Structural, conductivity, and complex impedance properties of the La0.7Ag0.3Mn1−xZnxO3 (x = 0 and x = 0.025) samples

Abstract

In this paper, the structural and dielectric properties of La0.7Ag0.3Mn1−xZnxO3 (x = 0 and 0.025) manganite system are investigated. The x-ray diffraction analysis confirms that all compounds crystallized in the rhombohedral structure with R3̄C space group. The effects of Zn substitution on the crystal structure and the dielectric properties were studied by using the impedance spectroscopy technique at room temperature and over a wide range of frequencies. Electrical conductance curves are found to obey the Jonscher universal power law. We note a decrease in the conductivity when increasing the Zn content from x = 0 to x = 0.025. This behavior can be associated with the introduction of a very low concentration of a non-magnetic Zn ion, which distorts the octahedral MnO6 neighbor. The analysis of the complex impedance spectra reveals a single semicircular arc reflecting a non-Debye-type relaxation process. We conclude from the best fits that the equivalent circuit formed in our case is defined as a grain resistance Rg in series with a parallel combination of grain boundary resistance Rgb and constant phase element impedance (ZCPE).