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Understanding ammonia oxidation over metal oxide surfaces is crucial for improving its detection with resistive type gas sensors. Formation of NO

Tin dioxide whiskers have been grown from SnO vapor in a tube furnace in a flowing mixture of argon and oxygen at a constant source temperature, and the effect of the oxygen concentration in the carrier gas on the morphology, structure, and phase composition of the whiskers was studied. Single-crystal SnO2 whiskers can only be obtained in a narrow range of oxygen concentrations. Tin dioxide whiskers doped with different concentration of antimony (0–0.25 at.%) have been grown from SnO and Sb2O3 mixtures in a tube furnace in a flowing mixture of argon and oxygen at a constant source temperature. The whiskers are about 100 μm in length and well crystallized. They possess a high structural perfection. The influence of Sb on crystal structure, morphology, optical properties of the SnO2 whiskers is discussed. The electrophysical properties and sensitivity of individual whisker towards NO2 and CO have been investigated.

A complementary gas sensor and gas chromatography/mass spectrometry study was performed to investigate the chemical basis of acetone vapor sensing via semiconductor metal oxide gas sensors. The effect of additives to nanocrystalline SnO2-based sensor materials was analyzed. The main process that contributes to the electrical yield of this interaction and thus to the sensor response is a complete acetone oxidation to CO2and H2O. At the same time it is clearly shown that this sensor response is severely limited by the rate of desorption of the reaction products. The main contributors to this negative influence on the sensor response are heavy organic compounds with molar masses larger than that of acetone. It is also shown that their negative effect could be mitigated by the incorporation of catalytic clusters of gold on the surface of SnO2based sensor materials. This kind of catalyst acts either as a preventor of the formation of heavy and complex organic molecules on the sensor surface or as a combustion catalyst, which facilitates their decomposition.

The effect of Pd nanoparticles on the H2 sensitivity of SnO2 thin films was studied in real working conditions using X-ray Absorption Spectroscopy (XAS), electrical conductivity measurements and mass-spectrometry.

The opportunity of use nanostructural heterostructure n-SnO/sub 2/(Ni)/p-Si as a gas sensitivity element is investigated. The second derivative of the current-voltage characteristic of the heterostructure under influence of changes of gas environment and temperature were studied.

Heterostructures based on the nanometer-scaled semiconductor oxides can be used as gas-sensitive receptor and transducer systems. In comparison to resistive oxide sensors, having a linear current - voltage characteristics, the sensors based on the heterostructures show non-linear current - voltage characteristics. These structures, based on the industrially developed silicon technology, promise the new remarkable capabilities for the creation of the gas- and biosensitive sensors.

{100} surfaces, produced from sublimation grown PbS single crystals by cutting, mechanical and chemical polishing, were characterized with regard to topography, structure and chemical composition. For this purpose, some methods independent from another were used, for instance profile measuring, dislocation etching, X-ray rocking-curves, RHEED, Rutherford backscattering (RBS), and AES. The results allow to describe the change of structural perfection with the depth (damage depth), the concentration profile of the main components (half-quantitatively), and the significant decreasing of contamination. Following from this study, the model of the damage layer near the surface discussed earlier for PbTe is modified slightly.