Investigation of the Electrical Properties of Polycrystalline Crednerite CuMn1-xMgxO2 (x=0-0.06)-Type Materials in a Low-Frequency Field

CuMn1-xMgxO2 (x = 0-0.06) polycrystalline samples were prepared using the hydrothermal method at T = 100 degrees C for 24 h in Teflon-line stainless steel autoclaves. The samples were crystallized, forming crednerite structures (C2/m space group), and the Mg2+ substitution onto the Mn3+ site induced small changes in the unit cell parameters and volume. Based on complex impedance measurements made between 20 Hz and 2 MHz, at different concentrations of Mg ions (x), the electrical conductivity (sigma), the electric modulus (M), and the complex dielectric permittivity (epsilon) were determined. The conductivity spectrum, sigma(f, x), follows the Jonscher universal law and enables the determination of the static conductivity (sigma DC) of the samples. The results showed that, when increasing the concentration x from 0 to 6%, sigma DC varied from 15.36 x 10-5 S/m to 16.42 x 10-5 S/m, with a minimum of 4.85 x 10-5 S/m found at a concentration of x = 4%. Using variable range hopping (VRH) and correlated barrier hopping (CBH) theoretical models, the electrical mechanism in the samples was explained. The band gap energy (Wm), charge carrier mobility (mu), number density (NC) of effective charge carriers, and hopping frequency (omega h) were evaluated at different concentrations (x) of substitution with Mg. In addition, using measurements of the temperature dependence of sigma DC(T) between 300 and 400 K, the thermal activation energy (EA) of the samples was evaluated. Additionally, the dielectric behavior of the samples was explained by the interfacial relaxation process. This knowledge of the electrical properties of the CuMn1-xMgxO2 (x = 0-0.06) polycrystalline crednerite is of interest for their use in photocatalytic, electronic, or other applications.