Neutron Diffraction Study of Ferrielectric Phase Transition in Monoclinic RbD<sub>2</sub>PO<sub>4</sub>
作者:Eisuke Magome、Masaru Komukae、Mitsuo Machida
DOI:10.1143/jpsj.76.044606
日期:2007.4.15
Crystal structures of monoclinic RbD2PO4 were studied at 297 K in the ferrielectric phase (phase III) and at 350 K in the paraelectric phase (phase II) by means of the single crystal neutron diffraction. The oxygen and deuterium atoms associated with the hydrogen bonds along the b axis are ordered in phase III and are disordered in phase II. Other atoms are ordered in both phases II and III. There are four kinds of PO4 tetrahedra in phase III. The ferri electricity of phase III were confirmed in the present neutron structural analysis. The III-II phase transition is caused by an order-disorder of PO4 tetrahedra accompanied by the motion of deuterium atoms within the hydrogen-bond chain. Fluctuations of the oxygen and deuterium atoms related hydrogen-bond chains along the b axis give rise to a quasi-one-dimensionality.