A Neutron Diffraction Study of the Ferroelectric Transition of CsH₂PO₄

Abstract

Hydrogen atoms in ferroelectric phase of CsH₂PO₄ have been located from low temperature neutron diffraction experiment. Chains of hydrogen bonds extending to both the crystallographic b- and c-axes are confirmed. The hydrogen atom in a shorter O–H··O bond becomes ordered at low temperature phase with bond length O–H=1.02 A auad H··O=1.46 A. Structural change below T_c shows that the hydrogen ordering accompanies a slight rotation of PO₄ tetrahedron about the one P–O bond.