Neutron scattering

Physics

Meteorology

Relaxation (psychology)

Deuterium

Crystallography

Crystal structure

Crystallite

Neutron

Psychology

Nuclear physics

Chemistry

Bar (unit)

Metallurgy

Materials science

Calorimetry

Condensed matter physics

Spin crossover

Superconductivity

Atmospheric temperature range

Transition temperature

Neutron diffraction

Social psychology

Thermodynamics

Advanced Materials

The first experimental evidence for a giant, conventional barocaloric effect (BCE) associated with a pressure-driven spin crossover transition near room temperature is provided. Magnetometry, neutron scattering, and calorimetry are used to explore the pressure dependence of the SCO phase transition in polycrystalline samples of protonated and partially deuterated [FeL2 ][BF4 ]2 [L = 2,6-di(pyrazol-1-yl)pyridine] at applied pressures of up to 120 MPa (1200 bar). The data indicate that, for a pressure change of only 0-300 bar (0-30 MPa), an adiabatic temperature change of 3 K is observed at 262 K or 257 K in the protonated and deuterated materials, respectively. This BCE is equivalent to the magnetocaloric effect (MCE) observed in gadolinium in a magnetic field change of 0-1 Tesla. The work confirms recent predictions that giant, conventional BCEs will be found in a wide range of SCO compounds.

Giant Barocaloric Effect at the Spin Crossover Transition of a Molecular Crystal