Electron microscopy
  
Crystal Field Theory
- Practical Electron Microscopy and Database -
- An Online Book -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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The properties of transition-metal complexes can be predicted by the following theories:
        i) Valence-bond model.
        ii) Crystal field theory.
        iii) Ligand-field theory.

The heart of crystal field theory is splitting of d orbital energies and its consequences. Actually, crystal field theory has been extended to ligand field theory so that all the levels of covalent interactions can be incorporated into the model.

For perovskite cell structures, octahedral oxygen (O) bonding around the atom (Mn for LaMnO3 as shown in Figure 3140) in B-site generates the crystal field around the B-site atom. The valence states of the atoms (e.g. Mn) are fixed by charge neutrality. In the case of LaMnO3, if the parent compound is doped with Sr2+ for La3+, then Mn3+ (d3) is replaced by Mn4+ in the lattice.

Octahedral oxygen bonding around the Mn atom in LaMnO3

Figure 3140. Octahedral oxygen bonding around the Mn atom in LaMnO3.

 

 
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