The Application of a Simple Synthesis Process to Obtain Trirutile-Type Cobalt Antimonate Powders and the Study of Their Electrical Properties in Propane Atmospheres for Use in Gas Sensors

The dynamic response in propane atmospheres at different voltages was investigated for samples made from powders of the semiconductor oxide CoSb2O6 synthesized using the microwave-assisted colloidal method. Powders of the compound calcined at 700 °C were studied with X-ray diffraction, confirming the CoSb2O6 crystalline phase. The microstructural characteristics of the oxide were analyzed using scanning and transmission electron microscopy (SEM/TEM), revealing a high abundance of nanorods, nanoplates, and irregular nanoparticles. These nanoparticles have an average size of ~21 nm. Using UV-Vis, absorption bands associated with the electronic transitions of the CoSb2O6’s characteristic bonds were identified, which yielded a bandgap value of ~1.8 eV. Raman spectroscopy identified vibrational bands corresponding to the oxide’s Sb–O and Co–O bonds. Dynamic sensing tests at 300 °C confirmed the material’s p-type semiconductor behavior, showing an increase in resistance upon exposure to propane. Critically, these tests revealed that the sensor’s baseline resistance and overall response are tunable by the applied voltage (1–12 V), with the highest sensitivity observed at the lowest voltages. This establishes a clear relationship between the electrical operating parameters and the sensing performance. The samples exhibited good operational stability, capacity, and efficiency, along with short response and recovery times. Extra-dry air (1500 cm3/min) was used as the carrier gas to stabilize the films’ surfaces during propane detection. These findings lead us to conclude that the CoSb2O6 could serve as an excellent gas detector.