The migration of Cl− and I− ions in anodic alumina
1995; Elsevier BV; Volume: 37; Issue: 9 Linguagem: Inglês
10.1016/0010-938x(95)00059-s
ISSN1879-0496
AutoresM. Skeldon, K. Shimizu, P. Skeldon, G.E. Thompson, G. C. Wood,
Tópico(s)Ferroelectric and Piezoelectric Materials
ResumoThe migration of Cl− and I− ions in barrier-type anodic films has been studied during galvanostatic anodizing of aluminium at high faradaic efficiency. The ions were incorporated into films either directly, by ion-implantation, or by growth of films on ion-implanted aluminium substrates. Control experiments, using ion-implanted xenon, reveal that ionic transport in the amorphous anodic alumina is not significantly affected by the implanted doses. Cl− and I− ions migrate inwards more slowly than O2−OH− ions, under the electric field during film growth; the migration rates relative to that of O2−OH− ions are about 0.72 and 0.29, respectively, with the former value being an upper limit. Within the limitations of the measurements the relative migration rates are not significantly dependent upon the anodic current density, or alternatively the electric field, suggesting that ionic migration involves a co-operative transport process. Modified behaviour is observed at comparatively high implanted doses, of about 5 × 1019 ions m−2, which includes transient pitting and apparent migration of iodine species outwards.
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