Preparation of Tantalum Powders by the Reduction of Complex Oxyfluoride Compounds with Sodium

Abstract—The substances most suitable for use as oxygen-containing additives for the sodium-thermal fabrication of finely dispersed tantalum powder (K₂Ta₂O₃F₆, K₃TaOF₆, K₂TaOF₅, and KTaOF₄) are selected based on the thermodynamic and experimental investigations of reduction reactions of tantalum compounds with sodium from the melts containing complex oxyfluorides compounds. The application of the mentioned compounds gives the opportunity to fabricate tantalum powders with a specific surface area at a level of 3–5 m²/g, which is 8- to 10-fold higher than for the powders fabricated under the same conditions when reducing K₂TaF₇. It is shown that fabricated tantalum powders can be needed as the initial material for the development of the capacitor powder with a charge of 70 000–100 000 μFV/g.