Refinement of hydrogen positions in Phase II of β-LiNH4SO4

The atomic positions and thermal parameters of the crystal structure for phase II of β-LiNH4SO4 are determined from single crystal neutron diffractiondata at room temperature to refine N-H bond lengthsfor ammonium ions. The neutron data are collected using an E5 diffractometerin BENSC (HMI, Berlin, Germany). Atomic positions and thermal parameters are determined by the least-squares method up to R = 0.072 and wR = 0.057. It is shown that an ammonium ion polyhedronis the regular tetrahedron.