Investigation of magnesium substituted nano particle zinc ferrites for relative humidity sensors

Nano particle Spinel ferrites, the magnetic semiconductor, are exhibiting remarkable surface phenomenon, wherein the process of adsorption is most significant. Humidity sensing is the realization of adsorption mechanism. Therefore, ferrites would be suitable for humidity sensing applications. Considering this fact into account, the compositions of polycrystalline Mg-Zn ferrites have been prepared by chemical route and characterized by standards tools like X-ray powder diffraction and FTIR spectroscopy. From the results of X-ray diffraction investigation, formation of single phase compositions is confirmed. The resulted structure is FCC with 311 as a prominent reflection. Average particle size obtained by using Scherrer method is within the range from 40 nm to 48 nm. The existence of the nanoparticles results into increase of the surface area required to favour adsorption mechanism. The significant absorption bands were observed for higher range of frequencies in FTIR, which are attributed to the modes of vibration of water molecules. Therefore, it can be used for development of the humidity sensor. The relative humidity sensor is designed by depositing thick film of the materials under investigation on ceramic substrate. Electrical resistance of the sensor (RH) reveals decreasing trend with increase in the relative humidity. Relative deviation in the resistance (RDR) with humidity depicts two significant regions attributed to the existence of protonic conduction mechanism. The sensor, developed from x = 0.40, reveals good linearity over wide range of humidity from 40%RH to 75%RH, which suggests its suitability for sensor development. Moreover, the features of the composition for x = 0.40 is suitable for design of electronic interfaces required for instrumentation. The sensitivities of the compositions less than 1 s for 10% variation in the relative humidity. This confirms that the humidity sensors developed by employing compositions of ferrite on ceramic substrate are very fast and reliable.