Assessment of structural, morphological, magnetic and gas sensing properties of CoFe2O4 thin films

Polycrystalline CoFe2O4 thin films are deposited onto the quartz substrates by spray pyrolysis technique. Rietveld refinement analysis confirmed the films are polycrystalline in nature with spinel cubic crystal structure. Rietveld refinement analysis was employed to estimate the cation distribution in spinel lattice sites. Surface micrographs shows the granular morphology with average grain size decreases with increase in solution concentration. The presence of two characteristic absorption bands around 579 and 391 cm(-1) in the FTIR study confirms the formation of single phase CoFe2O4. Vibrating sample magnetometer measurement confirmed the predominant ferrimagnetic nature of thin films which confirms the maximum saturation magnetization with moderate coercivity was useful for making effective gas sensor. The gas response towards different operating temperatures, gas concentrations and solution concentrations was systematically studied. The films show the maximum gas response 70% at 0.1 M solution concentration at 150 degrees C operating temperature. The films are well selective towards NO2 as compared with other test gases with good reproducibility. (C) 2017 Elsevier Inc. All rights reserved.