Periodic Reporting for period 4 - BCOOL (Barocaloric materials for energy-efficient solid-state cooling)
Reporting period: 2020-10-01 to 2022-09-30
I aim at developing new barocaloric materials by exploiting phase transitions in non-magnetic solids whose structural and thermal properties are strongly coupled. These materials are normally made from cheap abundant elements, and display very large latent heats and volume changes at structural phase transitions, which make them ideal candidates to exhibit extremely large barocaloric effects that outperform those observed in expensive barocaloric magnetic materials, and that match applications needs.
My unique approach combines i) materials science to identify materials with outstanding barocaloric performance, ii) advanced experimental techniques to explore and exploit these novel materials, iii) materials engineering to create new composite materials with enhanced barocaloric properties, and iv) fabrication of barocaloric devices, using insight gained from modelling of materials and device parameters. If successful, my ambitious strategy will culminate in revolutionary solid-state cooling devices that are environmentally friendly and energy efficient.
My research team has studied barocaloric effects in a number of non-magnetic solids that are made from cheap abundant elements. We found giant reversible barocaloric effects at room temperature that outperform those observed in the best barocaloric magnetic materials, and those predicted in inferior barocaloric ferroelectric oxides. Our exciting discoveries have led to a patent that has been filled by Cambridge Enterprise, and that has attracted attention across the largest refrigeration companies in Europe and the US.
In particular:
We found giant barocaloric effects driven using hydrostatic pressure in the superionic conductor silver iodide. Application of high pressure to this compound leads to the melting of the cation sublattice, yielding a large volume change and a large latent heat. The barocaloric performance in this compound varies only slowly on changing the operating temperature, as required for effective operation in prospective heat pumps. This work has led to a publication in Nature Communications [Nature Communications 8, 1851 (2017)].
We studied barocaloric effects in a number of hybrid organic-inorganic perovskites, via temperature and pressure dependent calorimetry and thermometry. These hybrid perovskites show giant barocaloric effects near room temperature, using order-of-magnitude smaller applied pressures than the magnetic materials, ferroelectric materials, and superionic conductors above. This work has led to a publication in Journal of Materials Chemistry C [Journal Materials Chemistry C 6, 9867 (2018)].