Synthesis and Study of Highly Porous Nature Gadolinium Doped CoCr₂O₄: Focus on the Structural, Microstructural, Electric, and Humidity Sensing Properties

Abstract: In this paper, we presented structural, Fourier infrared spectroscopic, and dielectric analysis of cobalt chromate (Co²⁺Cr³⁺₂₄) with 2 mol % of gadolinium (Gd³⁺) rare earth metal additions under humidity and non-humidity circumstances. The Gd³⁺ doped Co²⁺Cr³⁺₂₄ samples were prepared by solution combustion method and sintered for 2 h at 650°C to get single phase. Doped and undoped samples were characterized by X-ray powder diffraction (XRD) analysis providing the detailed information of the Co²⁺Cr³⁺₂₄ phase and crystallinity. Furthermore, the average crystallite sizes were found to be in the range of 18 to 7 nm. The general nature of ferrite materials was revealed via FTIR analysis. The octahedral and tetrahedral stretching band in FTIR spectra were confirmed a ferrite structure without impurity. Scanning electron microscopic images exhibited that samples are highly porosity. We investigated the relevant conductivity of the samples, the reaction time of the capacitive sensor, and the humidity influence on the relative permittivity characteristics at a constant frequency of 1 kHz. Our findings indicate that Gd³⁺ doped Co²⁺Cr³⁺₂₄ could be exploited as an active material in humidity sensor applications.