Engineering Light-Element Modified LaFe_11.6Si_1.4 Compounds Enables Tunable Giant Magnetocaloric Effect

Area of Science:

• Materials Science
• Solid-State Physics
• Thermodynamics

Background:

• Magnetocaloric refrigeration offers a promising alternative to traditional compression-based cooling.
• La(Fe,Si)₁₃-based materials are key candidates for practical magnetocaloric applications.
• Improving Curie temperature and tuning the giant magnetocaloric effect (GMCE) are crucial for development.

Purpose of the Study:

• To investigate the impact of light element (C, F, S) doping on the properties of LaFe_11.6Si_1.4 compounds.
• To explore strategies for enhancing Curie temperature (T_C) and achieving tunable GMCE.
• To understand the relationship between doping, microstructure, and magnetocaloric performance.

Main Methods:

• Systematic experimental investigation of light element (C, F, S) modified LaFe_11.6Si_1.4 compounds.
• Analysis of Curie temperature (T_C), thermal hysteresis, and magnetic entropy change (|Δ s_m|).
• Determination of dopant site occupancy, microstructural observation, and analysis of metastable atomic changes.

Main Results:

• All doped samples exhibited an increased T_C with minimal impact on thermal hysteresis.
• Fluorine doping maintained a significant GMCE, with a maximum magnetic entropy change of 19.2 J kg^-1 K^-1 at 2 T.
• Interstitial doping proved more effective for shifting T_C, but doping disrupted the first-order transition due to altered hybridization.

Conclusions:

• Interstitial doping is an effective strategy for increasing T_C in La(Fe,Si)₁₃ materials.
• The interplay between lattice pressure and covalent hybridization is critical for controlling magnetocaloric properties.
• Fluorine doping offers a viable route to maintain GMCE while enhancing T_C for advanced refrigeration.