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This article reveals the crucial structural, magnetic, and electrical properties of La0.7Sr0.25Na0.05Mn0.8Ti0.2O3 (LSNMTO) manganite, highlighting the significance of this material in the field of materials science. Gain a deeper understanding of the promising properties of LSNMTO and its potential for technological advancement by delving into this informative article. The X-ray diffraction data of the LSNMTO indicate that this ceramic solid solution crystallizes in the R3Ìc rhombohedral structure. The magnetic results confidently demonstrate that the LSNMTO ceramic undergoes a transition from paramagnetic to ferromagnetic phases around 125 K. This significant finding could pave the way for further progress in the field of materials science. The DC conductivity response confirms the semiconductor nature of the elaborated compound over the studied temperature domain. Such behavior is linked to the contribution of the small polaron hopping mechanism at elevated temperatures and the Shklovskii Efros variable range hopping process at low temperatures. In the limit of the AC regime, the temperature-dependent AC conductivity confirms the appearance of a metal-semiconductor behavior at T M-S = 120 K that confirms the strong correlations between the transport and the magnetic properties of the sample. Over the explored temperature domain, the conductivity spectra follow a power law-like behavior. The scaled conductivity curve of LSNMTO is not superimposed on the particle grains' restricted reaction area. The Summerfield scaling of the electrical conductivity confirms with confidence the significant contribution of carrier concentration to the overall conduction of the material.
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The present work proposes the best realistic theoretical approaches to examine the experimental conductivity data taken for La0.55Ca0.45Mn0.8Nb0.2O3. For this purpose, we comprehensively discussed the structural, microstructural, and electrical properties of the La0.55Ca0.45Mn0.8Nb0.2O3 perovskite. Both X-ray diffraction and Rietveld analysis show the orthorhombic structure of the ceramic. Scanning electron microscope showed the existence of well-defined irregularly shaped particles with a grain-size distribution of 0.843 µm. The X-ray photoemission spectroscopy reveals the existence of Mn3+ and Mn4+ states. The complicated behavior of the lanthanum states is demonstrated using the La3d line. AC-conductivity responses are related to the correlated barrier hopping contribution. At high temperatures, the compound's semiconductor behavior is attributed to the activation of the polaronic transport. At low temperatures, the occurrence of semiconductor behavior in the La0.55Ca0.45Mn0.8Nb0.2O3 ceramic is attributed to the effect of the variable range hopping conduction process. The application of the time-temperature-superposition-principle and the Summerfield scaling formalisms leads to the superposition of the isotherms. Using the Ghosh formalism, the superposition of the spectra confirms that the number density and the hopping distance are temperature-dependent. The superposition of the spectra suggested the temperature-independent relaxation and polaronic processes. In addition, it confirms that the relaxation mechanism is independent of the microstructure response.
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Electrical properties of Pr0.7Ca0.3Mn0.9X0.1O3 (X = Co, Ni, Cr and Fe) systems have been investigated using impedance spectroscopy measurements. The reported results confirmed the role of cationic disorder on the transport properties of the doped Pr0.7Ca0.3MnO3 system. For the case of the substitution by Co and Ni and Fe transition metals, the lower temperature side has been marked by the activation of the hopping conductivity over the nearest sites. Moreover, the Shklovskii-Efros-variable range hopping conductivity mechanism has been observed in the case of the substitution by Cr element. In the high temperature range, the evolution of the resistance with temperature confirmed the activation of a hopping process. In such a temperature range, the conduction process of all the studied compounds is dominated by a thermally activated small polaron hopping mechanism. For the Pr0.7Ca0.3Mn0.9Cr0.1O3 compound, AC studies have confirmed that the electrical conductance should be investigated in terms of an activated quantum mechanical tunneling process. At higher frequencies, the Pr0.7Ca0.3Mn0.9Fe0.1O3 compound is characterized by the existence of a high frequency plateau. For the Pr0.7Ca0.3Mn0.9Fe0.1O3 ceramic, the dispersive region of the spectrum has confirmed the activation of the correlated barrier hopping mechanism. Thus, the conductance is found to follow the double Jonscher power law only for the temperature range of [80 K, 200 K]. For the Pr0.7Ca0.3Mn0.9Ni0.1O3 compound, the evolution of the frequency exponent has confirmed the activation of two conduction mechanisms. The non small polaron tunneling mechanism was activated at lower temperatures. Accordingly, the activation of the correlated barrier hopping mechanism was detected for the high temperature range. For Pr0.7Ca0.3Mn0.9Co0.1O3 manganite, the coexistence of two conduction mechanisms (correlated barrier hopping and the non small polaron tunneling) is noticed. The latter's were activated in the whole of the explored temperature range. Using the scaling model, the spectra of both Pr0.7Ca0.3Mn0.9Cr0.1O3 and Pr0.7Ca0.3Mn0.9Ni0.1O3 compounds merge into a single master curve, which confirms the validity of the time temperature superposition principle.