Metal/Oxide Interfaces

Title: Metal-oxide interfaces (Marshall Stoneham, John Harding)

Context: The metal-oxide interface is one of the commonest in technology: the protective oxide on beverage cans, the non-protective rust, electrodes on dielectrics, catalysts and sensor materials on oxide substrates. Some of these systems are very complicated: spent fuel-zircalloy clad interfaces for nuclear reactor fuels involve systems with nearly 100 elements. We have been developing both simple and state-of-the-art methods to understand and predict the properties of such interfaces. We were the first to recognise the importance of the image interaction (the fact that the charged ions in the oxide polarise the metal), partly through our analysis of the systematices of wetting of oxides by metals. We were also the first to realise that this allowed one to explain other phenomena, like anodic bonding and radiation-enhanced adhesion.

Current activities: Our current emphasis includes:

(a) State-of-the-art electronic structure calculations to test ideas and to address cases which simpler methods cannot handle easily (certain tricky interfaces, like MgO 110; cases where there are surface defects which can trap charge)

(b) Studies of the nucleation and growth of metal particles on ionic substrates

(c) Approaches which validate simple methods for the most complex systems.

People involved (including external collaborators)

Yuri Zhukovski and Eugene Kotomin (Riga); Patrick Jacobs (Western Ontario), John Venables (Arizona/Sussex); Sasha Shluger (UCL)

Relevant papers (incomplete list)

198. Metal/Non-Metal and other Interfaces: The Role of Image Interactions
A M Stoneham and P.W.Tasker 1985 J Phys C.18 L543 (also TP1122).

123. Ceramic Surfaces: Theoretical Studies. (Invited paper, American Ceramic Society)
A M Stoneham 1981 J. Am. Ceram. Soc. 64, 54-60.

172. Systematics of Metal-Insulator Interfacial Energies: A New Rule for Wetting and Strong Catalyst Support Interactions.
A M Stoneham 1983 Appl. Surf. Sci. 14, 249-259.

190. Electronic Structure and Properties of Oxide Surfaces and Interfaces. (Invited talk 1984, Material Research Society, Boston)
A.M.Stoneham and P.W.Tasker 1985, Mat. Res. Soc. Symp. 40 291-301.

215. Oxide Surfaces : The Basic Processes of Sensor Behaviour
A M Stoneham 1987 pps. 151-168 of "Solid State Gas Sensors" (edited P.T. Moseley, B.C.Tofield; Adam Hilger).

219. Oxide Interfaces: Theory of Oxide-Oxide and Oxide-Metal Interfaces (invited talk, 1986 Berkeley Conference).
A M Stoneham and P.W. Tasker 1986, pps. 155-165 of "Ceramic Microstructures 186: Role of Interfaces" (Plenum Press; edited J.A. Pask)

232. Theory of Ceramic Surfaces
A.M. Stoneham and P.W. Tasker 1988, pps 1-22 of "Surface and Near Surface Chemistry of Oxide Materials", (edited L-C Dufour, J. Nowotny), Elsevier.

255. Approaches to Modelling Metal/Ceramic Interfaces,
M.W. Finnis, A.M. Stoneham' and P.W. Tasker, 1990, p 35 of "Metal-Ceramic Interfaces" (edited M Rühle and et al), Oxford: Pergamon Press

310. Atomistic Modelling of the Metal/Oxide Interface with Image Interactions.
D M Duffy, J H Harding and A M Stoneham. 1992 Acta Met Mater 40, Suppl pps S 11-16.

317. Atomistic modelling of metal/oxide interfaces with image interactions.
D M Duffy, J H Harding, A M Stoneham (appendix by J R Willis) 1993 Phil Mag A67 865-882.

332. Energies of Point Defects Near Metal-Oxide Interfaces.
D M Duffy J H Harding, A M Stoneham. 1995 J Appl Phys 76 2791-2798.

333. Understanding Wetting & Spreading: Non-reactive Metals on Oxides and Similar Systems
A M Stoneham D M Duffy, J H Harding 1994, in High Temperature Capillarity, edited N Eustathopoulos; Slovak Academy of Sciences) pps l-10

339. A simulation of the NiO/Ag interface with point defects,
D M Duffy, J H Harding, A M Stoneham 1995, Acta Metall Mater 43 (4) 1559-1568.

354. A calculation of the structure and energy of the Nb/Al203 interface.
D M Duffy, J H Harding and A M Stoneham 1996 Acta Met Mater 44 8 pp 3293-3298

373 Predicting growth processes: atomistic modelling of metal atoms on ionic substrates
J H Harding, A M Stoneham and J A Venables 1998 Phys Rev B51 6715-6719

390 A comparative theoretical study of teh Ag/MgO (100) and (110) interfaces
Y Zhukovskii, E A Kotomin, P W M Jacobs, A M Stoneham & J H Harding 1999  Surface Science ###

397 Modelling of Silver Adhesion on MgO(100) with defects
Y Zhukovskii, E A Kotomin, P W M Jacobs, A M Stoneham & J H Harding 1999  J Phys Cond Mat ###

398 Modelling of Metal Adhesion on Oxide surfaces with defects
Y Zhukovskii, E A Kotomin, P W M Jacobs & A M Stoneham 1999  Phys Rev Letters ###

Cross-links Some of the ideas connect with the silicon oxidation science; others connect with studies of sensors, of oxide surfaces and with defect processes generally. There is a specific problem of the stability of defect charge states which is often misuderstood, and which emerges here and elsewehere.