Impact of Sintering Temperature on the Electrical Properties of La_0.9Sr_0.1MnO₃ Manganite

Abstract

La0.9Sr0.1MnO3 nanoparticles were prepared using the citrate–gel route and sintered at different temperatures (TS = 600 °C, 800 °C, and 1000 °C). The x-day diffraction patterns reveal that the samples exhibit a single phase with a rhombohedral (R3¯C) structure. The transmission electron microscopy technique shows an increase in the grain size when the sintering temperature (TS) rises. The obtained values are approximately similar to that of crystallite size calculated from x-ray diffraction patterns. The impact of sintering temperature (TS) on the electrical properties of La0.9Sr0.1MnO3manganite is examined using the impedance spectroscopy technique. A metal-semi-conductor transition at a specific temperature (TM-SC) is observed for all samples. Indeed, the sintering temperature increase induces the shift of this transition temperature toward higher temperatures. Such a behavior is explained by the increase in the grain size. An agreement between the metal-semi-conductor transition values coming from the DC resistivity and the grain boundaries analyses is observed. This agreement proves the contribution of the grain boundaries in the electrical properties of the studied samples. In addition, the presence of the relaxation phenomenon is confirmed. The fitted Nyquist plots show the correlation between the microstructure of the material and the electrical properties using an electrical equivalent circuit model. The DC resistivity and the impedance analyses reveal the thermal activation of the transport properties in the investigated system.

Keywords

• manganite
• sintering temperature
• impedance spectroscopy
• electrical resistivity