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Valency and oxidation state in PbTiO3

  1. Oct 28, 2009 #1
    I have two related questions on PbTiO3 perovskite structure and chemical environment.

    The Pb K-egde Xanes data reveals that Pb is in a mixed valence state of Pb4+ and Pb2+. However in literature Pb is claimed to be in Pb2+ state. The Pb 6s2 electrons hybridize with the O 2p electrons to form strong covalent bonding which results in the relative displacement of Pb cage with respect to the O-octahedron. This results in increase ferroelectric properties of PbTiO3.
    However the question is that in the covalent state of the Pb2+ will it appear as Pb4+ state in the Pb K-edge? The reason argued here is that the Pb will lose the 6s2 electrons to form the bond and hence appear to be Pb4+. Hence the argument placed by this pool of thought is from the EXAFS data what appears to be Pb4+ is actually the covalently bonded Pb2+ while what appears to be Pb2+ is actually the ionic type Pb2+.
    What is the oxidation state of Pb and Ti in PbTiO3 ?

    Comments on this issue will be appreciated.
    Last edited: Oct 28, 2009
  2. jcsd
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