Binghamton University
Department of Physics, Applied Physics and Astronomy
PHYSICS COLLOQUIUM
“Understanding the Electronic Structure of Metal Oxides”
Dr. David Payne
University of Oxford
Abstract:
The electronic and optical properties of metal oxides are more diverse than for any other class of
material. Oxides range from wide gap insulators (Al2O3), through semiconductors (TiO2),
metallic conductors (ReO3), to superconductors (HgBa2Ca2Cu3O8+x). This behavior cannot
simply be understood in simple structural terms. Thus oxides displaying the rock salt structure
include the insulator MgO, the n-type semiconductor CdO, and metallic conductors such as TiO.
Similarly oxides with the rutile structure include insulators such as stoichiometric SnO2, as well
as metallic conductors such as PbO2. Techniques used to study the electronic structure have
traditionally been photoemission based. X-ray photoelectron spectroscopy (XPS) is a workhorse
technique for studying the filled states in solids. Recent developments have led to Hard X-ray
Photoelectron Spectroscopy (HAXPES) becoming an alternative to the typically more surface
sensitive measurements of XPS. This technique, in conjunction with X-ray emission/absorption
spectroscopy (XES/XAS), as well as state of the art density functional theory (DFT) calculations
has led to some important discoveries.
This talk will cover:
(1) Understanding why lead dioxide is metallic.
(2) A revision of the lone-pair model.
(3) A re-evaluation of the band-gap of indium oxide.
As well as discussing these results, the development of new techniques (Atom Probe
Tomography (APT)), as a tool to understand the location of dopant atoms in host oxide
materials, will be discussed, in particular with respect to the dilute magnetic oxide system
(DMO) Cr-doped In2O3.
Thursday, November 11, 2010
S2 Bldg. Room 144
PRESENTATION 2:30 PM– 3:30PM
ALL WELCOME – COFFEE AND REFRESHMENTS AT 2:20PM