STRUCTURAL AND MAGNETIC FEATURES OF PYRO-PHOSPHATESUSED AS LITHIUM INTERCALATION MATERIALS FOR ENERGYSTORAGE

摘要

The lithium pyrophosphates of divalent transition metals LiM_(1.5)P_20_7(M=Ni, Co, Mn, Cu) have been synthesized by a solid state reaction.The resulting powders were characterized using XRD, FILM, Ramanand SQUID magnetometer. Fingerprints of the P-O-P bridging bondsare observed in MR spectra which display an asymmetric stretchingaround 750 cm~(-1).XRD data show that LiCo_(1.5)P_20_7is not isostructuralwith LiNi_(1.5)P_20_7 but isomorph to a-Co_2P_20_7. Magnetic experimentsexhibit the antiferromagnetic transition near T_N=11K. The effectivemagnetic moment μ_(eff) of LiNi_(1.5)P_20_7and LiMn_(1.5)P_7compounds isin agreement for octahedral the Ni~(2+)and Mn~(2+)ions.