Consistency between theoretical conduction models and experimental conductivity measurements of strontium-doped lanthanum manganite

Abstract

La0.9Sr0.1MnO3 nanoparticles are elaborated using the citrate-gel route. The X-ray patterns show that the prepared sample crystallizes in the rhombohedral symmetry. Interesting results were obtained from the electrical conductivity measurements of the lanthanum manganite doped low strontium content. Indeed, numerous conduction models are used to analyze the electrical conductivity response. It is found that transport properties are governed by hopping processes at different temperature ranges. Such mechanisms explain the evolution of the DC-conductivity as well as the displacement of charge-carriers with temperature excitation. Then, thermal activation of the charge-carriers is confirmed. The temperature dependence of the frequency exponents reveals the contribution of Non-overlapping Small Polaron Tunneling (NSPT), Quantum Mechanical Tunneling (QMT), Over-lapping Large Polaron Tunneling (OLPT) and Correlated Barrier Hopping (CBH) to the transport properties. Conductivity spectrum shows a significant increase with frequency in the temperature range [80–500 K]. The frequency dependence of the AC-conductivity obeys to the "Double Jonscher Power Law" in the temperature range [80–300 K]. From 340 to 500 K, it is governed by the "Single Jonscher Power Law". Moreover, a high frequency plateau is observed presenting a percolation behavior in the conductivity spectrum. The deduced values of the disorder and hopping energies show the impact of hopping distance and polaron radius on the charge-carriers transport.