Resistive-type lanthanum ferrite oxygen sensor based on nanoparticle-assimilated nanofiber architecture

This work offers new insights pertaining to an optimistic techno-commercial future for lanthanum ferrite perovskite-based oxygen sensors. A nanoparticle assimilated nanofiber architecture-based oxygen sensor is realized using LaFeO₃ as a functional material. Such chemiresistive oxygen sensor prototypes based on p-type LaFeO₃ are fabricated through the simple screen-printing of functional powders on an alumina substrate with prepatterned interdigitated Pt electrodes. The functional powders are produced using sol-gel and electrospinning. The chemical composition and morphology of the functional powders and their films sintered at 1050 °C are examined using scanning electron microscopy, X-ray diffraction, X-ray photoelectron microscopy, and Raman analysis. The oxygen gas sensing measurements demonstrate that the morphology has a significant effect on the ultimate sensor performance. An assembly of the mixed structure is the most effective for oxygen sensing at partial pressures in the range of 0–50 % in a harsh atmosphere at 650 °C. The highest response observed for the mixed morphology is 2.62 times that of its sol-gel powder counterpart. The long-term stability of the mixed morphology sample at 650 °C reveals excellent performance, with a minimum variation of ± 2 Ω over 100 h. These observations can be elucidated by a twofold mechanism involving ionosorption by an enhanced hole-accumulation layer and contact between connecting nanoparticles and nanofibers.