Effect of water on permittivity of nanodielectrics exposed to the atmosphere

Relative dielectric constant and dissipation factor (tan¿) values as a function of frequency have been measured for a variety of water types. The effect of water absorption on the permittivity properties of crystalline powders or nanopowders when exposed to various humidity levels is also examined. Powdered materials were characterized by XRD and were consisting of calcite (CaCO
₃
), anatase, rutile (TiO
₂
), ¿- and ¿-alumina (Al
₂
O
₃
). The induced polarization changes in the materials by the applied dehydration process, i.e. either high vacuum of 10
^-4
Pa (10
^-6
mbar) drying, or calcination in air at temperatures of up to 600°C, were investigated. The advantage offered by vacuum dehydration is that nano-dielectrics maintain their particle size and crystal integrity.