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<p>A comprehensive investigation of the structural, magnetic, and magnetocaloric properties of polycrystalline La<sub>0.67−<i>x</i></sub>Gd<sub><i>x</i></sub>Ca<sub>0.33</sub>MnO<sub>3</sub> (<i>x</i> = 0, 0.05, 0.1, 0.15, and 0.2), synthesized by the solid-state method, has been carried out. X-ray diffraction confirmed that all compositions crystallize in a single-phase orthorhombic <i>Pbnm</i> structure. A systematic decrease in the Curie temperature, from 257&#xa0;K (<i>x</i> = 0) to 61&#xa0;K (<i>x</i> = 0.2), was observed and attributed to the suppression of double-exchange interactions and the emergence of magnetic inhomogeneity. Most notably, the substitution of Gd led to a pronounced enhancement in the magnetic entropy change (|Δ<i>S</i><sub><i>M</i></sub>|), reaching a maximum of 11.24&#xa0;J/kg&#xa0;K under a 5&#xa0;T field for the <i>x</i> = 0.2 composition, which stands as one of the highest values reported for manganites. In addition, a secondary anomaly in the entropy change curves, particularly at elevated fields, was associated with a field-induced metamagnetic transition arising from the coexistence of paramagnetic and antiferromagnetic states above <i>T</i><sub><i>C</i></sub>. Critical behavior analysis based on Arrott plots further revealed that all samples exhibit a first-order magnetic phase transition. These simultaneous observations of exceptionally large Δ<i>S</i><sub><i>M</i></sub> values and metamagnetic features highlight the potential of these rare-earth-modified manganites for high-performance magnetocaloric applications.</p>

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Impact of Gd Substitution on the Structure, Magnetic Ordering, and Magnetocaloric Response of La0.67Ca0.33MnO3

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • O. F. Seker,
  • T. Izgi,
  • V. S. Kolat,
  • N. Bayri,
  • H. Gencer,
  • M. Pektas Kolat,
  • S. Atalay

摘要

A comprehensive investigation of the structural, magnetic, and magnetocaloric properties of polycrystalline La0.67−xGdxCa0.33MnO3 (x = 0, 0.05, 0.1, 0.15, and 0.2), synthesized by the solid-state method, has been carried out. X-ray diffraction confirmed that all compositions crystallize in a single-phase orthorhombic Pbnm structure. A systematic decrease in the Curie temperature, from 257 K (x = 0) to 61 K (x = 0.2), was observed and attributed to the suppression of double-exchange interactions and the emergence of magnetic inhomogeneity. Most notably, the substitution of Gd led to a pronounced enhancement in the magnetic entropy change (|ΔSM|), reaching a maximum of 11.24 J/kg K under a 5 T field for the x = 0.2 composition, which stands as one of the highest values reported for manganites. In addition, a secondary anomaly in the entropy change curves, particularly at elevated fields, was associated with a field-induced metamagnetic transition arising from the coexistence of paramagnetic and antiferromagnetic states above TC. Critical behavior analysis based on Arrott plots further revealed that all samples exhibit a first-order magnetic phase transition. These simultaneous observations of exceptionally large ΔSM values and metamagnetic features highlight the potential of these rare-earth-modified manganites for high-performance magnetocaloric applications.