High-pressure structural studies of MOH layered compounds (M=Na, K, Rb, Cs)

The structures of alkali metal (Na, K, Rb, Cs) hydroxides were investigated using energy-dispersive X-ray diffraction at pressures up to 20 GPa. The phase transitions previously discovered with optical methods (by Krobok and co-authors in 1992 and 1994) are confirmed. A structure is proposed for the high-pressure phases of KOH and RbOH, and for a predicted phase of CsOH. Equation of state parameters are presented for the phases encountered