LPG sensing behavior and dielectric properties of lanthanum doped cobalt-iron oxide nano ferrite sensors towards room temperature detection at ppb level

Abstract

Herein, we report for the first time cost-effective synthesis of lanthanum doped cobalt-iron ferrite composite sensors towards the detection of liquified petroleum gas (LPG) at room temperature. The synthesized ferrite composites were characterized by different analytical techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy methods to analyse the surface morphology, elemental composition, functional groups, structural and optical properties. The synthesized ferrite composite exhibit improved ac conductivity and dielectric attributes due to the doping of rare earth (RE) lanthanum NPs into the cobalt-iron ferrites. Doping of lanthanum nanoparticle (NPs) into cobalt-iron ferrites result into porous surface with interconnected network which support for easy transportation of charge carriers into neighbouring sites. The gas sensing response of the lanthanum doped cobalt-iron ferrites was carried out at room temperature. The gas sensing properties of the synthesized CoFe2-xLaxO4 samples were studied for LPG, ethane, propane, butane, methane, and petrol vapours of variable hydrocarbon gas species. The CoFe2-xLaxO4 composite shows superior gas response towards LPG gas at room temperature. The gas response of CoFe2-xLaxO4 (x -0.1) composite sample was measured to be nearly 98% for LPG with enhanced response and recovery times. Furthermore, the long-term stability of these gas sensor towards LPG indicates that, that among the synthesized samples x - 0.1 composite samples show stable performance even after 60 days of operation. Owing to improved electrical conductivity, gas sensing behaviour and quick response and recovery times at room temperature, these CoFe2-xLaxO4 composites could be employed as suitable candidate towards fabrication of room temperature gas sensors especially for the detection of LPG at low concentration (ppb level).