In-situ Neutron Scattering as a Grand Opportunity for Caloric Materials Research: A Case Study of Colossal Barocaloric Effects

Abstract

Caloric materials are systems that exhibit significant thermal effects at phase transitions induced by external fields. They can be used for the solid-state refrigeration through a designated cooling cycle. Current caloric materials are characteristic of small isothermal entropy changes of about 50 J kg^-1K^-1, which is one of serious obstacles to the real applications. Recently, we have discovered that plastic crystals exhibit excellent barocaloric effects with typical entropy changes higher than 400 J kg^-1K^-1 induced by a small pressure. While these findings imply the solid-state refrigeration technologies based on caloric materials would be on the horizon, the underlying microscopic scenario on such colossal barocaloric effects has be established by employing in-situ pressure dependent neutron scattering measurements, which also serves as a confirmation of the new finding from the very fundamental origin. The present study might inspire to promote the application of neutron scattering techniques in the future caloric materials research.