Sputtered silver-based low-emissivity coatings with high moisture durability

Moisture durability of low-emissivity (low-E) coatings with an oxide/silver/oxide/glass system was investigated. Aluminum-doped zinc oxide (AZO) films from a target of 95Zn-5Al (at%) and silver-palladium films from targets of 99.7Ag-0.3Pd, 99.5Ag-0.5Pd and 99Ag-1Pd (at %) were used as oxide layers and a silver layer, respectively. A tin silicon oxide (TSO) film from a target of 50Sn-50Si (at%) was introduced as a cover layer. The structure information, surface morphology and palladium concentration of the coatings were obtained from X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and inductive-coupled plasma spectroscopy (ICP), respectively. Mechanical durability of the coatings was evaluated by using a scratch tester. After the coatings were exposed to 90% relative humidity at 40 degreesC for weeks, white-dot defects larger than 0.2 mm in diameter were counted. It was found that, in the TSO/AZO/Ag-Pd/AZO/glass system, the palladium addition to the silver layer remarkably reduced the moisture-induced white-dot defect deterioration, and the TSO cover layer contributed to stabilizing the optical properties and improving the scratch resistance. (C) 2000 Elsevier Science Ltd. All rights reserved.