Electronic structure of cubic Li(Fe0.1Mn1.9)O4 studied with Mossbauer spectroscopy and first-principles calculation

Mossbauer spectrum was collected in Fe3+ doped cubic LiMn2O4 (LiFe0.1Mn1.9O4) by using Fe-57 as the radiation source. In the model of the crystal-field theory, the energy gaps between different d orbitals, DeltaE(b(1g)-a(1g)) and DeltaE(b(2g)-e(g)), characterize the strength of the Jahn-Teller effect in the crystal. A relationship between the Mossbauer quardrupole splitting and the energy gaps was established, based on which both DeltaE(b(1g)-a(1g)) and DeltaE(b(2g)-e(g)) of the [MnO6] octahedron in LiFe0.1Mn1.9O4 are estimated to be about 0.41 and 0.30 eV, respectively. Electronic structure of LiMn2O4 was studied theoretically via ab initio calculation based on the density-functional theory. Calculation shows that a gap about 0.28 eV between the filled Mn d bands is equivalent to DeltaE(b(2g)-e(g)). It also shows that the first unoccupied states are dominated by Mn 3d contribution essentially from both a(1g) and b(1g) of Mn d states. Distance between the two peaks in the first unoccupied band was used to calculate DeltaE(b(1g)-a(1g)), which is about 0.36 eV. The Mossbauer quardrupole splitting characterizes Jahn-Teller distortion and its effect on the fine structure of Mn 3d bands. (C) 2003 American Institute of Physics.