Dry field-assisted ion exchange of silver in amorphous and crystalline systems
The insertion of silver in different alkali-conducting systems by dry field-assisted ion exchange was investigated in the present work. Silver ions are introduced from a metal electrode in close contact with the alkali conductor by applying a DC electric potential at about 400°C. Ag migrates into the material from the positive electrode in order to substitute the alkaline species moving toward the negative pole.
It is shown that penetration depths as high as 150 µm can be obtained in just 5 min using a current density of 20 mA mm-2. Both amorphous (soda lime silicate glass) and partially crystalline ceramics (stoneware, glass-ceramic) are investigated . It is found that in all the systems the penetration depth of silver depends linearly on the treating time and current density; in other words, it is proportional to the amount of charge per unit of surface displaced under the effect of the external field.
The obtained materials present several fascinating characteristics like improved mechanical properties (due to the formation of surface compressive stresses), antimicrobial properties (due to the presence of silver) and bright luminescence.