The Preparation, Characteration And Sensing Properties Of Nanocrystalline LaCo_xFe_1-xO₃(x=0.0-1.0)

In this paper, the author prepared the nanocrystallines LaCoxFe1-xO3(x=0.0-1.0)and La1-xSrxCo0.1Fe0.9O3(x=0.1-0.3) by sol-gel method. The crystal structure, particle size and surface properties of the samples were charactered by means of XRD, DTG-TA, SEM and BET. SEM result shows that the carbon nanotube-doped material has larger Average Pore Diameter than the undoped one.The C2H5OH gas sensor were fabricated.The results revealed that LaFeO3-based sensor is sensitive to C2H5OH, but the resistance is very high, which is a disadvantage in application. In order to decrease the resistance, we replace Fe with Co in B site. It shows that LaCo0.1Fe0.9O3 has the best sensitivity to C2H5OH. When the sintering temperature is 600℃and working current is 88mA, the LaCo0.1Fe0.9O3-based sensor has the best sensitivity:about 120 to 500ppm C2H5OH.However the response-recovery times were very long.We try to improve the sensitivity through dopping LaCo0.1Fe0.9O3 with carbon nanotube. And the results show that: the 5% carbon nanotube-doped sensor has a good sensitivity to C2H5OH, When the sintering temperature is 600℃and working current is 90mA, the 5% carbon nanotube-doped sensor has the best sensitivity:about 137 to 500ppm C2H5OH.The response-recovery times decreased as well: the response time is 10S, recovery time is 35S. The sensors also exibit better stability.