Synthesis and investigation of structural, dielectric, impedance, conductivity and humidity sensing properties of Cr3+-substituted Mg-Zn ferrite nanoparticle

In this study, structural, dielectric, impedance and humidity properties of Cr3+-doped Mg-Zn ferrite, produced by co-precipitation method, have been investigated. Structural, morphological and compositional analyses were studied by XRD, SEM and EDX, respectively. The X-ray diffraction result shows that Mg0.75Zn0.25Cr0.2Fe1.8O4 crystallizes in the cubic spinel structure with the space group of Fd3m. The lattice constant and crystal size of the sample were calculated as 8.4046 angstrom and 11.29 nm. The dielectric and impedance properties were investigated in the frequency range between 20 and 10 MHz and in the temperature range from 290 to 710 K. The dielectric results are supported by Maxwell-Wagner polarization principles. Relaxation mechanism of the sample is explained by Nyquist graph. According to the impedance results, relaxation process is compatible with Cole-Cole model. The conductivity mechanism of the sample is explained by the mechanism of correlated barrier hopping (CBH) model. Finally, the humidity sensing properties of sample were investigated by impedance measurements in the range of 25-90 RH % at room temperature.