The pressure response of Prussian white

Prussian white, Na2Fe[Fe(CN)6]·nH2O, is an interesting material both fundamentally and from an applied perspective. The cyanide-based double perovskite structure has a complex phase behaviour dictated by both temperature and the hydration state. A range of phase transitions arise from changes to the octahedral tilting, like for perovskites. Despite the technological interest in this material, its high-pressure behaviour has still not been investigated. By studying hydrated and dehydrated Prussian white with neutron diffraction under high pressure, we will elucidate the phase transitions, determine the bulk modulus and explore the possibility of pressure-induced spin crossover. Unlike temperature, compression is decoupled from changes in the hydration state, which will allow detailed studies of the hydrated state. In summary, there are many reasons why investigating the high-pressure behaviour of Prussian white is worthwile. Our study will give fundamental insights into the structural behaviour and will be useful for future applications with the material.