Poster: Ferroelectricity in H-bonded H2CsPO4 (CDP) studied by ab initio calculations

J LASAVE; P ABUFAGER; S KOVAL

Porto

Conferencia; EMF- 13th European Meeting on Ferroelectricity; 2015

Universidad de Porto - Comite internacional de Ferroelectricidad

Cesium dihydrogen phosphate (CsH2PO4 (or CDP))  is a solid acid compound that belongs to a large famil of H-bonded ferroelectrics whose prominent member is  KH2PO4  (KDP). It displays a quasi 1D FE phase transition at atmospheric pressure which differs from the 3D nature of the FE ordering observed in KDP. The paraelectric-ferroelectric (PE-FE) phase transition in CP arises at a critical temperature Tc  of 150K.  There is a huge isotope effect in the PE-FE transition of CDP with a Tc increase of  110K for the deuterated compound CsD2PO4  (DCDP).The microscopic mechanism of the FE transition remains unclear and  also the magnitude of the spontaneous Polarization Ps, comparable to KDP? s Ps,  despite of the different  number of protons involved in the transition. Ab Initio methods, first validated extensively, we study this features and  also determined the internal parameteres for CDP and DCDP  We also investigate  relevant excitations measured in the PE phase which are relevant for the FE transition.