Yttria stabilized zirconia (YSZ) thin films are obtained using both spray-pyrolysis and dip-coating. The ability of YSZ films incorporated with platinum nanospecies (Pt-YSZ) to detect oxygen is compared with that of pure YSZ thin films using a new experimental setup. With this system, the surface electrical resistance of the films as a function the oxygen content is measured at a fixed temperature. In addition, the effects of thermal annealing on the oxygen sensitivity of the films are observed. Platinum doped samples, Pt-YSZ, show different kinetics of carrier diffusion as compared to pure YSZ samples.
We first focus on the kinetics of nanoparticle growth in a microemulsion synthesis of CdSe semiconductor nanocrystals. The process consists of a fast initial stage of typical time constant of the order of 103 s followed by a slow stage of time constant of the order of 104s. Growth proceeds similarly to that described for the hot-matrix synthesis of CdSe, underlining the generality of the two-stage growth mechanism, irrespective of the matrix type and synthesis conditions. However, the time constant of each stage in the microemulsion synthesis is much larger than in the hot-matrix one. Also, the ratio between the fast and slow time constant is appreciably bigger. We also prove that larger size reverse micelles, obtained by increasing the water:surfactant ratio, generally lead to larger CdSe nanoparticles. Bis(trimethylsilyl) selenium is the crucial precursor for the CdSe nanoparticle synthesis. An intermediate stage of the chemical reaction limiting the bis(trimethylsilyl) selenium production is described theoretically. [...]
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