The Preparation And Study Of Limiting Current Oxygen Sensor With Dense Diffusion Barriers

As the core part of oxygen sensor,solid electrolyte plays a decisive role in the working temperature and performance of oxygen sensor.The solid electrolyte material of oxygen sensor is mainly composed of YSZ.However,the oxygen sensor can only work at a extremely high temperature,which may cause some problems,such as the hardly seal,high energy consumption,hard to choose the matched electrode materials and so on.In this paper,the La0.8Sr0.2Ga0.83Mg0.17O3-?(LSGM)was used as solid electrolyte material.The performance of the materials and the preparation of oxygen sensor were studied systematically.The main research and conclusions are shown as follows:First,the LSGM powder was prepared by a conventional solid-state reaction.the samples were sintered at seven temperature points(1200?1500?,with the intervals of 50?)for 20h,respectively.Some tests were carried out on these samples,such as line shrinkage rate,relative density,SEM,XRD,and conductivity.The characterization results exhibited that superficial nonporous micro-structure and tightly arranged gain can be observed for sample which sintered at 1450?,with its relative density was 96.5%.The XRD pattern exhibited a pure La0.8Sr0.2Ga0.83Mg0.17O3-? perovskite phase.The conductivity of LSGM at different temperature points(450?850? with the intervals of 50?)were all the highest,which was 0.068S/cm at 850?.Therefore,the sample sintered at 1450? revealed superior performance and was more suitable for the manufacture of the sensors than others.Second,the diffusion barrier powder of BCFN was prepared by a conventional solid-state reaction.The samples were sintered at 1150? for 10h.Some tests were carried out on these samples,such as relative density,SEM,phase,and conductivity.The characterization results showed that Superficial nonporous microstructure and Tightly arranged gain can be found for samples,with its relative density was 94.8%.The XRD pattern exhibited a pure perovskite phase.The conductivity of the samples were large.The BCFN were basically met the requirements of diffusion barrier usedin sensor.Third,limiting current oxygen sensors were fabricated with BCFN or LSM as diffusion barrier material and LSGM as solid electrolyte.When the tested oxygen concentration was in the ranged of 1%to 8%and tested temperature was 680?,the sensor with Ba0.9Co0.3Fe0.6Nb0.1O3-?(BCFN4)as its diffusion barrier material had limiting current platforms.The limiting current showed a linear dependence on oxygen concentration.Fourth,limiting current oxygen sensors were fabricated with LSGM or 8YSZ as diffusion barrier material and LSGM as solid electrolyte.When the oxygen concentration were in the ranged of 1%to 21%,the limiting current platforms were discovered with tested temperature were at 600? and 650?.However,The limiting current didn't show a linear dependence on oxygen concentration.