Investigation of optical, dielectric properties and conduction mechanism of LiCo0.7Mn0.3O2

Abstract

The development of a multifunctional material with variety in its properties is a powerful research project. The electrochemical properties of LiCo0.7Mn0.3O2 material have attracted our attention to search electrical characterization and the optical properties of this material. The synthesis of this compound is based on a solid state method. The x-ray powder diffraction analysis shows that the compound crystallizes in the hexagonal system with the R −3 m space group. Moreover, the homogenous distribution of grain is revealed by the EDX study, thus the grain size is about 2.5 μm calculated from the scanning electron microscopy data. The band gap energy was established and seems to be equal to 1.88 eV which confirms the semiconductor character of this compound. Impedance spectroscopy was performed in the temperature ranging from 363 K to 473 K and frequency varying between 0.1 to 106Hz. The Nyquist plots confirm the presence of grains and grain boundary contribution instead of electrode polarization. The obtained conductivity properties indicates the semiconductor behavior of our compound, also it confirms its reliability for electrochemical application. Ac conductivity has been adjusted using the Jonsher power law, which allows us to confirm that the dc conductivity is thermally activated with activation energy of 400 meV and 500 meV for 363–423 K, 423–473 K regions, respectively. Temperature dependence of the exponent s reveals that the conduction process is governed by the correlated barrier hopping model (CBH). Besides, the temperature coefficient of resistivity (TCR) affirmed that LiCo0.7Mn0.3O2 is a good candidate for bolometric applications.