The targets of this project were two-fold: (1) the preparation of nanoparticles for sensors and (2) the preparation of prototype SnO2-based sensors. The mid-term target is involved with the preparation and characterization of tin oxide nanoparticles and nano-thin films, and the preparation and characterization of nano-gold and nano-silver particles from liquid phase method. Experimental results showed the flat-flame prepared tin oxide nanoparticles are spherical and with primary particle diameter of about 5nm. The XRD result indicated the formation of rutile phase tetragonal tin oxide nanoparticles. Gold and silver nanoparticles prepared by chemical reduction method yielded spherical, aggregated, narrowly distributed gold nanoparticles with a primary particle diameter of 10nm. In contrast, the silver nanoparticles are somewhat spherical, well dispersed, more broadly distributed, and with a primary particle diameter of 5-20nm. Gas phase generated nano-gold and nano-platinum were deposited onto tin oxide sensing elements. Tin oxide films were used either as-prepared from the flame or post-heated directly under the flame for sintering growth of the nano-tin oxide particles. The sensor performances of the four propotypes sensor were evaluated. Nano-Pt/SnO2 sensors of both as-prepared and sintered were found to exhibit the expected sensor performance, while nano-gold/SnO2 and nano-silver/SnO2 sensors showed the opposite trend, possibly due to enhanced sintering growth of nano-silver and nano-gold at an operating temperature too close to their melting points.

tin,oxide,,nanoparticle,sensor,,low-pressure,flat,flame