Synthesis of ZnAl2O4 and evaluation of the response in propane atmospheres of pellets and thick films manufactured with powders of the oxide

Abstract

ZnAl2O4 nanoparticles were synthesized employing a colloidal method. The oxide powders were obtained at 300◦C, and their crystalline phase was corroborated by X-ray diffraction. The composition and chemical structure of the ZnAl2O4 was carried out by X-ray and photoelectron spectroscopy (XPS). The optical properties were studied by UV-vis spectroscopy, confirming that the ZnAl2O4 nanoparticles had a direct transition with bandgap energy of 3.2 eV. The oxide’s mi-crostructures were microbars of ~18.2 nm in size (on average), as analyzed by scanning (SEM) and transmission (TEM) electron microscopies. Dynamic and stationary gas detection tests were per-formed in controlled propane atmospheres, obtaining variations concerning the concentration of the test gas and the operating temperature. The optimum temperatures for detecting propane concentrations were 200 and 300◦C. In the static test results, the ZnAl2O4 showed increases in propane response since changes in the material’s electrical conductance were recorded (conductance = 1/electrical re-sistance, Ω). The increases were ~2.8 at 200◦C and ~7.8 at 300◦C. The yield shown by the ZnAl2O4 nanoparticles for detecting propane concentrations was optimal compared to other similar oxides categorized as potential gas sensors.