Ethanol sensing characteristics of (La,Ba)(Fe,Ti)O3 nanoparticles with impurity phases of BaTiO3 and BaCO3

Abstract

To further improve the ethanol sensing performance of LaFeO3 (LFO) nanoparticles, the co-doping of acceptor and donor at La and Fe sites at equal mole amount was designed to increase the oxygen adsorbing ability of the resultant nanoparticles. A series of (La,Ba)(Fe,Ti)O3 nanoparticles, with the designed mole ratios of Ba/La (Ti/Fe) as 0, 0.25, 0.33, 0.50, and 1.0, were prepared by a citric sol–gel method. XRD confirmed the main phase of orthorhombic LFO, and the impurity phases of cubic BaTiO3 (BTO) and orthorhombic BaCO3. The incorporation of Ba and Ti into the LFO lattice was verified by the increased unit cell volume of LFO upon more doping. TEM, BET, and XPS measurements indicated that the appropriate co-doping of Ba and Ti into the LFO lattice and the simultaneous existence of BTO and BaCO3 resulted in smaller grain size, larger BET surface area, and thus higher concentration of adsorbed oxygen species than those in the pristine LFO nanoparticle. Among all (La,Ba)(Fe,Ti)O3 sensors, the sensor based on the (La,Ba)(Fe,Ti)O3 nanoparticles with the designed Ba/La = 0.50 exhibited the highest gas response and sensitivity toward ethanol at the prime working temperature of 132 °C, which was ascribed to the higher surface oxygen coverage contributed by the synergistic effect of co-doping and impurity phases on the number of surface active sites and oxygen adsorbing ability.