Controlling structural, magnetic and magnetocaloric properties of Pr0.6Sr0.35A0.05MnO3 through size variation

IF 2.8 3区物理与天体物理 Q2 PHYSICS, CONDENSED MATTER

Physica B-condensed Matter Pub Date : 2025-09-04 DOI:10.1016/j.physb.2025.417772

R. Thaljaoui , F. Khammassi , Abdullah Aljaafari

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引用次数: 0

Abstract

The influence of both particle size and monovalent cation doping (potassium (K), sodium (Na), and silver (Ag)) at the Sr sites on the structural, magnetic, and magnetocaloric properties of Pr_0.6Sr₀.₃₅A_0.05MnO₃ manganites, synthesized using the sol-gel (SG) method, has been examined. The compounds crystallize in an orthorhombic structure with the space group Pnma. Scanning Electron Microscopy (SEM) analysis revealed a variety of microstructures in the synthesized materials, ranging from micrometric to ultrafine grain sizes. Magnetic measurements as a function of temperature reveal a transition from paramagnetic (PM) to a ferromagnetic (FM) state at the Curie temperature T_C. The findings demonstrate a clear correlation between particle size and T_C, as particle size decreases, T_C decreases from 253.20 K to 231.23 K, significantly altering the magnetic properties of the material. Additionally, a decrease in particle size triggers the emergence of a Griffiths phase in the system, with the Griffiths phase percentage (%GP) increasing from 3.09 % to 15.97 %. To characterize the magnetic ordering associated with the PM-FM transition, Banerjee's criteria and Landau phase transition analysis were employed, both confirming second-order transitions. Under an applied magnetic field H = 2 T, the maximum magnetic entropy changes were measured as 1.37 J kg⁻¹ K⁻¹, 0.88 J kg⁻¹ K⁻¹, and 1.47 J kg⁻¹ K⁻¹ for Na, K and Ag-doped samples, respectively. Notably, the Pr_0.6Sr₀.₃₅Ag_0.05MnO₃ sample, with the smallest particle size of D_SEM = 0.001 μm, exhibits the highest relative cooling power (RCP) value of 102.12 J kg⁻¹ at 2 T. The magnetocaloric properties of the synthesized materials were further evaluated using performance metrics, such as refrigerant capacity (RC), temperature-averaged entropy change (TEC), and normalized refrigerant capacity (NRC). These results highlight the potential of these oxides for magnetic cooling technology.

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通过尺寸变化控制Pr0.6Sr0.35A0.05MnO3的结构、磁性和磁热性能

研究了溶胶-凝胶（SG）法合成的Pr0.6Sr0.35A0.05MnO3锰酸盐的结构、磁性和磁热学性能，以及在Sr位点上掺杂的一价阳离子(钾（K)、钠（Na）和银（Ag））和粒径对锰酸盐结构、磁性和磁热学性能的影响。化合物结晶成具有空间基团Pnma的正交结构。扫描电镜（SEM）分析显示，合成材料的微观结构从微米级到超细级不等。磁测量作为温度的函数揭示了从顺磁（PM）到铁磁（FM）状态在居里温度TC的转变。研究结果表明，粒径与TC之间存在明显的相关性，随着粒径的减小，TC从253.20 K减小到231.23 K，显著改变了材料的磁性能。此外，颗粒尺寸的减小会触发系统中Griffiths相的出现，Griffiths相百分比（%GP）从3.09%增加到15.97%。为了表征与PM-FM相变相关的磁有序，采用了Banerjee标准和Landau相变分析，两者都证实了二阶相变。在外加磁场H = 2t下，Na、K和ag掺杂样品的最大磁熵变化分别为1.37 J kg−1 K−1、0.88 J kg−1 K−1和1.47 J kg−1 K−1。值得注意的是，Pr0.6Sr0.35Ag0.05MnO3样品（最小粒径DSEM = 0.001 μm）在2 t下的相对冷却功率（RCP）值最高，为102.12 J kg−1。利用制冷剂容量（RC）、温度平均熵变（TEC）和标准化制冷剂容量（NRC）等性能指标进一步评价了合成材料的磁热性能。这些结果突出了这些氧化物在磁冷却技术中的潜力。

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来源期刊

Physica B-condensed Matter 物理-物理：凝聚态物理

CiteScore

4.90

自引率

7.10%

发文量

703

审稿时长

44 days

期刊介绍： Physica B: Condensed Matter comprises all condensed matter and material physics that involve theoretical, computational and experimental work. Papers should contain further developments and a proper discussion on the physics of experimental or theoretical results in one of the following areas: -Magnetism -Materials physics -Nanostructures and nanomaterials -Optics and optical materials -Quantum materials -Semiconductors -Strongly correlated systems -Superconductivity -Surfaces and interfaces