CO2-sensing characteristics of SnO2 thick film by coating lanthanum oxide

CO2 gas-sensor was fabricated by coating and heat-treating the drop of LaCl3 . 7H(2)O solution on the surface of SnO2 thick film. The effects of several factors, such as heat-treatment temperature, La concentration of coating-drop and humidity on CO2 sensitivity of thick film sensor were investigated in this work. The starting material, LaCl3 . 7H(2)O, for coating was phase-transformed by heat-treating, from LaCl3 to LaOCl at temperature range of 367-738 degrees C, and from LaOCl to La2O3 over 773 degrees C. The maximum sensitivity appeared at heat-treatment temperature of 1000 degrees C and La concentration of 1 x 10(-2) M La. The sensitivity showed a tendency to decrease remarkably with increasing humidity as well as with decreasing oxygen partial pressure. (C) 2000 Elsevier Science S.A. All rights reserved.