STRUCTURAL AND MAGNETIC FEATURES OF PYRO-PHOSPHATES USED AS LITHIUM INTERCALATION MATERIALS FOR NERGY STORAGE

摘要

The lithium pyrophosphates of divalent transition metals LiM_(1.5)P_2O_7 (M=Ni, Co, Mn, Cu) have been synthesized by a solid state reaction. The resulting powders were characterized using XRD, FTIR, Raman and SQUID magnetometer. Fingerprints of the P-O-P bridging bonds are observed in FTIR spectra which display an asymmetric stretching around 750 cm1. XRD data show that LiCo_(1.5)P_2O_7 is not isostructural with LiNi_(1.5)P_2O_7 but isomorph to α-CO2P2O7. Magnetic experiments exhibit the antiferromagnetic transition near T_N=11 K. The effective magnetic moment μ_(eff) of LiNi_(1.5)P_2O_7 and LiMn_(1.5)P_2O_7 compounds is in agreement for octahedral the Ni~(2+) and Mn~(2+)ions.