ИСТИНА

It is known that TiO2 is not widely used as a sensitive material for gas sensors due to its high resistivity. However, its characteristics are stable, since it has low ion diffusion coefficients, and the problem of low conductivity can be solved by n-type or p-type doping. This work is devoted to the study of the effect of chromium (III) doping both on the structural and electrical characteristics of TiO2 as well as on its sensory properties in relation to gases and volatile organic compounds (VOCs). The TiO2 nanomaterials containing up to 40mol% Cr were synthesized using flame spray pyrolysis. Materials are investigated by XRD, TEM, XPS, XRF, BET, TPR-H2, Raman, EPR and optical spectroscopy, in situ conductivity measurements. It is shown that the formation of a substitutional solid solution of Cr-TiO2 leads to an increase in the proportion of the rutile phase and specific surface area of TiO2, a change in the charge state of Ti and Cr and in the concentration of oxygen vacancies in the bulk and surface as well as to transition to p-type conductivity. It is shown that pure TiO2 and pure Cr2O3 do not show high responses, while Cr(III) doped TiO2 materials are characterized by reasonable response values, response and recovery times and selectivity for detection a low concentrations of VOCs in a humid atmosphere. Key words: gas sensors, semiconductors, titanium dioxide, doping, sub-ppm concentration.