Abstract
In this paper, the structural and dielectric properties of La 0.7 Ag 0.3 Mn 1−x Zn x O 3 (x = 0 and 0.025) manganite system are investigated. The x-ray diffraction analysis confirms that all compounds crystallized in the rhombohedral structure with R[Formula: see text]C 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 MnO 6 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 R g in series with a parallel combination of grain boundary resistance R gb and constant phase element impedance (Z CPE ).