoO3 powder was used to prepare ultrafine Mo powder by reducing MoO3 vapor with hydrogen at 1323 K.
• Pure ultrafine metal Mo powder can be synthesized by adjusting flow rates of carrier gas Ar and reduction gas H2.
• The single crystalline platelet-shaped MoO2 was found to be formed as an intermediate product.

In the present work, ultrafine metal Mo powder with a high purity was successfully prepared by one step direct reduction of MoO3 vapor with H2 at 1323 K. MoO3 vapor was generated by the evaporation of industrial grade MoO3, which is much cheaper than pure MoO3. It is found that increasing H2 concentration is beneficial for the reduction of MoO3 to metal Mo, as well as for the decrease of particle size of Mo particles. The results obtained at a low H2 concentration show that the mixture of hexagonal platelet-shaped MoO2 single crystalline and Mo polycrystalline can be obtained. The present method provides a simple approach to prepare nanocrystalline Mo powder.