Synthesis, characterization, and sensitivity tests of a novel sensor based on barium antimonate powders

Barium antimonate (BaSb₂O₆) powders were prepared using a microwave-assisted wet chemistry process. The powders were calcined at 800 °C and their crystallinity was studied by X-ray diffraction, finding a hexagonal crystal structure with cell parameters a = 5.303 Å and c = 5.758 Å, and a P-31m (162) space group. Material's morphology and particle size were analyzed by field-emission scanning and transmission electron microscopy, finding that nano-plates (~ 70 nm) and other apparently shapeless particles (~ 70 nm) were produced. By means of X-Ray Photoelectron Spectroscopy, it was found that the Ba 3d had a doublet (Ba 3d_5/2 and Ba 3d_3/2) with binding energies at 779.69 and 794.97 eV, respectively, which was associated with the Ba²⁺ oxidation state. The Sb 3d spectrum presented a doublet (Sb 3d_5/2 and Sb 3d_3/2) at 530.44 and 539.79 eV, while the O 1 s at 530.30 eV overlapped the Sb 3d_5/2 peak. Photoacoustic Spectroscopy measurements of the oxide showed a band gap of 3.43 eV. Pellets manufactured with BaSb₂O₆’s powders calcined at 800 °C were tested in CO (1–300 ppm) and C₃H₈ (1–500 ppm) atmospheres at different operating temperatures (100, 200 and 300 °C). The pellets exhibited an excellent response, showing a high sensitivity as concentrations and temperature increased. Furthermore, the results indicated that the BaSb₂O₆ is highly selective to CO atmospheres. In particular, the good response of the pellets suggests that this oxide can be applied as a potential sensor for toxic gases.