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Structural, morphological and dielectric analyses of La1 − xSrxFeO3 solid solutions
Applied Physics A ( IF 2.5 ) Pub Date : 2021-08-30 , DOI: 10.1007/s00339-021-04825-x
R. Lataoui 1 , S. Zemni 1 , A. Triki 2 , S. Hcini 3 , J. Dhahri 4 , O. Kanoun 5
Affiliation  

Dielectric and conduction properties were investigated on La1 − xSrxFeO3 (0 ≤ x ≤ 0.5) ceramics synthesized by solid-state reaction method. X-ray powder diffraction pattern of all prepared samples and their Rietveld refinement revealed that all samples crystallize in orthorhombic structure with Pnma space group. Sr substitution induced the volume unit cell to decrease and the crystallite size to vary in a non-monotonic manner. Scanning electron microscopy images revealed also Sr-dependent morphology of the studied ceramics. Fourier transform infrared (FTIR) spectra evidenced structural distortion effects on νFe–O–Fe, σFe–O–Fe and νLa–O vibrations and showed the presence of the carbonate ion impurity for the compositions x = 0.2, 0.3, 0.4 and 0.5. Ac conductivity analysis was accomplished according to equation: \(\sigma_{ac} \left( \omega \right) = \frac{{\sigma_{s} }}{{1 + \tau^{2} \omega^{2} }} + \frac{{\sigma_{\infty } \tau^{2} \omega^{2} }}{{1 + \tau^{2} \omega^{2} }} + A \omega^{n}\) for the parent compound and its doped one La0.9Sr0.1FeO3. However, this analysis was realized by using Jonscher law: \(\sigma_{ac} \left( \omega \right) = \sigma_{dc} + A \omega^{n}\) for the compositions x = 0.2, 0.3, 0.4 and 0.5. It revealed that the hopping process occurred through long distance for 0 ≤ x ≤ 0.3 compositions, whereas for x = 0.4 and 0.5 compositions the hopping occurred between neighboring sites. Complex impedance analysis performed on these ceramics by means of different electrical equivalent circuits owing to their different morphologies allowed probing grain boundary effect on ac conductivity.



中文翻译:

La1 − xSrxFeO3 固溶体的结构、形态和介电分析

对 通过固相反应法合成的La 1 -  x Sr x FeO 3 (0 ≤  x ≤ 0.5) 陶瓷的介电和导电性能进行了研究。所有制备的样品的 X 射线粉末衍射图及其 Rietveld 精修表明,所有样品均以具有 Pnma 空间群的正交结构结晶。Sr 取代导致体积单位晶胞减少并且微晶尺寸以非单调方式变化。扫描电子显微镜图像还揭示了所研究陶瓷的 Sr 依赖性形态。傅里叶变换红外 (FTIR) 光谱证明了对ν Fe–O–Feσ Fe–O–Feν 的结构畸变影响La-O振动并表明组合物x  = 0.2、0.3、0.4 和 0.5存在碳酸根离子杂质。交流电导率分析根据等式完成:\(\sigma_{ac} \left( \omega \right) = \frac{{\sigma_{s} }}{{1 + \tau^{2} \omega^{ 2} }} + \frac{{\sigma_{\infty } \tau^{2} \omega^{2} }}{{1 + \tau^{2} \omega^{2} }} + A \ ω^{n}\)为母体化合物及其掺杂的 La 0.9 Sr 0.1 FeO 3。然而,这种分析是通过使用 Jonscher 定律实现的:\(\sigma_{ac} \left( \omega \right) = \sigma_{dc} + A \omega^{n}\)对于成分x = 0.2、0.3、0.4 和 0.5。结果表明,对于 0 ≤ x  ≤ 0.3 的成分,跳跃过程是通过长距离发生的 ,而对于x  = 0.4 和 0.5 的成分,跳跃过程发生在相邻站点之间。由于这些陶瓷的不同形态,通过不同的等效电路对这些陶瓷进行复阻抗分析,可以探测晶界对交流电导率的影响。

更新日期:2021-08-30
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