Electrodeposited and Sol-gel Precipitated p-type SrTi_1-xFe_xO_3-δ Semiconductors for Gas Sensing

In the present contribution, three methods for the preparation of nanoscaledSrTi_1-xFe_xO_3-δ sensor films for hydrocarbon sensing were investigated. Besides screen-printed thick films based on sol-precipitated nanopowders, two novel synthesis methods,electrospinning and electrospraying, were tested successfully. All of these sensor devicesshowed improved sensor functionality in comparison to conventional microscaled thickfilms. In order to explain the impact of the enhanced surface-to-volume ratio on sensorproperties in a quantitative way, a mechanistic model was applied to micro- and nanoscaleddevices. In contrast to the conventional diffusion-reaction model that has been proposed forn-type semiconducting sensors, it contained novel approaches with respect to themicroscopic mechanism. With very few fit variables, the present model was found torepresent well sensor functionality of p-type conducting SrTi_0.8Fe_0.2O_3-δ films. In additionto the temperature dependency of the sensor response, the effect of the specific surface areaon the sensor response was predicted.