Ammonia sensor based on NASICON and Cr2O3 electrode

A compact tubular sensor based on NASICON (sodium super ionic conductor) and porous Cr2O3 sensing electrode was designed for the detection of ammonia. The sensor gave excellent sensing properties to 50-500 ppm ammonia in air at 250-450 C. The EMF value of the sensor was almost proportional to the logarithm of ammonia concentration, the sensitivity (slope) was -89 mV/decade at 350 C. It was also seen that the sensor showed a good selectivity to ammonia, and an excellent resistance to water vapor, The sensor had speedy response kinetics to ammonia, the 90% response time to 50 ppm ammonia was 30 s, and the recovery time was 60 s. (C) 2008 Elsevier B.V. All rights reserved.