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Tungsten oxide films of thicknesses 1095 nm have been cathodically deposited onto ITO coated glass substrates kept at room temperature, at a rate of 13 nm/min. The electrolyte solution has been prepared by adding 0.025 M tungsten (dissolved in 30% H2O2) to 0.25 M H2SO4. XRD observations showed that all films are amorphous. The film resistivity at room temperature was found to be 9 × 106 Ω cm, and from the resistivity–temperature dependence, the thermal activation energy was obtained as 0.29 eV. The refractive index, n, and the extinction coefficient, k, have been computed from the corrected transmittance and reflectance over the spectral range 400 to 800 nm. Absorption versus photon energy curves give an indirect transition with optical energy gap of 3.25 and 3.36 eV for the as‐deposited and coloured states, respectively. The electrochromic properties of the prepared films have been investigated in situ and both solar transmittance and optical density have been evaluated in the coloured and bleached states. The electrochemical coloration and bleaching were performed in an electrolyte of 0.4 M H2SO4 solution. The coloration efficiency has been evaluated as 50 cm2/C at λ = 600 nm, which is comparable with the results obtained from films prepared by other methods.

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Tungsten oxide films of 240–1080 nm thickness were deposited on indium tin oxide (ITO) coated glass substrates using an electrochemical deposition technique. All films were amorphous, as proved by X-ray diffraction (XRD), and had an electrical resistivity of 106 Ω·cm and spectral transmittance exceeding 75% in the visible region. The electrochromic (EC) properties were measured in situ during colouration and bleaching cycles. The EC parameters, T sol b, T sol c, ΔT sol and Δ(OD)sol and the solar colouration efficiency ηsol were evaluated at different preparation and performance parameters. The results showed that at small film thickness, the solar colouration efficiency changes linearly and tends toward saturation at larger thickness. At colouration potentials ≥2 V, the solar colouration efficiency is almost constant whereas the active sites are transformed to colour centres. In contrast, the efficiency has an exponential dependence on electrolyte concentration. The optimum values are: film thickness = 1080 nm, colouration potential - 2 V and electrolyte concentration = 0.4 M. The corresponding EC parameters are: ΔT sol =0.458, Δ(OD)sol=0.632 and ηsol=34 cm2/C.

Clear poly(methyl-methacrylate)-PMMAdosimeter is widely used in food irradiations. Positron annihilation lifetime spectroscopy (PALS) is one of the unique tools used for studying free-volumes and openvolume type defects in solid media. The Vicker's microhardness measurements offer a simple and nondestructive tool for investigating the mechanical behavior of polymer materials. PALS as well as microhardness measurements were carried out for PMMA samples, irradiated with lowand high-linear energy transfers (LET). The low-LET irradiations were provided at lethal doses of gamma radiations for vegetative bacteria. Such irradiations showed a chain scission in the PMMA samples. High-LET irradiations showed behavior different from the low-LET ones.The observed behavior depends on the alpha particle fluence. The microhardness testing was carried out for virgin and irradiated PMMA samples at high-LET. A negative correlation was found between PALS measurements and microhardness results. The optical characteristics and structural studies for the virgin and irradiated PMMA samples were in agreement with the PALS and microhardness measurements.