Repositorio Institucional de CIMAV (Centro de Investigación en Materiales Avanzados)
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Growth and structure of tin dioxide thin films obtained by an improved spray pyrohydrolysis technique
Get PDFUndoped and doped tin dioxide thin films have been prepared by an improved method of spray pyrohydrolytic decomposition of SnCI4-5H20 onto a glass substrate. We show that, with this overhead hot-plate and counter flux spray, the gravitational force plays an important role in distinguishing droplets with a radius greater than 26 μm. X-ray diffraction spectra show that the structure is polycrystalline, with a grain size in the range 24-100 nm and a preferred orientation that is thickness dependent. It is shown by observations of the film microstructure by transmission electron microscopy that there is first an amorphous layer with embedded crystallites over which many crystals grow. This microstructure suggests that the films start to grow in an amorphous manner, then film growth continues with the nucleation of many small crystallites and finally some of them grow until a closely packed microstructure of crystallites is formed. Scanning electron microscopy of film surfaces indicates that surface roughness could be responsible for the large decrease in optical transmission of some films. Rutherford backscattering spectroscopy shows that film stoichiometry is close to the SnO2 phase and no significant chlorine contamination is present in the films
Corrrelations for some saturated thermodynamic and transport properties of refrigerant.
No full textCorrelations obtained by linear regression, (least squares), are presented for the saturation temperature Ts(P), saturation pressure Ps(T), vaporization enthalpy Hfa(T), vaporization specific volume Vfg(T), density of saturated vapour pg(T), saturated liquid dynamic viscocity Mf(T), saturated vapour dynamic viscocity Ma(T) and the thermal conductivity of a saturated liquid Kf(T), covering the complete temperature range given in the data source, (ASHRAE Fundamentals SI)
