Applications to metal oxides and other inorganic solids
Phillips and Williams gave some general guidelines to determine whether good overlap would occur. A d band formation is likely to occur if:
(1) The formal charge
of the cations is small.
(2) The cation occurs
early in the transition series.
(3) The cation is in
the 2nd or 3rd transition series.
(4) The anion
is reasonably electropositive.
Effects (1) to (3) are involved in keeping the d orbitals spread out to reduce the amount of positive charge they feel from the parebt ion.
Effect (4) is associated with reducing ionicity and the band gap as previously discussed on page 18.
|Page 20 of 25|