Paper NM-MoE3
Alumina Incorporated Tin Oxide (SnO₂) Pellets as Co Sensors

Monday, December 8, 2014, 6:20 pm, Room Hau

In this work we have utilized a novel Chemical-physical method for synthesis of SnO₂ nanoparticles. In two previous works [1,2], we have reported about the homogeneous precipitation synthesis of SnO₂ powders by two different precipitation agents, Urea and Ammonia; those powders were further ball milled to manufacture SnO₂ pellets and then tested for CO gas sensing. Compared to other methods [3-4] our synthesis route offers SnO₂ particles with very less agglomeration, particle size in the order of 15-20 nm, and homogeneous size distribution of the particles. An research group reported a maximum sensitivity for SnO₂ pellets around 8, for 1000 ppm of CO at operating temperatures of 300⁰C [5], whereas in our pellets, sensitivities were around 300 and 550 for CO when were measured at 300 ppm for 200and 300⁰C, respectively. Later the ball milled powders were mixed with Al₂O₃ powders (particle size around 1µm) with different ratios like 1:1, 2:1 and 4:1 in order to save tin oxide powder and also for increasing the oxygen trapping by increasing the porosity of the pellets. The effect of alumina mixing ratio on the pellets sensitivity was also studied. Maximum sensitivity obtained in pellets manufactured from ball milled SnO₂ powders, at 300 ⁰C for 300 ppm, by two different powder preparation routes were 548 and 262, whereas for mixing pellets with alumina at a 2:1 ratio (SnO₂:Al₂O₃), were 483 and 340, for the same two preparation methods. T he tendency of increasing the sensitivity with the operation temperature and the gas concentration was achieved successfully. The sensitivities obtained for pure ball milled SnO₂ and alumina 2:1 mixed pellets were almost in the same range. Therefore, high sensitivities can be achieved with less sensing material.

Keywords: Gas Sensors; Homogenous Precipitation; Sensitivity; CO, Pellets; Tin Oxide Powders.

References:

[1] Karthik, T.V.K. Maldonado, A., de la L Olvera, M., “Synthesis of tin oxide powders by homogeneous precipitation. Structural and morphological characterization”, IEEE Proceedings, Sept. 2012.

[2] Karthik, T.V.K. Maldonado, A., de la L Olvera, M., “ Manufacturing of Tin Oxide Pellets and their application for CO and C3H8 Gas Sensors ”, IEEE Proceedings, Sept. 2013.

[3] T. Seiyama, A. Kato, K. Fujiishi, and M. Nagatani, Anal. Chem. 34,1502 (1962).

[4] K. Ihokura and J. Watson, “The Stannic Oxide Gas Sensor—Principles and Applications.” CRC Press, Boca Raton, FL, 1994.

Presenting author’s email: krishnakarthik.tv@gmail.com