Extreme barocaloric effect at dissolution

Extreme barocaloric effect at dissolution

Summary

Researchers demonstrate an extreme barocaloric cooling mechanism based on pressure‑controlled dissolution and precipitation of ammonium thiocyanate (NH4SCN) in water. Experiments (DSC, DTA, in situ temperature transfer, Raman, SXRD and optical microscopy) on concentrated solutions (notably 60 wt% NH4SCN) show immediate temperature changes on pressurisation/depressurisation, large dissolution enthalpies and entropy changes, and reversible fast kinetics compatible with a Carnot‑like pressure cycle. The team reports measurements under pressures up to ~600 MPa, observes peak shifting and merging with pressure (around 400 MPa), and presents thermodynamic modelling and device‑level discussion indicating high cooling capacity and potential low‑carbon advantages using a self‑circulating aqueous system.

Key Points

• Extreme barocaloric effect achieved by pressure‑tuned dissolution/precipitation of NH4SCN aqueous solutions (60 wt% highlighted).
• Response to pressure changes is effectively immediate; optical microscopy and in situ tests show rapid crystallisation/dissolution.
• Dissolution produces large enthalpy and entropy changes, yielding significant temperature transfer (ΔT) suitable for cooling cycles.
• Comprehensive characterisation: DSC/DTA, Raman spectroscopy, ambient and high‑pressure SXRD, and in situ ΔT transfer up to ~600 MPa.
• High‑pressure behaviour: thermal peaks shift to lower temperatures and merge with increasing pressure (noted at ~400 MPa), reflecting phase behaviour under compression.
• Authors propose a Carnot‑like pressure cycle and show favourable thermodynamic performance and practical advantages (direct heat transfer, self‑circulation, low‑carbon potential).
• Supplementary materials (videos, extended data tables/figures) document the mechanism and experimental details.

Context and relevance

This study contributes to the fast‑growing field of caloric and mechanocaloric materials as alternatives to vapour‑compression refrigeration and high‑GWP refrigerants. It connects to recent work on colossal barocaloric effects in plastic crystals, perovskites and n‑alkanes but is novel in exploiting liquid‑solid dissolution as the working change, combining large cooling capacity with very fast kinetics. For material scientists and engineers working on low‑carbon cooling technologies, the paper offers both foundational data and a plausible route to device concepts based on pressure‑driven dissolution cycles.

Why should I read this?

Quick take: if you’re into better fridges, heat pumps or cutting greenhouse gas‑heavy refrigerants, this is a neat trick worth a look. The team shows a salt‑in‑water dissolution cycle driven by pressure that gives big, fast temperature swings and looks surprisingly practical for compact, low‑carbon cooling devices. We did the skim for you — it’s clever and could matter.

Author style

Punchy — the paper pairs clear, thorough experiments with thermodynamic modelling. If you design cooling systems or study caloric materials, read the full paper: the experimental data and the proposed Carnot‑like cycle contain the detail needed to assess device feasibility.

Source

Article Date: 21 January 2026
Source: https://www.nature.com/articles/s41586-025-10013-1