Compositional and structural changes at the anodic surface of thermally poled soda-lime float glass

Applying high dc electric fields at elevated temperatures on silicate glasses results in displacement of ions, causing compositional and structural changes in the anodic surface. In this work, the ionic displacement was accompanied by electric current measurements during poling. The thickness of the Na(+) depletion layer calculated from the current curves agrees with the thickness measured by EDS only if displacement of Ca(2+) and O(-) are also taken into account. A depletion of Ca(2+), in the anodic surface has in fact been observed. Structural changes were confirmed by infrared diffuse and specular reflectance spectroscopies. A narrowing of the band at about 1070 cm(-1) can be attributed to an increase in the structural ordering degree. Refractive index measurements confirm compositional changes and contact angle measurements indicate the existence of a negative charge density at the anodic surface. (C) 2008 American Institute of Physics.