The K <sub> 2 </ Sub> The Nif <sub> 4 </ Sub> Structure Of Oxygen-sensitive Materials

It is considered that A₂BO₄ type material is one of the most probableoxygen-sensing materials. This material can form large amount of oxygen vacancies andbecomes non—chemical stoichiometric compound, therefore it shows relatively goodoxygen exchange and diffusion ability. Oxides La₂CuO₄ and La₂M_xCu_1-xO₄ (M=Ni,Co,Fe) were synthesized by the glycine-nitrates process (GNP), and oxide La_2-xSr_xCuO₄was synthesized by solid state reaction method in this thesis. The thick film typeoxygen-sensing sensor was fabricated and its oxygen-sensing properties wereinvestigated. The optimum thick-film oxygen-sensing sensor can be obtained byadjusting the process.(1)The highest sensitivity of thick-film La₂CuO₄ obtained at 400℃was 29.6,indicating the improved oxygen sensing property than the sintered bulk ones. Thecorresponding response time was about 4 seconds for the thick-film sensors at 400℃.Because the work temperature was low, so it was fit for the development of oxygensensor at low and intermediate temperature.(2)The results illustrate that thick film La₂Ni_0.1Cu_0.9O₄ (5wt% glass powder, 80μmthickness, sintering at 700℃) exhibits the best oxygen-sensing properties and has amaximum sensitivity of 7.1, the response time was about 16s, the recovery time wasabout 54min at 400℃.(3)The results illustrate that thick film La_1.2Sr_0.8CuO₄ (5wt% glass powder, 20μmthickness, sintering at 600℃) exhibits the best oxygen-sensing properties. It has amaximum sensitivity of 2.53 at 700℃. The response time was about 1.5s, and therecovery time was about 3.35min at 700℃. The experiment results show that these oxygen-sensing materials mentioned inthis thesis exhibit fast response to 1atm O₂. These materials are suitable for thedevelopment of oxygen sensors that can be used at low and intermediate operationtemperature in the future.