الفهرس 
CHAPTER 1 : chromogenic materialsOnly 14 pages are availabe for public view
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Abstract
Prussian blue films have been electrochemically deposited using a solution of potassium ferrocyanide and Iron(III) chloride . Tin-doped indium oxide (ITO) coated glass was used as a cathode when the anode was a platinum layer . The films underwent insertion/extraction of electrochemical ions using potassium chloride.
In order to optimise the preparation conditions, a series of Prussian blue films have been electrochemically deposited using different solution concentrations. The transmittance and reflectance were measured in the wavelength range from 350-850 nm using a double beam spectrophotometer device (JASCO-V-670).
The results showed that:
- It is obvious that the spectral transmittance for samples prepared at solution concentrations of (0.04 and 0.05) mol. possess a quite high values of transmittance in the bleached state and the values of the spectral transmittance at 550 nm are (63.3%, 62.9%) , respectively.
- However, samples prepared at higher solution concentrations (0.08 and 0.1)mol, have quite low values of spectral transmittance, T(λ) at 550 nm are (34.4 and 28.7%), respectively.
- In contrast, the transmittance values after colouration for all samples are quite low. Also, There is no appreciable change in spectral reflectance with wavelength in both bleached and coloured states and it has an average values less than 10% for all of the samples.
- The sample in the coloured state possess quite high values of absorption. For example at a wavelength of 550 nm, the values of absorption for a sample prepared at a solution concentration of 0.04 mol are (0.32, 0.70) in the bleached and coloured states, respectively. This means that PB films can be classified as “absorption modulated films”.
- It is obvious that samples prepared at concentrations of (0.04 and 0.05) mol exhibit a good electrochromic behaviour, where the difference in ΔTv is ( 0.32 ) in both cases. Comparing with samples prepared at concentrations of (0.08 and 0.1)mol ΔTv = (0.18 and 0.05), respectively.
- Samples prepared at concentrations of (0.04 and 0.05) mol possess higher values of optical density (0.28). Films prepared at higher concentrations possess a lower values of optical density (e. g. for a sample prepared a concentration of 0.08 mol has an optical density of (0.23).
- The dependence of the contrast ratio on wavelength for samples of (0.04 and 0.05) mol, It was clear that the maximum transmittance change and highest CR value occurs at 700 nm.
-Colouration potential of ±1.5V was found to be the optimum optimum potential used for bleaching and colouring samples. Electrolyte concentration (1M KCl) is the best concentration used during the injection/extraction process.
-In order to optimise the electrochromic properties (EC) of the prepared Prussian blue samples. The effect of deposition time on the (EC) properties have been studied.
The results showed that:
-It is obvious that the spectral transmittance for samples prepared at deposition time of 10 min at concentration (0.04 and 0.05) mol. Possesses quite high values of transmittance in the bleached state and the values of the spectral transmittance at 550 nm are (52.95%, 61.21%) respectively.
-However, samples prepared at higher deposition time 30 min at concentration (0.04 and 0.05) mol have quite low values of transmittance, T(λ) at 550 nm are (43.11,21.72%), respectively.
- In contrast, the transmittance values after colouration for all samples are quite low. Also, There is no appreciable change in spectral reflectance with wavelength in both bleached and coloured states and it has an average values less than 10% for all of the samples.
- It is clear that the sample in the coloured state possesses quite high values of absorption. For example at a wavelength of 550 nm for sample T1 the values of absorption are ( 0.39, 0.76) in the bleached and coloured states, respectively. And for sample T4 the values of absorption are ( 0.29, 0.70) in the bleached and coloured states, respectively. This means that PB films can be classified as “absorption modulated films”.
- It is obvious that sample which prepared at solution concentration 0.04 exhibit a good electrochromic behaviour at a deposition time 20 min where the difference in ΔTv is (0.32), but sample which prepared at solution concentration 0.05 exhibit a very good electrochromic behaviour at a deposition time 10 min where the difference in ΔTv is (0.38). Comparing with samples prepared at a deposition time of 30 min for samples which have a solution concentration 0.04 and 0.05 are ( ΔTv = 0.23 and 0.09), respectively.
-At a solution concentration (0.04 and 0.05) mol it is clear that samples prepared at a deposition time of 10 min possesses a higher values of optical density (0.56 and 0.39). Films prepared at higher deposition time possess a lower values of optical density (e. g. for a sample prepared at a deposition time 30 has an optical density of (0.27 and 0.19), respectively.
- The maximum transmittance change and highest contrast ratio (CR) value occurs at 700 nm.
-X-ray study showed that films are amorphous state and scanning electron microscopy indicated that a good electrochromic properties. It can be observed that the film has a small grain diameter (43nm) and some large grains, A good electrochromic behavior can be achieved with films which have a small grain size, i.e, large grain boundaries
-The cycling voltametry (CV ) show a symmetrical redox pair for samples prepared at 0.04 and 0.05 solution concentration.