Structural study of ND4Br at high pressure

A structure of ND4Br has been studied at pressures up to 9 GPa by means of time-of-flight neutron diffraction. A phase transition to the high pressure phase V was observed at P=8.2(5)GPa. It was found that the phase V has a t etragonal structure with an antiparallel ordering of ammonium ions, space g roup P4/nmm which is in strong resemblance with low temperature modificatio n ND4Br(II). Deuterium positional parameter as a function of pressure was o btained.