Electrodeposited and Sol-gel Precipitated p-type SrTi(1-)(x)Fe(x)O(3-δ) Semiconductors for Gas Sensing

In the present contribution, three methods for the preparation of nanoscaled SrTi(1-)(x)Fe(x)O(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 devices showed improved sensor functionality in comparison to conventional microscaled thick films. In order to explain the impact of the enhanced surface-to-volume ratio on sensor properties in a quantitative way, a mechanistic model was applied to micro- and nanoscaled devices. In contrast to the conventional diffusion-reaction model that has been proposed for n-type semiconducting sensors, it contained novel approaches with respect to the microscopic mechanism. With very few fit variables, the present model was found to represent well sensor functionality of p-type conducting SrTi(0.8)Fe(0.2)O(3-δ) films. In addition to the temperature dependency of the sensor response, the effect of the specific surface area on the sensor response was predicted.