PROTONIC CONDUCTIVITY OF LAYERED ZIRCONIUM PHOSPHONATES CONTAINING -SO3H GROUPS .1. PREPARATION AND CHARACTERIZATION OF A MIXED ZIRCONIUM PHOSPHONATE OF COMPOSITION ZR(O3PR)0.73(O3PR')1.27.NH2O, WITH R = -C6H4-SO3H AND R' = -CH2-OH

A zirconium phosphonate of formula: Zr(O3P-C6H4-SO3H)0.73(O3P-CH2-OH)1.27.nH2O was prepared and characterized by X-ray powder diffraction, thermogravimetric analysis, EMF and ac conductivity measurements. The compound seems to have a layer structure of alpha-type and the number of water molecules in the interlayer region strongly depends on relative humidity so that hydrated phases with different interlayer distances are formed. EMF measurements showed the absence of electronic conduction. Both the conductivity and the parameters of the Arrhenius equation are strongly influenced by the water content. At 20-degrees-C and 90% relative humidity (n = 7.5) a conductivity of 1.6 x 10(-2) S cm-1, with an activation energy of 4.5 kcal/mol, was found. A correlation between changes in activation energy and interlayer distance was observed indicating the possible presence of a non-negligible component of bulk transport.