Effect of Al³⁺ substitution on structural, cation distribution, electrical and magnetic properties of CoFe₂O₄

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• 作者：Rabia P ; it ; K.K. Sharma ; Pawanpreet Kaur ; R.K. Kotnala ; Jyoti Shah ; Ravi Kumar
• 关键词：Ferrites ; Cation distribution ; Rietveld refinement ; Dielectric response
• 刊名：Journal of Physics and Chemistry of Solids
• 出版年：April, 2014
• 年：2014
• 卷：75
• 期：4
• 页码：558-569
• 全文大小：2797 K

文摘

We present the structural, cation distribution, electrical and magnetic studies of CoAl_xFe_2鈭?em>xO₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8) ferrites. The Rietveld-fitted X-ray diffraction (XRD) patterns confirm the formation of single-phase cubic spinel structures with space group for all the samples. A comprehensive analysis of XRD-based cation distribution has been performed to see the effect of Al³⁺ ions substitution on various structural parameters such as site ionic radii, edge length, bond length and interionic distances. The dielectric constant and direct current (DC) conductivity decreases with increasing Al³⁺ substitution up to x = 0.4. However, with further increase in Al³⁺ substitution, both the dielectric constant and the DC conductivity increase. The presentation of dielectric data in the complex electric modulus form reveals the presence of a non-Debye-type relaxation behaviour in the considered ferrites. The power law behaviour of alternating current (AC) conductivity indicates a strong correlation among electrons in these systems. The isothermal magnetisation versus applied field curves with high-field slope and significant coercivity suggest that the studied materials are highly anisotropic with canted spin structures. The samples exhibit ferrimagnetic behaviour at 300 K and the magnetisation decreases with increasing Al³⁺ concentration. The as-prepared samples are promising candidates for various industrial applications.