Magnesium-substituted zinc ferrite as a promising nanomaterial for the development of humidity sensors

Herein, the synthesis of zinc ferrite (ZnFe${}_2$O${}_4$) nanomaterials, substituted with magnesium (Mg), using the sol-gel autocombustion method, is reported. Powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) are used to characterize the synthesized Mg-substituted ZnFe${}_2$O${}_4$. PXRD results show that unit cell volume and crystallite size decrease when the concentration of Mg ions rises. PXRD confirms that the nanomaterial has a single phase with the Fd3m space group. EDX confirms that the material is composed of Mg, Zn, Fe, and O elements. The FTIR spectra show a clear indication of the spinel ferrite structure, and the bands in the high-frequency region reveal the hygroscopic nature of the prepared materials. The synthesized nanomaterial is used as a sensing element for the development of a humidity sensor. The average sensitivity (2.93 MΩ/%RH) is found to be highest for the composition Mg${}_{0.1}$Zn${}_{0.9}$Fe${}_2$O${}_4$. The response and recovery times of the fabricated thin-film humidity sensor are 31 and 53 s, respectively. The developed sensing material has good repeatability (≈98%) and excellent stability. (© 2022 Wiley‐VCH GmbH)