Magnetocaloric effect, magnetotransport and magnetic properties of polycrystalline Pr(0.65-x)GdxSr0.35MnO3 (x ≤ 0.3) compounds

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Journal of Magnetism and Magnetic Materials Pub Date : 2024-10-23 DOI:10.1016/j.jmmm.2024.172605

Roman Atanasov, Marc du Plessis, Razvan Hirian, Rares Bortnic, Gabriela Souca, Iosif Grigore Deac

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Abstract

Polycrystalline Pr_0.65-xGd_xSr_0.35MnO₃ (x = 0.01, 0.05, 0.1, 0.2, 0.3) manganites were prepared by conventional solid-state method. Structural analysis has revealed a change in structure with x = 0.2, from Rhombohedral (R-3c) to Orthorhombic (Pbnm) symmetry. Small oxygen deficiency was found in the samples. The electrical measurements revealed typical colossal magnetoresistance (CMR) behavior, with single metal–insulator peak at T_p for all investigated samples. The small polaron hopping (SPH) and variable-range hopping (VRH) models were used to describe the electrical conduction above T_p. Magnetic measurements show an increase in magnetization below the Curie temperature, T_C. Values of T_c diminish with increasing Gd³⁺ content. Isothermal measurements around critical points suggest a possible interaction between the 4f-ions and Mn-sublattice The magnetic critical behavior analysis established the tri-critical mean-field model to be the governing model for the series. Large magnetic entropy change ΔS_M at near room temperature (278 K) was exhibited by the x = 0.01 sample at 2.2 J/kgK in μ₀ΔH = 1 T and 5.36 J/kgK in μ₀ΔH = 4 T. The largest |ΔS_M| value was shown by the x = 0.1 sample. The values of the relative cooling power (RCP) and the temperature-averaged entropy change (TEC) increased with substitution qualifying these compounds as magnetocaloric materials.

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多晶 Pr(0.65-x)GdxSr0.35MnO3 (x ≤ 0.3) 复合物的磁ocaloric 效应、磁传输和磁特性

采用传统固态法制备了多晶 Pr0.65-xGdxSr0.35MnO3 (x = 0.01, 0.05, 0.1, 0.2, 0.3) 锰矿。结构分析表明，当 x = 0.2 时，结构发生了变化，从斜方体（R-3c）对称变为正方体（Pbnm）对称。在样品中发现了少量缺氧现象。电学测量显示了典型的巨磁阻（CMR）行为，所有研究样品在 Tp 时都有单一的金属-绝缘体峰值。小极子跳变（SPH）和可变范围跳变（VRH）模型用于描述 Tp 以上的电导。磁性测量结果表明，在居里温度（TC）以下磁化会增加。Tc 值随着 Gd3+ 含量的增加而减小。临界点附近的等温测量结果表明，4f 离子和锰亚晶格之间可能存在相互作用。x = 0.01 样品在接近室温（278 K）时表现出较大的磁熵变化 ΔSM，μ0ΔH = 1 T 时为 2.2 J/kgK，μ0ΔH = 4 T 时为 5.36 J/kgK。相对冷却功率（RCP）和温均熵变（TEC）值随着这些化合物被替换为磁致性材料而增加。

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来源期刊

Journal of Magnetism and Magnetic Materials 物理-材料科学：综合

CiteScore

5.30

自引率

11.10%

发文量

1149

审稿时长

59 days

期刊介绍： The Journal of Magnetism and Magnetic Materials provides an important forum for the disclosure and discussion of original contributions covering the whole spectrum of topics, from basic magnetism to the technology and applications of magnetic materials. The journal encourages greater interaction between the basic and applied sub-disciplines of magnetism with comprehensive review articles, in addition to full-length contributions. In addition, other categories of contributions are welcome, including Critical Focused issues, Current Perspectives and Outreach to the General Public. Main Categories: Full-length articles: Technically original research documents that report results of value to the communities that comprise the journal audience. The link between chemical, structural and microstructural properties on the one hand and magnetic properties on the other hand are encouraged. In addition to general topics covering all areas of magnetism and magnetic materials, the full-length articles also include three sub-sections, focusing on Nanomagnetism, Spintronics and Applications. The sub-section on Nanomagnetism contains articles on magnetic nanoparticles, nanowires, thin films, 2D materials and other nanoscale magnetic materials and their applications. The sub-section on Spintronics contains articles on magnetoresistance, magnetoimpedance, magneto-optical phenomena, Micro-Electro-Mechanical Systems (MEMS), and other topics related to spin current control and magneto-transport phenomena. The sub-section on Applications display papers that focus on applications of magnetic materials. The applications need to show a connection to magnetism. Review articles: Review articles organize, clarify, and summarize existing major works in the areas covered by the Journal and provide comprehensive citations to the full spectrum of relevant literature.