Kinetics of nanoscale structure development during Mg-vapour reduction of tantalum oxide
R. Müller, M. Bobeth, H. Brumm, G. Gille, W. Pompe, J. Thomas
International Journal of Materials Research 98, 1138 (2007)
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 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 magnesia-tantalum structures as a base for producing highly nanoporous tantalum for capacitor applications.