The first studies of KH ₂ PO₄ by neutron diffraction

Abstract

The early measurements with neutrons established that at 77K, in the ferroelectric state, the hydrogen atoms were in ordered positions at a distance of 1.05 Å from the oxygens. Above the transition temperature this order is destroyed; the hydrogens are probably distributed randomly between pairs of positions, but this could not be established conclusively and anisotropic centred hydrogens remained a possibility.