Nanocomposites and nanomaterials

The sensitivity to moisture peculiarities of nanoscale tin dioxide films obtained by means of polymers 
Chebanenko A.P., Filevska L.M., Grinevych V.S., Smyntyna V.A. 
Odessa Mechnikov National University, Dvoryanska str., 2, Odessa-65082, Ukraine. E-mail: lfilevska@gmail.com

Tin dioxide, having a high chemical resistance and stability of adsorption characteristics, is widely used as a material for sensitive elements of gas sensors. It is the nanoscale forms of SnO2 that show the most gas sensitivity, as a result of the high variability of conductivity. On the other hand, the large relative surface of such forms leads to the active adsorption of water. Taking into account the need to create gas sensors operating without additional heating, the study of the moisture influence on the electrical properties of tin dioxide at room temperature would be useful. 
In the presented work, the kinetics features of the sensitivity to moisture at room temperature of nanosized tin dioxide films obtained using polymers are investigated.
Thin nanoscale films of tin dioxide were obtained by a sol-gel method using polyvinyl acetate for structuring. Tin bis(acetylacetonato)dichlorotin(IV) was used as a precursor for the preparation of SnO2 layers.
Studies of electric current relaxation in layers of tin dioxide at room temperatures with alternate inlet of water vapor and dry air showed a reversible exponential nature of the current changes, and hence the adsorption-desorption processes.
The character of the adsorption time constant dependence on the applied voltage indicates an increase of adsorption rate processes with voltage and subsequent stabilization of the adsorption process. The time constants of adsorption and desorption ratio shows a higher rate of desorption processes, which witnesses in favor of the associative nature of the adsorption of water on the films under study at room temperature.
The results indicate that SnO2 films may be used as sensitive elements for moisture sensors operating at room temperature.