Abstract—
The pore structure of powders prepared via magnesium vapor reduction of Nb2O5 and Mg4Nb2O9 in the range 540–680°C has been studied in detail. The results demonstrate that lowering the reduction temperature slows down diffusion processes, which allows coarsening of the primary structure of the reduced oxide particles to be prevented, thereby increasing the volume and surface of pores less than 5 nm in diameter. Reducing Nb2O5 at a temperature of 680°C, we have obtained niobium powder with a specific surface area of 83.4 m2/g. As the reduction temperature is lowered further, the pore size decreases to the extent that most pores become filled with native Nb2O5 oxide and the specific surface area decreases. In the case of Mg4Nb2O9 reduction under such conditions, the pore size is such that the powder obtained upon leaching of magnesium oxide is in effect an amorphous Nb2O5 oxide.
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Orlov, V.M., Kiselev, E.N. Magnesium Vapor Reduction of Niobium Oxide Compounds in the Range 540–680°C. Inorg Mater 58, 1266–1273 (2022). https://doi.org/10.1134/S0020168522120081
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DOI: https://doi.org/10.1134/S0020168522120081