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Interface Stoichiometry and Structure in Anodic Niobium Pentoxide

Published online by Cambridge University Press:  16 September 2008

Matthew J. Olszta  and
Elizabeth C. Dickey
Matthew J. Olszta
Affiliation:
Department of Materials Science and Engineering, Center for Dielectric Studies, and The Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA
Elizabeth C. Dickey*
Affiliation:
Department of Materials Science and Engineering, Center for Dielectric Studies, and The Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA
*
Corresponding author. E-mail: ecd10@psu.edu
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Abstract

High-resolution transmission electron microscopy and electron energy loss spectroscopy (EELS) were performed on electrochemically anodized niobium and niobium oxide. Sintered anodes of Nb and NbO powders were anodized in 0.1 wt% H3PO4 at 10, 20, and 65 V to form surface Nb2O5 layers with an average anodization constant of 3.6 ± 0.2 nm/V. The anode/dielectric interfaces were continuous and the dielectric layers were amorphous except for occurrences of plate-like, orthorhombic pentoxide crystallites in both anodes formed at 65 V. Using EELS stoichiometry quantification and relative chemical shifts of the Nb M4,5 ionization edge, a suboxide transition layer at the amorphous pentoxide interface on the order of 5 nm was detected in the Nb anodes, whereas no interfacial suboxide layers were detected in the NbO anodes.

Keywords

electrolytic capacitorniobiumniobium oxideamorphous oxidedielectricHRTEMEELS
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 14 , Issue 5 , October 2008 , pp. 451 - 458
Copyright
Copyright © Microscopy Society of America 2008

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