Effects of structural disorder in lithium manganite and titanate oxides |
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Authors: | Yu G Chukalkin A E Teplykh D G Kellerman and V S Gorshkov |
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Institution: | (1) Condensed Matter Physics Laboratory, The Vinca Institute, P.O. Box 522, 11001 Belgrade, Serbia;(2) Institute of Experimental Physics, Slovak Academy of Sciences, 04001 Kosice, Slovak Republic |
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Abstract: | The structures and magnetic states of stoichiometric lithium manganite LiMn2O4 and manganites and titanates Li1.33Mn1.67O4 and Li1.33Ti1.67O4 with excess lithium in both the initial (as-synthesized) state and after irradiation by fast (E
eff ≥ 1 MeV) neutrons with a fluence of 2 × 1020 cm−2 have been studied using neutron diffraction, X-ray diffraction, and magnetic methods. It has been established that the irradiation
brings about a noticeable redistribution of manganese, titanium, and lithium cations over nonequivalent tetrahedral (8a) and octahedral (16d) positions of a spinel lattice. This structural disorder causes a radical change in the physical properties of the materials
under study. The charge order existing in the initial LiMn2O4 sample is destroyed. There arises a strong intersublattice indirect exchange interaction Mn(8a)-O-Mn(16d). The disorder is accompanied by the antiferromagnet-ferrimagnet (LiMn2O4) and paramagnet-ferrimagnet (Li1.33Mn1.67O4) magnetic transitions. |
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