Synthesis of ZnGa2O4 assisted by high-energy ball milling and its gas-sensing characteristics

Mass production of ZnGa 2 O 4 has been successfully achieved via a simple solid state reaction assisted by high-energy ball-milling of mixtures of ZnO and GaOOH powder at room temperature. The samples were characterized in detail to confirm the formation of ZnGa 2 O 4 . It could be concluded from the result of X-ray diffraction patterns that the crystal formation started after milling for 5   h, and it was completed after 7   h. The average diameter of the as-prepared ZnGa 2 O 4 is less than 100   nm. To demonstrate the potential applications, we have fabricated a gas sensor based on the as-synthesized ZnGa 2 O 4 and investigated it for liquid petroleum gas (LPG) and nitrogen dioxide gas (NO 2 ) detection at different working temperatures. ZnGa 2 O 4 sensors exhibited a gas response ( R a / R g   =   7.9, R a : resistance in air, R g : resistance in gas) to 50   ppm of LPG at working temperature 340   °C, and a superior gas response ( Rg / Ra   =   16.2) to 5   ppm of NO 2 at 240   °C. Preliminary functional tests indicated promising sensing responses and the possibility of discriminating between reducing and oxidizing species as a function of the working temperature.