Nature of the Band Gap and Origin of the Conductivity of PbO2 Revealed by Theory and Experiment
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2011Citation:
David O. Scanlon, Aoife B. Kehoe, Graeme W. Watson, Martin O. Jones, William I. F. David, David J. Payne, Russell G. Egdell, Peter P. Edwards, Aron Walsh , Nature of the Band Gap and Origin of the Conductivity of PbO2 Revealed by Theory and Experiment, Physical Review Letters, 107, 246402, 2011, 5Download Item:
Abstract:
Lead dioxide has been used for over a century in the lead-acid battery. Many fundamental questions concerning PbO2 remain unanswered, principally: (i) is the bulk material a metal or a semiconductor, and (ii) what is the source of the high levels of conductivity? We calculate the electronic structure and defect physics of PbO2, using a hybrid density functional, and show that it is an n-type semiconductor with a small indirect band gap of ~0.2??eV. The origin of electron carriers in the undoped material is found to be oxygen vacancies, which forms a donor state resonant in the conduction band. A dipole-forbidden band gap combined with a large carrier induced Moss-Burstein shift results in a large effective optical band gap. The model is supported by neutron diffraction, which reveals that the oxygen sublattice is only 98.4% occupied, thus confirming oxygen substoichiometry as the electron source.
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Grant Number
Science Foundation Ireland (SFI)
06/IN.1/I92/EC07
Science Foundation Ireland (SFI)
06/IN.1/I92
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http://people.tcd.ie/watsongDescription:
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Science Foundation Ireland (SFI)Science Foundation Ireland (SFI)
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Physical Review Letters107
246402
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Chemistry, Lead dioxideSubject (TCD):
Nanoscience & MaterialsDOI:
http://dx.doi.org/10.1103/PhysRevLett.107.246402Metadata
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