SYNTHESIS AND THERMODYNAMIC PROPERTIES OF THE NEW MONODIMENSIONAL DIPHOSPHATES LiM1.5P2O7 (M 2+ = Co 2+ , Cu 2+ )

Two compounds in the series LiM1.5P2O7 (M 2+ = Co 2+ or Cu 2+ ) are isolated by solid phase and characterized by DRX and IR spectroscopy methods. The DRX spectra are similar and related to LiNi1.5P2O7. Using the Treor program, we found that both phases crystallize in a monoclinic system with P21/c space group. The magnetic susceptibility indicates the existence of an antiferromagnetic behavior at low temperature and specific heat measurements underline the low dimensionality (1D) of these pyrophosphates.