Thermal treatments, cell

Optimum conditions for the formation of CdS by the acidic method on metallic A1 substrate at 25 °C have been reported as follows pH 2.3, potential -1 V vs. SCE, and electrolysis time > 2 h [44]. Thermal treatment improved the characteristics of the films and their photovoltaic properties, which were evaluated by evaporating a CU2S layer on the CdS/Al film, to form a heterojunction cell. The influence of the deposition substrate on the formation and morphology of CdS was found to be important. The aluminum substrates gave the best results among Pt, Mo, and Al. In the case of molybdenum, surface blocking by adsorbed sulfur was considered. 

Simple electroless techniques have been used for the formation of CdTe layers following an anodic or a cathodic route of deposition. For instance, spontaneous cathodic formation of CdTe was observed on Ti or glass electrodes short circuited with a corroding A1 contact (electron source) in a solution of Cd " " and HTe02 ions [96]. After thermal treatment and subsequent growth of an a-Pb02 layer on them, the as-obtained CdTe thin films were found to exhibit n-type behavior in alkaline polysulfide PEC cells. 

FT-IR spectra were recorded at RT on a Perkin-Elmer 1760-X spectrophotometer equipped with a cryodetector, at a resolution of 2 cm-" (number of scans -100). In the 1070-960 cm- region, band integration and curve fitting were carried out by Curve fit, in Spectra Calc. (Galactic Industries Co.). Powdered materials were pelleted in self-supporting discs of 25-50 mg cm-2 and 0.1-0.2 mm thick, placed in an IR cell allowing thermal treatments in vacuo or in a controlled atmosphere. 

Figure 9.8. Influence of cell density on DeNOx at 10 ppm ammonia slip. Extruded V205/ W03—Ti02 catalysts with ( , ) 3%, and (A, A) 1.9% V205. ( , A)400cpsi, and ( , A) 300cpsi. Thermal treatment at 550°C for 50 h.

The most satisfactory nonpressure process is known as thermal treatment. The wood to be treated is immersed in a preservative at an elevated temperature. This causes the air in the wood cells to expand so that when the wood is transferred into a preservative bath of lower temperature, the air contracts forming a partial vacuum and atmospheric pressure forces the liquid into the wood. 

For the FTIR measurements (Bruker IFS28 resolution 2 cm-1 MCT detector), the samples, pressed into self-supporting pellets, were placed into a quartz IR cell equipped with KBr windows attached to a vacuum line (residual pressure 1 x 10 6 Torr). Thermal treatments were carried out in situ. To decrease the scattering of the IR beam, severely affecting the transparency of the samples in the in the 4000-3000 cm-1 range, a system of condenser mirrors were placed between the IR cell and the detector. 

The advantage of simplicity is illustrated in the design reported by Pettiti et al. (1999) this was assembled mostly with commercial parts. The cell allowed thermal treatments at temperatures up to 823 K, in either a reducing or oxidizing atmosphere, and it could be used in transmission and fluorescence modes of detection. The body of the cell was a stainless steel six-way cross. One flange of the cross carried the heater and the opposite flange the sample holder. The heater was a simple design of Ni—Cr wire wrapped around a silica cylinder. The sample holder was... 

---