Compositional evolution of Pd-based nanoclusters under thermal annealing in ion implanted SiO 2 G. Mattei a, * , G. Battaglin b , V. Bello a , E. Cattaruzza b , C. De Julian a , G. De Marchi a , C. Maurizio a , P. Mazzoldi a , M. Parolin a , C. Sada a a INFM, Department of Physics, University of Padova, via Marzolo 8, I-35131 Padova, Italy b INFM, Department of Physical Chemistry, University of Venezia, Dorsoduro 2137, I-30123 Venezia, Italy Abstract Sequential ion implantation has been used to synthesize Pd-based alloy nanoclusters in SiO 2 . Three systems have been investigated (PdCu, PdAg and PdFe) in terms of nanocluster formation and stability under thermal annealing. In particular, we focused on the role played by the annealing atmosphere. A comparison is made with similar alloy-based systems obtained by sequential ion implantation in silica of Au–Ag or Au–Cu followed by annealing under similar conditions. Strong similarities have been found in the compositional evolution of Pd-based and Au-based nanoclusters. Ó 2004 Elsevier B.V. All rights reserved. PACS: 61.72.Ww; 81.05.Pj; 81.05.Bx; 61.46.+w Keywords: Ion implantation; Glass composites; Alloys; Nanoclusters 1. Introduction Single or sequential ion implantation is cur- rently used as a suitable technique for synthesizing nanoclusters (NCs) embedded in glasses [1–9], in particular for controlling the composition and/or the local environment of bimetallic nanoclusters [9,10]. This is of paramount importance for in- stance to control the position of the surface plasma resonance (SPR) of the composite. To this aim, the stability of the clusters upon post-implantation thermal annealings or under subsequent ion irra- diation [10] has to be investigated. In this paper we present experimental results on the effect of thermal annealing on bimetallic PdCu, PdAg and PdFe nanoclusters embedded in silica. Pd-based alloy nanoclusters are interesting for their catalytic properties, which are better than those of pure Pd, in particular for the formation of hydride compounds important for hydrogen stor- age. The influence of the annealing atmosphere (either oxidizing or reducing) on the formation of alloy clusters will be investigated. A comparison is made with similar alloy-based systems obtained by sequential ion implantation of Au–Ag and Au–Cu in silica, then annealed under similar conditions, to evidence the peculiar role played by the different * Corresponding author. Tel.: +39-049-827-7045; fax: +39- 049-827-7003. E-mail address: mattei@padova.infm.it (G. Mattei). 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2003.12.088 Nuclear Instruments and Methods in Physics Research B 218 (2004) 433–437 www.elsevier.com/locate/nimb