Application of the through-bond correlation NMR experiment to the characterization of crystalline and disordered phosphates

Through-bond correlation NMR experiments have been used to characterize the structure of MP2O7 crystalline compounds and disordered phosphates. For MP2O7 materials, the refocused INADEQUATE experiment allows discrimination between the possible space group symmetries of the room temperature structure. The results show that the room temperature structure of ZrP2O7 adopts Pbca symmetry. For lead phosphate glasses, the refocused INADEQUATE experiment can be used to determine the P-O-P through-bond connectivities between the different types of PO4 tetrahedra. In these glasses, a correlation between the distributions of J-couplings and (31)p isotropic chemical shifts is shown by using the 2D J-resolved experiment. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.