Electromagnetic Properties and Humidity-Sensing Studies of Magnetically Recoverable LaMg x Fe1−x O 3−δ Perovskites Nano-photocatalysts by Sol-Gel Route

Abstract

Nanostructured perovskite mixed metal oxides, LaMg x Fe1−x O 3−δ (x= 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0), were synthesized successfully by a simple sol-gel route. The formation of single-phase perovskite oxides structure was confirmed by powder X-ray diffraction (XRD) analysis. The average crystallite size of the samples was evaluated using Sherrer’s formula. The presence of functional groups and metal oxide bonds was confirmed by Fourier transform infrared (FT-IR) analysis. Brunauer-Emmett-Teller (BET) surface adsorption studies showed better surface area of the compositions, which was further, evidenced by scanning electron microscopy (SEM) analysis. Room temperature vibrating sample magnetometer (VSM) analysis was confirmed that the superparamagnetic nature and the magnetization values decreased with increase in Mg-dopant. The samples were subjected to dc electrical conductivity studies at room temperature. The dc resistance measurements as a function of relative humidity (RH) at 5, 31, 51, 79, and 98 % were carried out on sintered discs at 25 ∘C under static conditions, which sensitivity factor S f (R 5% / R 95%) were calculated for LaMg x Fe1−x O 3−δ . The temperature-dependent conductance was also carried out in the range of 100–300 ∘C as suggested, and the activation energy was determined. Sample LaMgFe-4 (x= 0.6) possessed the highest humidity-sensing factor (12,926.03 ± 387), while LaFeO3 (x= 0) possessed the lowest sensitivity factor (41.66 ± 3). The response and recovery characteristics were studied for LaMgFe-4, which exhibited a very good narrow hysteresis loop. The photocatalytic degradation (PCD) of methylene blue (MB) dye was investigated under UV-visible light and the sample LaMgFe-4 showed better PCD efficiency than other samples, due to the smaller particle size and higher surface area.