Neutron scattering studies of phase transitions in protonated and deuterated ammonium hydrogen sulphate

The results of inelastic neutron scattering (INS) and neutron powder diffraction (NPD) of normal and deuterated ammonium hydrogen sulphate in different solid phases are presented. For the deuterated substance the high pressure phase IV can be obtained at atmospheric pressure upon heating of the ferroelectric phase II. It is shown that phase IV might exist in the temperature region of phases II and III even for a normal substance when the high pressure is reduced to atmospheric pressure.

Keywords:

• Ammonium hydrogen sulphate
• NH₄HSO₄
• neutron scattering
• phase transitions