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Suppression of Field Crystallization of Anodic Niobia by Oxygen

2006; Institute of Physics; Volume: 153; Issue: 5 Linguagem: Inglês

10.1149/1.2184909

1945-7111

H. Habazaki, T. Ogasawara, H. Konno, Ken‐ichi Shimizu, Shigekazu Nagata, K. Asami, K. Takayama, P. Skeldon, G.E. Thompson,

Concrete Corrosion and Durability

Solid-solution films containing up to 50 atom % oxygen, prepared by magnetron sputtering, were used to investigate the influence of the oxygen on field crystallization during anodizing at in ammonium pentaborate electrolyte at . The findings reveal that field crystallization is hindered dramatically by addition of 20 atom % oxygen to the substrate, while no crystallization occurs for a atom % O substrate. Prior thermal treatment accelerates field crystallization of niobium, but not the atom % O substrate. The thermal treatment is considered to promote generation of precursor sites for crystal nucleation. However, sufficient oxygen in the substrate may restrict precursor development and/or reduce the compressive stresses in the amorphous anodic niobia that can facilitate crystal growth.