New phase transitions and superlattice formation in monoclinic RbD2PO4

A summary is given in this paper of the experimental results recently studied on the new successive phase transitions of RbD2PO4 by means of dielectric, X-ray diffraction and Raman scattering techniques. The crystal structure determined at room temperature demands ferrielectric character with a space group P21, being consistent with the appearance of small spontaneous polarization (−2×10−8 C/cm2) found below the lower transition. Raman scattering measurements indicate the existence of a soft optic mode associated with the upper transition.