Particle Size Sorting of TiO₂ Powders Synthesized via Ultrasonic Atomization–Pyrolysis and Its Influence on Gas Sensing Properties

In this work, titanium dioxide (TiO₂) powder is synthesized using the ultrasonic atomization and pyrolysis technique. An ultrasonic atomizer having a resonance frequency of 2.4 MHz is used to convert the solution into fine mist. The mist was pushed into the horizontal double-zone quartz reactor furnace, and the pyrolysis temperature was optimized to get nanocrystalline powder. The prepared powders were collected into the traps attached to the rear end of the furnace. The powder named TiO₂_T1, TiO₂_T2, and TiO₂_T3, respectively, for the powders collected in traps 1, 2, and 3. The powders were analyzed by various characterization techniques such as X-ray diffraction to get their structural characteristics and scanning electron microscopy for microstructural information. The optical properties were analyzed by UV-Visible and photoluminescence spectroscopy. Thermal properties of the powders were studied by a simultaneous thermal analyzer. Thick films of the powders were prepared by the screen-printing method, and sensors were fabricated and tested for various gases. The sensor prepared from the powder collected in trap T3, i.e., TiO₂_T3, shows the highest response to NO₂ gas compared to the other sensors. The sensor also shows good response-recovery time. The results are analyzed and concluded in this article.