Magnetic refrigeration material operating at a full temperature range required for hydrogen liquefaction

Area of Science:

• Materials Science
• Thermodynamics
• Cryogenics

Background:

• Magnetic refrigeration (MR) is a promising alternative to gas compression for hydrogen liquefaction.
• Current MR materials lack sufficient magnetic entropy change (MCE) over the broad temperature range (20-77 K) needed for hydrogen liquefaction.
• Magneto-structural phase transitions in existing materials can degrade MCE performance and limit reusability.

Purpose of the Study:

• To develop novel MR materials with a giant MCE suitable for the full temperature range of hydrogen liquefaction.
• To achieve a reversible MCE in these materials for sustainable and practical MR cooling applications.
• To enable the use of MR technology for efficient hydrogen liquefaction, supporting the future green fuel economy.

Main Methods:

• Synthesis and characterization of Er(Ho)Co2-based compounds.
• Measurement of magnetic entropy change (-∆Sm) across the target temperature range (20-77 K).
• Analysis of phase transitions to ensure MCE reversibility and material stability.

Main Results:

• Er(Ho)Co2-based compounds exhibit a giant MCE (-∆Sm > 0.2 J cm⁻³K⁻¹) within the 20-77 K range.
• The MCE was demonstrated to be reversible by suppressing the detrimental magneto-structural phase transition.
• These materials show significant potential for practical MR cooling systems in hydrogen liquefaction.

Conclusions:

• Er(Ho)Co2-based alloys represent a breakthrough in MR materials for hydrogen liquefaction.
• The achievement of a giant, reversible MCE addresses key limitations of current MR technology.
• This advancement paves the way for efficient and sustainable hydrogen liquefaction using magnetic refrigeration.