An Investigation of Structures of Thermal and Anodic Tantalum Oxide Films

Abstract

Tantalum oxide films produced from anodic oxidation and thermal oxidation at 400 and 800°C have been investigated with respect to long- and short-range structure by X-ray diffraction and X-ray absorption spectroscopy, respectively. Films formed at 800°C show orthorhombic structure with greater disorder compared to the powder reference, where six O atoms were observed at an average radial distances of powder) and Å (800°C Ta oxide film). Lower temperature films consist primarily of metastable and appear to be relatively stable for extended times of treatment with a first shell not unlike that of based on a linear combination analysis. Furthermore, using a linear combination of and α-Ta metal, the amorphous anodic oxide films studied as a function of thickness were observed to exhibit a relatively ordered local structure consistent with the high-temperature (i.e., 800°C) phase. This work demonstrates that the nanoscale oxide films formed on tantalum exhibit an ordered local structure, reflecting the very compact nature that enhances its corrosion resistance. © 2005 The Electrochemical Society. All rights reserved.