Structural and humidity sensing properties of niobium pentoxide-mixed nickel ferrite prepared by mechano-chemical mixing method

The influence of Nb₂O₅ on structural and humidity sensing properties of NiFe₂O₄ (NF) that has been prepared using mechano-chemical mixing of nickel ferrite with niobium pentoxide [NDNF] was analyzed. FTIR and XRD techniques analyzed the compositional properties of NF and NDNF composites. The appearance of characteristic absorption bands in the FTIR spectrum of NDNF composite with a small shift of NF and Nb₂O₅ confirmed Nb₂O₅ interfacial interaction with NF. XRD studies have confirmed phase of the sample. The average crystallite size varies from 13.54 to 30.12 nm. SEM images confirms the particles are agglomeration. Changes in the distribution of grain and the rise in intergranular pores in the composite for adsorption of water are verified by electron SEM images. Increasing nanosized particle agglomeration and enhanced composite crystallization have been verified by TEM images and SAED pattern. The particles size was found to be 12.75 and 13.5 nm for NiFe₂O₄ and NDNF3, respectively. NDNF3 Composites display a good sensing response of 1190 compare to 6 of NF within the 11% RH – 97% RH range. The NDNF3 composite response and recovery times were 20 s and 30 s, while the NF response and recovery times were 100 s and 140 s, respectively. The sensing process was analyzed based on chemisorption, physisorption and capillary condensation mechanisms. Nanocomposite samples demonstrated stable sensing ability and low hysteresis for humidity. Niobium pentoxide plays a major role in improving Nickel Ferrite's humidity sensing efficiency, therefore making the composite the best suitable for the use in humidity sensor devices.