Tunable Magnetocaloric Properties of Gd-Based Alloys by Adding Tb and Doping Fe Elements

Area of Science:

• Materials Science
• Thermodynamics
• Solid State Physics

Background:

• Magnetocaloric materials are crucial for efficient magnetic refrigeration technologies.
• Gadolinium-Terbium (Gd-Tb) alloys exhibit promising magnetocaloric properties.
• Optimizing alloy composition and processing is key to enhancing performance.

Purpose of the Study:

• To investigate the magnetocaloric properties of Gd-Tb alloys.
• To determine the optimal composition of Gd-Tb alloys for magnetic refrigeration.
• To explore the effects of Fe doping and heat treatment on alloy performance.

Main Methods:

• Synthesized and characterized Gd$_{1-x}$Tb$_x$ and (Gd$_{0.73}$Tb$_{0.27}$)$_{1-y}$Fe$_y$ alloys.
• Measured adiabatic temperature change (ΔT) via direct and indirect methods (up to 1.2 T).
• Evaluated isothermal magnetic entropy change (ΔS) and Curie temperature (T$_c$).

Main Results:

• Optimized composition identified as Gd$_{0.73}$Tb$_{0.27}$, exhibiting ~3.5 K ΔT at 1.2 T (T$_c$ = 276 K).
• Fe doping increased T$_c$ to 281 K while maintaining good magnetocaloric effect.
• Heat treatment at 1073 K for 10 h further improved ΔT by ~0.3 K and slightly increased T$_c$.

Conclusions:

• Gd$_{0.73}$Tb$_{0.27}$ alloys with Fe doping and optimized heat treatment show significant potential for magnetic refrigeration.
• The study demonstrates a method for tuning the Curie temperature of magnetocaloric materials.
• These findings are significant for developing advanced magnetic refrigeration systems operating under low magnetic fields.