Physico-chemical aspects of sol-gel thin film deposition: Control of film porosity
- Sandia National Labs., Albuquerque, NM (United States)
- Sandia National Labs., Albuquerque, NM (United States); and others
During sol-gel thin film deposition, polymeric or particulate sols are deposited on a substrate by dip or spin-coating. Sols are rapidly concentrated by evaporation, leading to aggregation and physical or chemical gelation. At the final stage of drying the gel is further compacted by the capillary pressure arising from the creation of liquid-vapor menisci at the terminus of liquid-filled pore channels. This paper examines the role of the molecular- and intermediate-range structure of inorganic sols (e.g. size, fractal dimension, degree of cyclization), surface chemistry, and deposition conditions on the microstructure (pore volume, pore size, and surface area) of the corresponding dried films. We establish synthesis and processing protocols to create quite dense films useful for protective, electronic, and optical applications as well as films with controlled pore sizes and pore volume fractions useful for sensors and membranes. Under certain conditions where condensation reactions accompanying film deposition are largely avoided, we find drying shrinkage to be reversible resulting in highly porous aerogel films.
- OSTI ID:
- 126644
- Report Number(s):
- CONF-950402--
- Country of Publication:
- United States
- Language:
- English
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