The Properties And Fabrication Of Gas Sensors Based On LnFeO₃?Ln=La,Nd,Sm?

As people pay more attention to air pollution and health,gas sensor technology is developing rapidly.Especially,in the field of automobile exhaust detection,the environment harmful gas,drunk driving test,coal mine safety and other aspects,gas sensing technology play a huge role.Therefore,efficient,fast,stable and safe gas sensor is still the focus of research and development direction of sensor technology.In this paper,Ln FeO₃?Ln= La,Nd and Sm?nanofibers are made to side-heating resistance type gas sensor,and Pt/YSZ/LnFeO₃ mixed potential type gas sensor with Y2O₃-stabilized ZrO₂?YSZ?,and the sensitive mechanisms are analyzed,to investigating the effect of lanthanide on acetone sensing properties of Ln Fe O₃ nanofibers resistance and the mixed potential type sensor.The main research contents are summarized as follows.1.LnFeO₃?Ln= La,Nd and Sm?nanofibers are synthesized by the electrospinning,and characterized by X-ray diffraction?XRD?,field-emission scanning electron microscopy?FE-SEM?and X-ray photoelectron spectroscopy?XPS?.For investigating the effect of lanthanide on acetone sensing properties of LnFeO₃ nanofibers,the side-heating gas sensors based on Ln Fe O₃ nanofibers are fabricated and measured at different temperatures and acetone concentrations.The optimal working temperatures of the LnFeO₃ gas sensors are all140 °C.When the Ln Fe O₃ gas sensors are exposed to 100 ppm acetone at 140 °C,the SmFeO₃ gas sensor exhibits the largest sensing response?Response = 9.98?compared with LaFeO₃ and NdFeO₃ gas sensors,and the response and recovery times of SmFeO₃ gas sensor are about 17 s and 16 s,respectively.The results indicate that the lanthanides have an impact on acetone sensing properties of LnFeO₃,and the lanthanide with low binding energy of the Ln–O bond is beneficial for improving the acetone sensing properties of LnFeO₃.Our studies may provide a useful guidance for improving preparation process of gas sensing materials.2.8mol% Y2O₃-stabilized ZrO₂?YSZ?nanoparticles are synthesized by the sol-gel method,and characterized by XRD and FE-SEM.For investigating the effect of lanthanide on NO₂ sensing properties of LnFeO₃ nanofibers mixed potential type sensor,the mixed potential type NO₂ gas sensors are fabricated using LnFeO₃ nanofibers as sensing electrode,8mol% YSZ as electrolyte and platinum?Pt?as reference electrode.The gas sensing properties of the mixed-potential type NO₂ gas sensors are investigated by exposing the gas sensor to the test chamber at different operating temperatures and NO₂ concentrations.The results show that the SmFeO₃ gas sensor is of maximum response value?45 mV?to 200 ppmNO₂ at 330 °C,compared with LaFeO₃ and NdFeO₃ gas sensors and the response and recovery times are about 6 s and 6 s.The Sm FeO₃ sensor exhibit a nearly linear response at NO₂ concentrations range of 10-200 ppm,and the slope reaches up to 31 mV/decade.We expect that our works can offer useful guidelines to fabricate high performances mixed-potential type NO₂ gas sensors.