Galvanoluminescence of oxide films during the anodization of titanium

• Anodization of titanium in 10 g/L Na3PO4∙12H2O water solution
• Galvanoluminescence (GL) is related to the existence of flaws in oxide coating.
• GL shows wide bands in the visible and near infrared spectral region.
• GL is more intense for higher current density and higher electrolyte temperature.
• GL intensity might be an indicator of the roughness of titanium surface.

In this paper, we have presented the results of our investigation of galvanoluminescence (GL) originating from oxide films obtained by anodization of titanium in alkaline solutions. For the first time we have measured weak GL during the anodization of titanium and found strong influence of sample's surface pretreatment, as well as anodizing conditions (current density and electrolyte temperature). GL is more intense for rougher titanium samples, higher current density, and higher temperature of electrolyte. Spectral characterization of GL showed that there are wide GL bands present mostly in the visible and near infrared spectral region. As the potential of anodization approaches the breakdown voltage, a numerous transient sparks appear superimposed on the GL.