Rotational dynamics in the ferroelectric and giant barocaloric (NH4)2SO4

Barocaloric materials, in which a large isothermal entropy change is associated with a pressure induced phase transition, offer an alternative to vapour-compression technologies that rely on refrigerants which contribute both to global warming and ozone depletion. Understanding the dynamics in barocalorics under pressure is clearly vital to explaining their properties. Recently it has been demonstrated that QENS has an important role to play in understanding the molecular dynamics in colossal barocaloric plastic crystals; and building on this we wish to add to our previous studies on the lattice dynamics in ammonium sulfate, to provide a complete picture of this commercially readily available barocaloric.