Hydrocarbon gas sensing of nano-crystalline perovskite oxides LnFeO3 (Ln = La, Nd and Sm)

In this paper, we report the properties of the nano-crystalline oxides LnFeO3 (Ln = La, Nd and Sm) synthesized by sol–gel citrate technique. The crystalline structure of the oxides was analyzed by X-ray diffraction (XRD). The surface morphologies of the LnFeO3 thick-films on Al2O3 substrates were measured by scanning electron microscope (SEM). The gas-sensing characteristics of the oxides LnFeO3 were investigated in methane (CH4), propane (C3H8) and n-hexane (C6H14) gases. All LnFeO3-based sensors exhibited good HC sensing characteristics. The very high n-hexane sensitivities of NdFeO3 and SmFeO3-based sensors were discussed in terms of an important role of rare earth elements.