Dielectric relaxation and polaronic hopping in Mn-substituted LaSrNiO4 nickelates prepared by mechanical milling method

JOURNAL OF ALLOYS AND COMPOUNDS

卷:688

Article

Chouket, A.¹  Optasanu, V.²  Bidault, O.²  Cheikhrouhou, A.¹  Cheikhrouhou-Koubaa, W.¹  Khitouni, M.³ 

[1] Univ Sfax, Fac Sci Sfax, Lab Phys Mat, BP 1171, Sfax 3018, Tunisia

[2] Univ Bourgogne Franche Comte, CNRS, UMR 6303, Lab Interdisciplinaire Carnot Bourgogne ICB, 9 Av Alain Savary,BP 47870, F-21078 Dijon, France

[3] Univ Sfax, Fac Sci Sfax, Lab Chim Inorgan, Ur-11-Es-73,BP 1171, Sfax 3018, Tunisia

关键词: Mechanical milling method;    K2NiF4-type structure;    Rietveld refinement;    Dielectric measurements;    Equivalent circuit;   

DOI  :  10.1016/j.jallcom.2016.06.288

来源: Elsevier

【 摘 要 】

The structures, microstructures and dielectric properties of LaSrNi1-xMnxO4 (x = 0, 0.1, 0.2, 0.3 and 0.5) ceramics synthetized by mechanical milling followed by heat treatment were studied. One single tetragonal phase was revealed in all compounds. Structural parameters were obtained by Rietveld refinement. The substitution of Ni ions by Mn produces a variation of the lattice parameters but no phase change is observed. The surface morphology and elemental analysis of these samples were respectively investigated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray technique (EDS). Giant dielectric response was observed in these ceramics, and at least two relaxations were found on the curve of the temperature dependence of dielectric constant. An equivalent circuit [R-C][R-CPE] was used to fit the experimental data and provide the activation energy of the thermally activated relaxation. The activation energy values confirm the thermally activated small polaronic hopping contribution to the giant dielectric response. (C) 2016 Elsevier B.V. All rights reserved.

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