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<p>In this paper, La<sub>0.7</sub>Sr<sub>0.15</sub>Ca<sub>0.15</sub>Mn<sub>0.95</sub>A<sub>0.05</sub>O<sub>3</sub> (A = Fe, Co and Ni) were fabricated via the sol–gel (S-G) approach. The samples are all rhombohedral structure shapes and belong to the trigonal space group R-3c, as shown by XRD. ZEISS Gemini SEM 300 scans showed irregular sub-micron particles with decreasing particle size for La<sub>0.7</sub>Sr<sub>0.15</sub>Ca<sub>0.15</sub>Mn<sub>0.95</sub>A<sub>0.05</sub>O<sub>3</sub> (A = Fe, Co and Ni). The magnetic properties were characterized utilizing an MPMS, and the magnetocaloric effects (MCE) were further investigated. The investigations of La<sub>0.7</sub>Sr<sub>0.15</sub>Ca<sub>0.15</sub>Mn<sub>0.95</sub>A<sub>0.05</sub>O<sub>3</sub> (A = Fe, Co and Ni) found that their Curie temperatures (Tc) were 289.5&#xa0;K, 290.2&#xa0;K, and 300&#xa0;K, respectively. The maximum magnetic entropy change (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="339_2025_8622_Article_IEq1.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="65" /> </InlineMediaObject> <EquationSource Format="TEX">\(-\Delta {S}_{M}^{max}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mi mathvariant="normal">Δ</mi> <msubsup> <mi>S</mi> <mrow> <mi>M</mi> </mrow> <mrow> <mi mathvariant="italic">max</mi> </mrow> </msubsup> </mrow> </math></EquationSource> </InlineEquation>) for La<sub>0.7</sub>Sr<sub>0.15</sub>Ca<sub>0.15</sub>Mn<sub>0.95</sub>A<sub>0.05</sub>O<sub>3</sub> (A = Fe, Co and Ni) at 5&#xa0;T is 5.107&#xa0;J/(kg∙K), 4.177&#xa0;J/(kg∙K) and 3.852&#xa0;J/(kg∙K), and the relative cooling power (<i>RCP</i>) is 264.819&#xa0;J/kg, 275.3409&#xa0;J/kg and 288.7435&#xa0;J/kg. The Arrott curve, normalization and Curie–Weiss law (CW) fit together to determine that the second-order ferromagnetic-to-paramagnetic (FM-to-PM) transition is observed in the three samples, along with a small magnetic hysteresis and thermal hysteresis, the super-exchange interactions (SE) and the double-exchange interactions (DE) competed with each other to increase half peak width and <i>RCP</i>, with La<sub>0.7</sub>Sr<sub>0.15</sub>Ca<sub>0.15</sub>Mn<sub>0.95</sub>A<sub>0.05</sub>O<sub>3</sub> (A = Ni) having the largest <i>RCP</i>. While conventional low-temperature magnetic materials need to work in a liquid helium environment, room-temperature magnetic materials do not need to rely on extreme cooling conditions, which greatly reduces the cost of refrigeration equipment, and thus room-temperature magnetically cooled materials have a greater potential for research and development. In this paper, Ni is used as the doping element, and its <i>RCP</i> can reach 288.7435&#xa0;J/kg, and its Tc is close to room temperature, so it is possible to be used as a room-temperature magnetic cooling material.</p>

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Dopant-dependent spin–lattice coupling in La0.7Ca0.15Sr0.15MnO3: Fe/Co/Ni effects on magnetocaloric properties

  • 期刊论文

  • 发表日期：

    2025年5月27日

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  • Xiuxin Zheng,
  • Lin Gong,
  • Zhengguang Zou,
  • Zhuojia Xie

摘要

In this paper, La0.7Sr0.15Ca0.15Mn0.95A0.05O3 (A = Fe, Co and Ni) were fabricated via the sol–gel (S-G) approach. The samples are all rhombohedral structure shapes and belong to the trigonal space group R-3c, as shown by XRD. ZEISS Gemini SEM 300 scans showed irregular sub-micron particles with decreasing particle size for La0.7Sr0.15Ca0.15Mn0.95A0.05O3 (A = Fe, Co and Ni). The magnetic properties were characterized utilizing an MPMS, and the magnetocaloric effects (MCE) were further investigated. The investigations of La0.7Sr0.15Ca0.15Mn0.95A0.05O3 (A = Fe, Co and Ni) found that their Curie temperatures (Tc) were 289.5 K, 290.2 K, and 300 K, respectively. The maximum magnetic entropy change ( \(-\Delta {S}_{M}^{max}\) - Δ S M max ) for La0.7Sr0.15Ca0.15Mn0.95A0.05O3 (A = Fe, Co and Ni) at 5 T is 5.107 J/(kg∙K), 4.177 J/(kg∙K) and 3.852 J/(kg∙K), and the relative cooling power (RCP) is 264.819 J/kg, 275.3409 J/kg and 288.7435 J/kg. The Arrott curve, normalization and Curie–Weiss law (CW) fit together to determine that the second-order ferromagnetic-to-paramagnetic (FM-to-PM) transition is observed in the three samples, along with a small magnetic hysteresis and thermal hysteresis, the super-exchange interactions (SE) and the double-exchange interactions (DE) competed with each other to increase half peak width and RCP, with La0.7Sr0.15Ca0.15Mn0.95A0.05O3 (A = Ni) having the largest RCP. While conventional low-temperature magnetic materials need to work in a liquid helium environment, room-temperature magnetic materials do not need to rely on extreme cooling conditions, which greatly reduces the cost of refrigeration equipment, and thus room-temperature magnetically cooled materials have a greater potential for research and development. In this paper, Ni is used as the doping element, and its RCP can reach 288.7435 J/kg, and its Tc is close to room temperature, so it is possible to be used as a room-temperature magnetic cooling material.