Results of studies on the effect of inorganic overlayers on the long-term stability of discontinuous silver films deposited on softened poly(2-vinylpyridine) (PVP) substrates are reported in this paper. Discontinuous silver films were evaporated onto PVP-coated glass substrates held at 425 K in a vacuum of 8 × 10-6 Torr. The films were coated with overlayers of Al2O3, SiO2 and ZrO2 prior to exposure to the atmosphere. The stability of the films against exposure to the atmosphere was studied by monitoring the resistance during and after exposure to the atmosphere. The stability was monitored for a period of 120 days and the film's resistance had stabilized by 30 days. Results indicate that overlayers improve the stability considerably and SiO2 seems to be the best passivator, closely followed by ZrO2. However, compared to Al2O3, ZrO2 gives better protection even with a smaller overlayer thickness. A stable discontinuous film with a gauge factor of about 30 could be prepared by depositing silver onto softened PVP passivated by an overlayer, after 30 days of ageing.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films