Context: The needs for gas sensors include those for CO (fire), ozone, NOX (pollution) and many others. The key issues are (a) sensitivity, (b) selectivity to the chosen gas, (c) insensitivity to moisture, (d) low power operation. Past activities have included the analysis of systematic data on many gases and oxides; these showed a number of important rules describing sensor operation.

Current activities: The science of sensors involves the states of adsorbed species on oxide surfaces, oxide surface defects, oxide microstructure, electron transfer processes, and issues of charge state stability. We have been looking both at specific surface defect issues (by state-of-the-art methods, by simpler methods based on interatomic potentials, and by even simpler methods) to try to build a coherent and systematic understanding.
 
 

People involved (including external collaborators)

David E Williams founded Capteur, a small but growing firm making gas sensors.

EPSRC funded. Others at UCL with interests in the theory of oxide surfaces include Sasha Shluger, Lev Kantorovich, Jacob Gavartin, Mike Gillan, and Frances Jones (Eastman Dental Institute). Others outside UCL with interests in oxide surfaces include Andrew Briggs and Adrian Sutton (Oxford, Materials Dept), and Bill Mackrodt (St Andrew's)

Recent (or simply relevant) papers

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).

297. Oxide semiconductors: Patterns of Gas Response Behaviour according to Material Type
P T Moseley, A M Stoneham and D E Williams 1991, pps 108-138 of "Techniques and Mechanisms in Gas Sensing" (edited P T Moseley, J O W Norris, D E Williams, Bristol: Adam Hilger).

71. Theory of the Fs+ Surface Centre in MgO
R.R. Sharma and A M Stoneham 1976 J.Chem. Soc (Faraday II) 72, 913-9.

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

167. Conductivity and "Negative U" for Ionic Grain Boundaries
D.M. Duffy and A M Stoneham 1983 J. Phys. C16, 4087-4092 (also TP 975).

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.

223. Surfaces and Interfaces of Ionic Solids
A M Stoneham 1987 Crystal Lattice Defects and Amorphous Materials 14 173-182 (Invited Talk, International Conference in Defects in Ionic Crystals, El Escorial, Spain 1986).

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.

254. A Theoretical Study of Desorption Induced by Electronic Structure Transitions in Alkali Halides
N. Itoh, A.M. Stoneham and A.H. Harker, 1989, Surf. Sci. 217 (1989) 573-589.

316. How do they stick together? The statics and dynamics of interfaces.
A M Stoneham, M M D Ramos and A P Sutton 1993 Phil Mag A67 797-811.

319. Equilibria and Electronic Processes. (Festschrift for J M Thomas)
A M Stoneham and M M D Ramos 1993 J Sol St Chem 106 2-12.

320. Dynamics of Liquid Drop Spreading in Metal-Metal Systems.
J C Ambrose, M G Nicholas and A M Stoneham 1993 Acta Metallurgica et Materialia, 41 2395-2401.