A H-1-NMR RELAXATION-TIME STUDY OF DYNAMIC PROCESSES IN ZIRCONIUM-PHOSPHATES OF DIFFERING CRYSTALLINITIES AND IN RELATED-COMPOUNDS

The temperature dependences of the H-1 NMR relaxation times T1, T1rho and T2 are reponed for crystalline zirconium phosphate and for related compounds which also have the alpha-layered structure: zirconium phosphate (ZrP, Zr (HPO4)2 . H2O), zirconium phosphate phosphite (ZrPP, Zr(HPO3)1,2(HPO4)0.8.0.5H2O), pellicular zirconium phosphate (p-ZrP, Zr(HPO4)2.1.2H2O) and its ammonitated daughter compound ((NH4)1.8H0.2[Zr(PO4)2].0.8H2O). Variations in the forms of the temperature dependences are directly linked with variations in structure. In the ordered crystalline materials single minima in spin-lattice relaxation times (T1) are assigned as arising from 180-degrees-flips of interlamellar water molecules; in p-ZrP the disordered interlayer region results in a distribution of reorientational correlation times. Two minima in T1 are observed for each of p-ZrP and its ammoniated daughter compound; the higher temperature minimum arises from interlamellar species (H2O in p-ZrP and NH4+ in the ammonium compound) and the lower temperature minimum is assigned to those same species present in defects and having a consequent distribution of correlation times.