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 (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\left|\Delta {S}_{{\rm{it}},{\rm{rev}}}\right|$</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close="∣" open="∣"> <mrow> <mi mathvariant="normal">Δ</mi> <msub> <mrow> <mi>S</mi> </mrow> <mrow> <mi mathvariant="normal">it</mi> <mo>,</mo> <mi mathvariant="normal">rev</mi> </mrow> </msub> </mrow> </mfenced> </math></EquationSource> </InlineEquation> = 13.4 J kg−1 K−1) and twenty-fold increase in operational temperature span (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\Delta {T}_{{\rm{span}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Δ</mi> <msub> <mrow> <mi>T</mi> </mrow> <mrow> <mi mathvariant="normal">span</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> = 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.

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

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2026年1月27日

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Frederic Rendell-Bhatti,
Melony Dilshad,
Celine Beck,
Markus Appel,
Alba Prats,
Eamonn T. Connolly,
Claire Wilson,
Lewis Giannelli,
Pol Lloveras,
Xavier Moya,
David Boldrin,
Donald A. MacLaren

摘要

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 ( $\left|\Delta {S}_{{\rm{it}},{\rm{rev}}}\right|$ $∣Δ S_{it, rev}∣$ = 13.4 J kg⁻¹ K⁻¹) and twenty-fold increase in operational temperature span ( $\Delta {T}_{{\rm{span}}}$ $Δ T_{span}$ = 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.