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<p>Polycrystalline Nd₀.₆Sr₀.₃Ba₀.₁MnO₃ manganite was synthesized via the auto-combustion method. Rietveld refinement confirmed an orthorhombic Pnma structure, while SEM and Williamson–Hall analysis revealed the nanocrystalline nature of the material. Magnetization measurements showed a second-order paramagnetic–ferromagnetic transition at Tc ≈ 90 K, with a deviation from the Curie–Weiss law above Tc, indicating the presence of a Griffiths phase. From a theoretical standpoint, the magnetic entropy change (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\Delta S}_{M}\)</EquationSource> </InlineEquation>) was evaluated using Maxwell relations, Landau theory, and the Hamad model, showing good agreement between the three approaches. A significant magnetocaloric effect (MCE) was observed near cryogenic temperatures, confirming the compound’s potential for magnetic refrigeration. Furthermore, the universal scaling of (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\Delta S}_{M}\)</EquationSource> </InlineEquation>) curves and the Banerjee criterion both confirmed the second-order nature of the transition. The critical exponents derived from isothermal magnetization and field-dependent (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({\Delta S}_{M}\)</EquationSource> </InlineEquation>) followed mean-field behavior, supporting the reliability of the critical analysis.</p>

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Auto-Combustion Synthesis and Cryogenic Magnetocaloric Performance of Ba-Substituted Nd–Sr-MnO₃ Nanoparticles

  • 期刊论文

  • 发表日期：

    2025年11月6日

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  • M. Jeddi,
  • E. Dhahri,
  • E. K. Hlil

摘要

Polycrystalline Nd₀.₆Sr₀.₃Ba₀.₁MnO₃ manganite was synthesized via the auto-combustion method. Rietveld refinement confirmed an orthorhombic Pnma structure, while SEM and Williamson–Hall analysis revealed the nanocrystalline nature of the material. Magnetization measurements showed a second-order paramagnetic–ferromagnetic transition at Tc ≈ 90 K, with a deviation from the Curie–Weiss law above Tc, indicating the presence of a Griffiths phase. From a theoretical standpoint, the magnetic entropy change ( \({\Delta S}_{M}\) ) was evaluated using Maxwell relations, Landau theory, and the Hamad model, showing good agreement between the three approaches. A significant magnetocaloric effect (MCE) was observed near cryogenic temperatures, confirming the compound’s potential for magnetic refrigeration. Furthermore, the universal scaling of ( \({\Delta S}_{M}\) ) curves and the Banerjee criterion both confirmed the second-order nature of the transition. The critical exponents derived from isothermal magnetization and field-dependent ( \({\Delta S}_{M}\) ) followed mean-field behavior, supporting the reliability of the critical analysis.