Cooling by adiabatic (DE)pressurization - the barocaloric effect

Abstract

The barocaloric effect reflects a new cooling principle at low temperatures without the need of liquefied gases nor magnetic fields as used in other cooling techniques. A pressure induced structural and/or magnetic phase transition is used to obtain a significant change in the system's entropy which leads to its cooling if done adiabatically. The effect is illustrated for the two rare earth compounds Pr₁ − _xLa_xNio₃ and Ce_x(La,Y)₁ − _xSb using a structural and a magnetic phase transition, respectively. In situ experiments on Ce_x(La,Y)₁−_xSb are presented and reveal a cooling rate of up to 2 K per 0·5 GPa pressure change at working temperatures below 20 K for x=1 and up to 0·42 K per 0·24 GPa for x=0·85 at around 10K.

Key Words:

• Adiabatic cooling
• Pressure-induced phase transitions
• Crystal fields
• High pressure
• Magnetoelastic effects
• Magnetic order