Magnetic properties of the chemically delithiated LixMn2O4 with 0.07≤x≤1

Magnetism for the LixMn2O4 samples with 0.07≤x≤1, which are prepared by a chemical reaction in HNO3 solution, is investigated by direct current susceptibility (χ) and muon-spin rotation/relaxation (μSR) measurements. The effective magnetic moment (μeff) of Mn ions decreases monotonically with decreasing x, indicating that Mn3+ ions with S  =2 (t2g3eg1) are oxidized to Mn4+ ions with S  =3/2 (t2g3) with decreasing x. On the other hand, as x decreases from 1 to 0.6, the Curie–Weiss temperature (Θp) increases monotonically from ∼−260 to −100 K, and then levels off to −100 K with further decreasing x. This indicates that the antiferromagnetic interaction is dominant in the whole x range. For the x=0.48 sample, the temperature dependence of χ in field-cooling mode clearly deviates from that in zero-field-cooling mode below ∼63 K (=Tm). Furthermore, the hysteresis loop is observed in the magnetization vs. field curve at 5 K. Since the zero-field μSR spectrum is well fitted by a strongly damped oscillation function, the Mn moments for the x=0.48 sample are in a highly disordered fashion down to the lowest temperature measured.

Magnetic phase diagram of the chemically delithiated spinel LixMn2O4 determined by magnetic susceptibility (χ) and muon spin rotation/relaxation (μSR) measurements. Figure optionsDownload as PowerPoint slideHighlights
► Magnetic properties of the chemically delithiated LixMn2O4 samples are investigated.
► The antiferromagnetic interaction is dominant in the whole x range.
► All the LixMn2O4 samples show a magnetic transition below Tm.
► The remanent magnetization vs. x curve exhibits a maximum at x=0.48.
► The x=0.48 sample is in a highly disordered magnetic state even at 1.8 K.