Jahn-Teller distortion in manganites

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Jahn-Teller distortion in manganites
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Mn
La, Pr
oxygen
La3Mn3O32-
3
Mn
La, Pr
oxygen
La3Mn3O32-
4
MnO6 octahedron
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25Mn 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d5
Mn3 1s2, 2s2, 2p6, 3s2, 3p6
, 3d4
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2p
Different Mn d-orbitals have diferrent overlaps
with the oxygen p-orbital.
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Mn3
Eexch (Hunds rule)
Different Mn d-orbitals have diferrent overlaps
with the oxygen p-orbital.
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5
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Jahn-Teller distortion The total energy is
minimized by distorting the cubic unit cell. The
degeneracy of the eg levels is removed by the
crystal field of the distorted unit cell. The
single eg electron can then be at a lower energy
compared to the cubic unit cell. Hence the Mn3
ion induces a Jahn-Teller distortion in the
crystal. An Mn4 ion will not induce J-T
distortion because there is no eg electron.
Mn3
EJT
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