Effect of the nature of the dopant element on the physical properties of X-PrCaMnO system (X = Cd, Sr, and Pb)

Abstract

The solid-state reaction method was used to fabricate Pr0.65Ca0.25X0.1MnO3 manganite compounds with X = Cd, Sr, and Pb. X-ray diffraction (XRD), magnetometry, and impedance spectroscopy technique are used to study the structural, magnetic, electrical, and dielectric properties. The X-ray diffraction reveals that all samples crystallize in the orthorhombic system. The magnetic measurements on all samples show the presence of charge ordering transition at high temperature followed by an antiferromagnetic transition. From dc-conductivity analysis, all samples display the presence of semiconductor behavior. It is observed that the lowest obtained value of the activation energy (Ea) corresponds to the Pb-doped sample. The activation energy deduced from the dc-conductivity (Ea)σ matches very well with that estimated from relaxation time (Ea)relax, indicating that the relaxation process and the electrical conduction are related to the same origin. For each X dopant, the ac-conductivity is obeyed to the Jonsher law. The analysis of the impedance spectra highlights the presence of non-Debye relaxation phenomenon. Dielectric results show that the Pb doped sample has better dielectric properties than Cd and Sr doped ones. The dielectric properties are strongly dependent on both temperature and frequency. Dielectric constants decrease with frequency, and their behaviors have been interpreted based on space charge polarization according to Maxwell-Wagner’s two-layer model. The observed high conductivity and high dielectric permittivity values suggest that our compounds may be suitable for applications in electronic devices.