Nb powders were synthesized by magnesio-thermic reduction. Nb2O5 is reduced by Mg via an oxygen-metal cation exchange in a mixed powder bed. Although thermodynamics favor reduction of Nb2O5 with Mg, the final phase distributions can be affected by the Mg content and interaction between products and reactants. Mg/Nb2O5 molar ratio was changed from 5 to 7.5 in order to evaluate the reaction pathway and relevant phases. Due to premature Mg depletion, samples with Mg/Nb2O5=5 resulted in intermediate Mg-Nb-O oxides according to the phase equilibria. A time-series comparison of Mg/Nb2O5=5 at 700 °C and 800 °C resulted in faster Mg-Nb-O intermediate phase formation at higher temperatures. Depending on the average oxidation state, the face-centered cubic Mg-Nb-O and hexagonal Mg3Nb6O11 phase were identified.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering