Exploration of formation conditions of ternary all-hydrido phosphates at gigapascal pressures

Recently it has been shown that high pressure (gigapascal) hydrogenations can afford novel semiconducting hydridosilicate compounds – such as K2SiH6, Na3SiH7, and BaSiH6 – featuring octahedral [SiH6]2- species in which Si attains a hypervalent bonding situation. The emerging family of hydridosilicates suggests that also the isoelectronic hydridophosphates (featuring hypervalent [PH6]-) with potentially interesting properties may exist and become accessible from gigapascal hydrogenations. Here we propose to perform in situ synchrotron diffraction studies of reaction mixtures AH + P + H2 (A = K, Cs) and KP + H2 at pressures up to 12 GPa using ID06-LVP at the ESRF. The aim is to exploit the well-controlled p, T environment in large volume press experiments – in combination with angle-dispersive diffraction – to unfold formation conditions and phase relations of ternary phosphorous hydrides A–P–H as well as to elucidate their structures.