Temperature Dependence of Thermal Motion and Position of Hydrogen in Paraelectric KH₂AsO₄ Studied by Neutron Diffraction Structure Analysis

抄録

The temperature dependence of the mean-square thermal tensor of KH₂AsO₄ in the paraelectric phase has been investigated by neutron diffraction structure analysis. All the tensor elements except u₂₂(H) are extrapolated to zero and u₂₂(H) gives a positive intercept at 0 K. The temperature dependence of the H-site separation, δ, was obtained and was compared with that of KH₂PO₄. The result is well described by the order-disorder behavior of hydrogen.