Evidence for double valence fluctuation in metallic oxides of lead

Ganguly, P and Hegde, MS (1988) Evidence for double valence fluctuation in metallic oxides of lead. In: Physical Review B: Condensed Matter, 37 (10). 5107 -5112.

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Abstract

The possible role of double valence fluctuation in both lead and oxide ions with reference to metallization in oxides of lead is examined by x-ray-photoemission spectroscopy, ultraviolet-photoemission spectroscopy (UPS), and 207Pb NMR studies. The double valence fluctuations may be viewed as Pb4++2O2-⇄Pb2+O22-. While the insulating oxides PbO, Pb3O4, and Sr2PbO4 show a single oxide ion, O2- characterized by O(1s) at 529.7 eV, the insulating peroxide BaO2 is characterized by the ion O22- with a single O(1s) at 533 eV. The metallic PbO2, BaPbO3, BaBiPbO3, and SrPbO3 showed the occurrence of both O2- and O22- ions. The valence band in these compounds has also been studied by UPS, and clear evidence for the coexistence of O2- and O22- is seen in PbO2. A simultaneous study of 207Pb NMR suggests that the Pb ion could also exist in mixed-valence states. Qualitative arguments are presented to rationalize the existence of such mixed valences of the anion in metal oxides in general and their role in superconductivity.

Item Type:	Journal Article
Publication:	Physical Review B: Condensed Matter
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	16 Sep 2010 06:20
Last Modified:	19 Sep 2010 06:16
URI:	http://eprints.iisc.ac.in/id/eprint/32180

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