Conduction mechanisms and complex impedance analysis in La0.6Sr0.4FeO3 ceramic

IF 1.7 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Electroceramics Pub Date : 2023-04-28 DOI:10.1007/s10832-023-00310-4

R. Lataoui, A. Triki, S. Hcini, A. Oueslati, S. Zemni, O. Kanoun

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Abstract

La_0.6Sr_0.4FeO₃ ceramic was elaborated by solid-state route. Preliminary room-temperature structural analysis evidences the sample formation in the orthorhombic structure and its phase purity. Electrical properties of the studied ceramic have been investigated according to dielectric measurements in the frequency range 10^–1 - 10⁶ Hz and the temperature range 93 - 313 K. Electrical conductivity curves exhibit a step-like behavior, at low temperatures, attributed to grain boundaries and grain contributions which are well described by the two Jonscher equations. The grains conduction mechanism is consistent with the thermally activated hopping of small polaron (SPH). Whereas, this mechanism is no longer satisfied for grain boundaries conduction mechanism at lower temperatures. Indeed, this latter is governed by the variable range hopping (VRH) model. This electrical conductivity analysis is further confirmed by the complex impedance formalism according to the obtained activation energies. Analysis of Nyquist plots at low temperatures has evidenced the presence of two grain boundaries effects attributed to the heterogeneous structure of La_0.6Sr_0.4FeO₃ grain boundary according to the morphological analysis_. Such characteristic may be at the origin of the grain boundaries electrical conductivity mechanism change at low temperatures.

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La0.6Sr0.4FeO3陶瓷的传导机理及复杂阻抗分析

采用固态法制备La0.6Sr0.4FeO3陶瓷。初步的室温结构分析证实了样品的正交结构形成及其相纯度。在10-1 ~ 106 Hz的频率范围和93 ~ 313 K的温度范围内对所研究陶瓷的电学性能进行了测试。在低温下，电导率曲线表现出阶梯状的行为，这归因于两个Jonscher方程很好地描述的晶界和晶粒贡献。晶粒的传导机制与小极化子(SPH)的热激活跳变一致。然而，在较低温度下，这一机制不再满足晶界传导机制。实际上，后者是由可变范围跳变(VRH)模型控制的。根据得到的活化能，复阻抗形式进一步证实了这一电导率分析。低温下Nyquist图的形貌分析表明，La0.6Sr0.4FeO3晶界存在两种非均质结构的晶界效应。这种特性可能是低温下晶界电导率机制变化的根源。

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来源期刊

Journal of Electroceramics 工程技术-材料科学：硅酸盐

CiteScore

2.80

自引率

5.90%

发文量

审稿时长

5.7 months

期刊介绍： While ceramics have traditionally been admired for their mechanical, chemical and thermal stability, their unique electrical, optical and magnetic properties have become of increasing importance in many key technologies including communications, energy conversion and storage, electronics and automation. Electroceramics benefit greatly from their versatility in properties including: -insulating to metallic and fast ion conductivity -piezo-, ferro-, and pyro-electricity -electro- and nonlinear optical properties -feromagnetism. When combined with thermal, mechanical, and chemical stability, these properties often render them the materials of choice. The Journal of Electroceramics is dedicated to providing a forum of discussion cutting across issues in electrical, optical, and magnetic ceramics. Driven by the need for miniaturization, cost, and enhanced functionality, the field of electroceramics is growing rapidly in many new directions. The Journal encourages discussions of resultant trends concerning silicon-electroceramic integration, nanotechnology, ceramic-polymer composites, grain boundary and defect engineering, etc.