Correlation Between Microstructural Evolution and Magnetocaloric Response in Suction-Cast MnCoGeB_0.02 Alloy.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Magnetism

Background:

• The magnetocaloric effect (MCE) is crucial for magnetic refrigeration technologies.
• Interactions between magnetic and structural transitions can enhance MCE, leading to giant or colossal effects.
• MnCoGe-based alloys are promising materials for MCE applications.

Purpose of the Study:

• To investigate the influence of microstructural variations on the magnetocaloric behavior of MnCoGeB$_{0.02}$ alloy.
• To understand the relationship between phase composition and magnetocaloric performance.
• To explore the impact of fabrication methods on MCE.

Main Methods:

• Fabrication of MnCoGeB$_{0.02}$ alloy samples using suction casting.
• Analysis of conical samples using X-ray diffraction to determine phase composition.
• Measurement of magnetic properties and magnetocaloric effect under a magnetic field change of 5.0 T.

Main Results:

• X-ray diffraction revealed a coexistence of hexagonal and orthorhombic phases within the samples.
• The proportion of these phases varied across different regions of the conical samples.
• Magnetic entropy change (|ΔS_Peak|) ranged from 12.3 to 6 Jkg^-1K^-1, demonstrating sensitivity to microstructural differences.

Conclusions:

• Microstructural variations, even subtle ones arising from solidification during suction casting, significantly affect MCE performance.
• Controlling the coexistence and proportion of hexagonal and orthorhombic phases is vital for optimizing magnetocaloric properties.
• These findings highlight the importance of microstructural control for developing advanced MnCoGe-based magnetocaloric materials.