7Li, 31P and 1H Static and MAS NMR investigations in the mixed crystals Li(1-x)(NH4)xH2PO4 (0.3 \leq x \leq 0.7)

Mixed crystals Li(1-x)(NH4)xH2PO4 (0.3 \leq x \leq 0.7) were grown over a wide range of composition from an aqueous solution and are studied by X-ray diffraction and NMR. The 7Li, 31P and 1H static and MAS NMR exhibit a marked composition dependence. Room temperature 7Li NMR spectra shows an increased motional narrowing with an increase of Li content indicating an overall increase in mobility of Li ions. The MAS spectrum exhibits a sharp peak with the resolution width which is consistent with the average of static dipolar interactions. All these observations clearly indicate that, at room temperature the transverse relaxation and the second order quodrupole interactions are negligible contributions in comparison with the static dipolar interaction. At high temperatures the central linewidth was drastically reduced corresponding to the averaging of zero dipolar interactions by motional narrowing. The results obtained on 7Li, 31P and 1H have been discussed in detail as a function of x as well as temperature