Investigating nucleation-driven phase transitions in neopentyl molecular crystals using infrared thermography and polarised light microscopy

TL;DR

This study uses infrared thermography and polarised light microscopy to analyze phase transition kinetics in neopentyl glycol crystals, revealing how doping reduces supercooling and hysteresis for better cooling applications.

Contribution

It introduces combined imaging techniques to correlate microstructural disorder with phase transition behavior in barocaloric materials.

Findings

Doped NPG exhibits reduced supercooling and hysteresis.

Microstructural disorder increases nucleation events.

Imaging methods link local heat flow with bulk thermodynamics.

Abstract

Sustainable solid-state refrigerants based on barocaloric materials are often limited by thermal hysteresis associated with supercooling effects. Here, we present imaging methods to investigate and compare thermal behaviour and transition kinetics of the barocaloric molecular crystal neopentyl glycol (NPG) with those of a lightly doped derivative, NPG$_{0.99}$PE$_{0.01}$, which incorporates 1 mol % pentaerythritol (PE). We use temperature-dependent polarised light (PL) microscopy and infrared (IR) thermography to correlate phase transition kinetics and local heat-flow with the bulk thermodynamic response obtained from calorimetry. We show that the doped system exhibits reduced supercooling and thermal hysteresis, attributed to increased microstructural disorder and an increase in the number of nucleation events. These findings provide insight into the design of low-hysteresis barocaloric materials for high-efficiency solid-state cooling applications.