revealing structural mechanisms in high performing baracaloric materials via in situ temperature and pressure dependent x-ray diffraction

Barocaloric (BC) materials are solid state compounds that present large thermal changes related to solid-solid phase transitions induced by pressure. It is very important to understand the structural transitions that take place as a function of pressure from 1 bar to 1000 bar in these materials. Recently, a custom-made sample-cell developed at ESRF-SNBL showed that we are able to induce phase transitions in situ with pressure and access a new window into the dynamic structural changes occurring during BC transitions. In this proposal we will examine the dynamic structural changes occurring in situ under pressure and temperature of 6 different materials: [(CH3CH2CH2CH2)4N][M(N(CN)2)3] (M = Mn2+ or Cd2+) [1, 2], (C10H21NH3)2MnCl4 [3], (C9H19NH3)2MnCl4 [3], (NH4)2SO4 [4], and CH(NH2)2I [5], with some of the largest BC tunability and reversible entropy changes known. The measurements will determine key mechanisms dictating BC properties and help to tailor BC properties further.