%0 Conference Paper
%K Electrochromic devices
%K Optical proterties
%K Proton conductor
%K Tantalum oxide
%A Nilgün Özer
%A Carl M Lampert
%B 8th International Workshop on Glasses and Ceramics From Gels
%C Faro, Portugal
%D 1995
%G eng
%T Structural and Optical Properties of Sol-Gel Deposited Proton Conducting Ta<sub>2</sub>O<sub>5</sub> Films
%1 <p>Windows and Daylighting Group</p>
%2 LBL-37800
%8 09/1995
%X <p>Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC<sub>2</sub>H<sub>5</sub>)<sub>5</sub> as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 °C, were amorphous. Films heat treated at higher temperatures were crystalline Ta<sub>2</sub>O<sub>5</sub>. The solar transmission values (Ts) of tantala films on glass generally range from 0.8-0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at λ=550 nm increased from n=1.78 to 1.97 with increasing heat treatment from 150 to 450 °C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=1 x 10<sup>-3</sup> in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta<sub>2</sub>O<sub>5</sub> films revealed that these films have protonic conductivity of 3.2 x 10<sup>-6</sup> S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.</p>