Sensor fabrication calcination

Dieguez A., Romano-Rodriguez A., Morante 1. R., Kappler 1., Barsan N., and Gopel W., Nanoparticle engineering for gas sensor optimisation Improved sol-gel fabricated nanocrystalline SnOj thick film gas sensor for NO2 detection hy calcination, catalytic metal introduction and grinding treatments. Sens. Actuators B, 60, 125-137, 1999. 

As evident from Figure 2.25, the as-fabricated titanium dioxide thick films did not possess any well-defined microstructural features and hence were not attractive for the anticipated gas sensing applications. In order to make use of these simple geometries as potential gas sensor devices, the films were subjected to a series of heat-treatments in a weU-conceived temperature-time-enviromnent profile. The samples were calcined in static air at 700°C or 900°C for 4h each, or at 1100°C for 2h. The calcined samples were then reduced in a 5% H2/Ar mixture at 700°C for 6h in one case the reduction was carried out for 8h. 

A simple approach to prepare doped Ti02 powders relies on mixing a titanium alkoxide with a solution of the dopant precursor (namely, vanadium oxychloride) in dichloromethane. Then the solvent is evaporated, and either Ti isopropoxide or Ti tetrachloride is added. After reacting the final mixture with water and acetone, the powders are dried and calcined. Thick film sensors are fabricated by screen printing a paste of annealed powders surprisingly, the vanadium doping facilitates the anatase-rutile transition, in contrast to what has... 

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