Kinetics of nanoscale structure development during Mg-vapour reduction of tantalum oxide

Abstract

Electron microscopic observations revealed the development of a complex interpenetrating morphology of magnesia and tantalum after magnesium-vapour reduction of tantalum oxide powder. In the early reaction stage, a nanoscale lamellar and rod-like morphology is found. This rather regular structure decomposes and coarsens during further annealing. By leaching of magnesia, nanoporous tantalum with large inner surface area is obtained. A possible growth mechanism for the observed initial cellular structure is proposed. A theoretical analysis aims at finding the optimum process parameters in order to prepare and to stabilise especially fine magnesiatantalum structures as a base for producing highly nanoporous tantalum for capacitor applications.

Features of the Formation of the Reaction Mass and Structure of Metal Powders During the Reduction of Complex Oxide Compounds of Refractory Metals of v and Vi Groups by Vapors of Alkaline Earth Metals

“…Это объясняется специфическим механизмом образования частицы металла в процессе восстановления. Исследования, выполненные авторами работы [3], показали, что частица оксида тантала после восстановления парами магния характеризуется полосчатой структурой, представленной перемежающимися пластинчатыми частицами оксида магния и металлического тантала. Между ними имеется свободное пространство (зазор), размеры которого позволяют атомам магния или кальция проникать вглубь частицы к фронту реакции.…”

Extraction of Tantalum Powder via the Magnesium Reduction of Tantalum Pentoxide

“…However, multiple oxides, such as MgTa 2 O 6 and Mg 4 Ta 2 O 9 , have been employed as raw materials to produce nanosized tantalum powder [15,16]. Scrap recycling, the flux effect, and so on have been studied with fixed reduction temperatures [8,17,18]. In this study, we investigated the reduction behavior from pure tantalum oxide to tantalum powder via magnesium gas with various reduction temperatures and studied the characterizations of product powders, such as the phase evaluation and microstructure.…”

Effect of Magnesium Reduction Process on Oxygen Content of Pickling Niobium Powder

“…However, there are few studies on magnesium reduction to reduce the oxygen content of niobium powder [11][12][13][14][15]. After oxygen reduction, the oxygen content of niobium powder is still on the high side, and the complete degree of oxygen binding with magnesium in the process of magnesium reduction and the degree of secondary oxidation on the surface of niobium powder in the process of cooling will affect the oxygen content of niobium [15][16][17][18][19][20][21][22].…”