Formation of self-organized niobium porous oxide on niobium

Abstract

Anodization of niobium in mixed H 2SO 4/HF electrolytes was investigated. Under optimized electrochemical conditions the formation of self-organized porous Nb 2O 5 layers was observed. The porous Nb 2O 5 layers consist of ordered pore arrays with single pore diameters ranging from 20 to 30 nm. The pore morphology and the layer thickness strongly depend on the HF concentration and the time of anodization. Well-ordered uniform porous layers of up to 500 nm in thickness were formed. The formation of thicker layers is hampered by dissolution process and a tendency to film delamination. © 2004 Elsevier B.V. All rights reserved.