Mn-substituted spinel Li4Ti5O12 materials studied by multifrequency EPR spectroscopy

摘要

In this contribution we report on the influence of Mn doping on various physical properties of Li4Ti_(5-x)Mn_xO_(12) (x = 0, 0,005, 0.025, 0.01, 0.05, 0.075, 0.1 and 0.2). Spinel-type (space group Fd3m, a = 0.8358 nm) Li4Ti_(5-x)Mn_xO_(12 )was produced as highly uniform and polyhedral shaped powder in a size range between 200 and 400 nm. The crystal structure of Li4Ti_(5-x)Mn_xO_(12), the morphology and the Mnion distribution have been investigated by X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). The oxidation state of Mn and the conductivity behavior of Mnsubstituted Li4Ti_(5-x)Mn_xO_(12) samples have been studied using multi-frequency electron paramagnetic resonance (EPR). Mn is incorporated as Mn~(2+), and these ions increase the conductivity of Li4Ti_(5-x)Mn_xO_(12) a conductivity value of 0.48 x 10~(-8) S cm`(-1) was measured for Li4Ti_(5-x)Mn_xO_(12) withx = 0.075, which is tenfold larger than that of undoped Li4Ti_(5-x)Mn_xO_(12).