Luminescence of Eu ion in alumina prepared by plasma electrolytic oxidation

Eu ion luminescence in aluminium oxide nanocrystals and layers prepared by plasma electrolytic oxidation (PEO) are investigated in this study. The Eu ion in PEO coatings has intense luminescence allowing such material to be used for preparation of various phosphor materials. In this study, Eu ion doped coatings were prepared with two methods: anodization and pulsed bipolar plasma electrolytic oxidation. Also, for comparative studies, alumina nanocrystals with the same amount of Eu ions were prepared using Sol Gel and molten salts methods. Obtained Eu-doped coatings were studied using luminescence methods. Typical Eu ion luminescence bands were observed, however intensity and spectral distribution differs drastically depending on preparation method and parameters used, therefore the Eu ion luminescence could be used as coating quality luminescent probe. Additionally, the possibility to incorporate the Eu ions in trivalent or divalent state exhibiting bright red and blue luminescence accordingly was demonstrated by using different oxidation parameters. Moreover, comparison measurements between powder samples and coatings were made.