Protonic conduction of polyhydrated phases obtained from colloidal dispersions of α-zirconium

Abstract

Highly dispersed and hydrated zirconium phosphate powders have been prepared by a procedure of sonication-lyophilization of colloidal dispersions of delaminated zirconium phosphate. The materials obtained have a layer structure of an α-type but form stable polyhydrated phases at room temperature. At 20°C the hydration water ranges from 1.2 to 3.5. mol/mol of Zr, for RH increasing from 5 to 90%; correspondingly the interlayer distance changes from 8.0 to 10.5 Å and the protonic conductivity at 20°C rises from 1.5×10 −6 to 3.0×10 −4 S cm −1. In the range 20/-20°C the activation energy for conduction increases from 5.3 to 12.1 kcal/mol for RH decreasing in the range 90-5%. A comparison of conductivities and activation energies with those previously determined for microcrystalline α-Zr(HOPO 3) 2·H 2O and pellicular zirconium phosphate in hydrogen form reveals that similar transport mechanisms occur in these materials.