The Dynamics of Pressure Driven Phase Transitions: A Look into the Future of Solid-State Refrigeration
Claire Hobday a
a Department of Chemistry, University of Edinburgh, UK., United Kingdom
Proceedings of Dynamic Materials, Crystals and Phenomena Conference (DynaMIC23)
Fribourg, Switzerland, 2023 March 22nd - 24th
Organizers: Jovana Milic and Simon Krause
Invited Speaker, Claire Hobday, presentation 017
Publication date: 15th February 2023

Heating and cooling processes are responsible for 78% of the UK’s environmentally damaging fluorinated gas emissions, primarily due to the employment of hydrofluorocarbon (HFC)-based refrigerant gases.[1] Such compounds are being phased out due to their devastating environmental impact, notably very high global warming potentials (GWP) (~2000 times that of CO2). This has created a major technological and scientific challenge to find new types of refrigeration materials which are made from sustainable resources, have increased efficiency and are environmentally friendly throughout their entire lifecycle. There is now a strong focus on developing solid-state materials, which are easier to recycle, that demonstrate caloric effects. These have been shown to out-perform vapour compression technology in domestic refrigeration, additionally resulting in lower energy costs.[2] Caloric effects rely on the reversible thermal response of solids to an externally applied field (magnetic or electric field, or hydrostatic pressure) to give rise to magnetocaloric (MC), electrocaloric (EC) or barocaloric (BC) materials.

This talk focusses on understanding the barocaloric effect via study of order-disorder transitions in organic ionic plastic crystals (OIPCs). OIPCs provide a rich parameter space in which to explore the tunability of the BC effect experimentally. This class of materials are comprised completely of ions and at room temperature are solids with significant disorder in the crystal lattice.[3] The disorder comes from the rotational, translational and conformational motions which allows them to flow under stress and increases their conductivity, which has rendered them desirable solid-state electrolytes that can be used in batteries, fuel cells and solar cells.[4] OIPC’s inherent order-disorder phase change properties are ideal as potential candidates for BC refrigerants; however, little is known about how to maximise their ionic conductivity, ability to flow and change phase. This talk describes the use of high-pressure DSC and in-situ crystallographic studies under pressure and temperature to understand the reversibility of the process and the cyclability of the materials.

We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info