Proton transport in KDP-family of ferroelectric materials

Abstract

Proton transport in potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) is briefly reviewed. The experimental results of Wagner's polarization measurement, coulometry, infrared spectroscopy, transient ionic current measurement, the variation of electrical conductivity with temperature and electrogravimetric analysis for KDP and ADP are reported. H+ and OH- ions are ascertained as the mobile ionic species. A new mechanism for the proton transport in KDP and ADP is suggested: A three-fold rotation of H2P4- units about any of the axes of PO4 tetrahedra leads to a configuration like O...H...H...O, the rearrangement of which provides H...O...H bridge that gets electrodissociated on the application of a d.c. electric field. © 1992 Indian Academy of Sciences.