Gas Sensing with Perovskite-like Oxides Having ABO3 and BO3 Structures

WO3 and LaFeO3 are considered as example oxides in gas sensing, respectively of perovskitelike BO3 and ABO3 oxide groups, the structural chemistry of which is based on corner-sharing octahedral oxygen networks where transition metal cations B occupy the octahedral cages of oxygen anioins. WO3 is an n-type semiconductor and many magnetic perovskites like LaFeO3 are p-type semiconductors. There is a great flexibility inherent in the structure of both oxide groups which gives a lot of possibilities for structure engineering of the oxides for gas-sensing applications, e.g., by a temperature treatment or by modifying with impurity atoms. We have used here a high-temperature process, advanced reactive gas deposition, to produce nanoparticle thick films of WO3 with the metastable tetragonal crystal structure at low temperatures up to 300–400∘C, and sol-gel citrate method to produce nanocrystalline LaFeO3 powder as pure and modified with Sr and Mg, respectively.