Proceedings of the 43rd International Field Emission Symposium
J. Phys. IV France 06 (1996) C5-205-C5-210
Materials Applications of an Advanced 3-Dimensional Atom ProbeA. Cerezo1, D. Gibuoin1, S. Kim1, S.J. Sijbrandij1, F.M. Venker2, P.J. Warren1, J. Wilde1 and G.D.W. Smith1
1 Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
2 Department of Applied Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
An advanced 3-dimensional atom probe system has been constructed, based on an optical position-sensitive atom probe (OPoSAP) detector with energy compensation using a reflectron lens. The multi-hit detection capability of the OPoSAP leads to significant improvements in the efficiency of the instrument over the earlier serial position-sensing system. Further gains in efficiency are obtained by using a biassed grid in front of the detector to collect secondary electrons generated when ions strike the interchannel area. The improvement in detection efficiency gives enhanced performance in the studies of ordered materials and the determination of site occupation. Energy compensation leads to a much improved mass resolution (m/Δm full width at half maximum) making it possible to map out the 3-dimensional spatial distributions of all the elements in complex engineering alloys, even when elements lie close together in the mass spectrum. For example, in the analysis of a maraging steel, this allows separation between the 61Ni2+ and 92Mo3+ peaks, which are only 1/6 of a mass unit apart.
© EDP Sciences 1996