Effect of Eu3+ and Sc3+ on the structure, microstructure and humidity sensing properties of copper ferrites for sensor applications

Abstract

In this investigation, we studied the effect of rare lanthanides on the structure, microstructure, and humidity sensing characteristics of CuEuxScyFe(2-x)O4 ceramics with the following x = y values: 0.00, 0.01, 0.02, and 0.03. The preparation of the samples was accomplished through the utilization of the solution combustion method. The X-ray diffraction (XRD) patterns show the main cubic spinel crystal structure with the space group Fd3‾m with an additional second Fe2O3 phase. The estimated average spinel crystallite size varied from 25 to 10 nm across doping. The microstructure studied by scanning electron microscopy (SEM) proved the porous nature of CuEuxScyFe(2-x)O4 with agglomerated particles. The resistance and the humidity sensing responses become more evident for higher concentrations of Eu–Sc. As demonstrated by the hysteresis curves, the desorption process proceeds somewhat slower than the adsorption process. As recorded, the sensor response and recovery times were each clocked at 39 and 40 s, respectively.