Enhanced reversible barocaloric effect at low pressure in neopentyl plastic crystal solid solutions

Abstract

The discovery of colossal barocaloric effects in neopentyl glycol (NPG) makes plastic crystals promising candidates for solid-state refrigerants with lower environmental impact than vapour compression fluids. Optimising operational temperatures and low-pressure operability remains challenging without compromising thermodynamic parameters. Here, we implement a strategy to improve the viability of NPG derivatives as barocaloric refrigerants. We blend pentaglycerine (PG) with NPG to lower the phase transition temperature, then dope the blend with 2% pentaerythritol (PE) to improve transition reversibility. In comparison with NPG under the same conditions, this ternary system has a seven-fold increase in reversible isothermal entropy change (|$\Delta S_{(it,rev)}$ | = 13.4 J kg${}^{-1}$ K${}^{-1}$) and twenty-fold increase in operational temperature span ($\Delta T_{span}$ = 18 K) at pressures of 1 kbar. Synchrotron x-ray diffraction and quasielastic neutron scattering reveal structural and dynamical effects that broaden the temperature range of the first-order phase transition due to intermolecular hydrogen bond network disruption by the molecular dopants. We propose that exploiting the compositional phase space of multi-component molecular blends is effective for designing practicable molecular BCs.

Manuscript: 23 pages, 7 figures. SI: 28 pages, 24 figures, 6 tables. SI follows main text

References in corpus (9)

• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Colossal barocaloric effects in plastic crystals
• Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol
• Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling
• Decoupled molecular and inorganic framework dynamics in CH${}_3$NH${}_3$PbCl${}_3$
• Dynamics in the ordered and disordered phases of barocaloric adamantane
• Pressure dependence of atomic dynamics in barocaloric ammonium sulfate: I. Rotations
• Direct observation of thermal hysteresis in the molecular dynamics of barocaloric neopentyl glycol
• Molecular origins of colossal barocaloric effects in plastic crystals