Theoretical Study of Electronic Polarizabilities and the Spontaneous Polarization of the Compound RbH2PO4(RbDP) in the Orthorhombic-Ferroelectric Phase

The RbH(2)PO(4) (often abbreviated as RbDP) is an hydrogen bonded material, it crystallizes in the tetragonal system at room temperature, this phase belongs to the non-centrosymmetrical space group I (4) over bar 2d; therefore, it is piezoelectric. A transition occurs at 146 K into a ferroelectric phase with othorhombic symmetry and space group Fdd2. The polar axis lies along the direction of the c axis of the tetragonal phase.In this work, we discussed the ferroelectricity of RbDP on the basis of the dipole interaction among the constituent ions and we calculated quantitatively the effective charges of the different ions by taking into account of the experimental value of the spontaneous polarization. The results of the calculations point out the important role of the hydrogen-bonds.