In¯uence of post-implantation thermal and laser annealing on the stability of metal±alloy nanoclusters in silica G. Battaglin a , E. Cattaruzza a , C. de Julian Fernandez b , G. De Marchi b , F. Gonella a , G. Mattei b , C. Maurizio b , P. Mazzoldi b, * , A. Miotello c , C. Sada b , F. D'Acapito d a INFM, Dip. di Chimica Fisica, Universit a di Venezia, Dorsoduro 2137, I-30123 Venice, Italy b INFM, Dip. di Fisica `Galileo Galilei', Universit a di Padova, via Marzolo 8, I-35131 Padua, Italy c INFM, Dip. di Fisica, Universit a di Trento, via Sommarive 14, I-38050 Povo Trento), Italy d INFM, ESRF, GILDA-CRG, B.P. 220, F-38043 Grenoble, France Abstract The eect of thermal or laser annealing on the evolution of binary alloy clusters in sequentially ion-implanted Au/Cu or Ag/Au silica glasses has been studied. In the case of Au/Cu system the selective eect of oxidizing atmosphere on alloy decomposition has been investigated as a function of the temperature and time, evidencing that alloy decom- positiontakesplacewithCuoxidation.IntheAuAgsystemthedecompositionprocessisslowerthanintheAuCucase, due to lower silver±oxygen reactivity. On the contrary, laser annealing is able to promote alloy formation and/or composition modi®cation even in systems with partially or completely separated components. Ó 2001 Elsevier Science B.V. All rights reserved. PACS: 61.73.Ww; 81.05.Pj; 81.05.Bx; 61.64.+w; 81.40.)z Keywords: Ion implantation; Glass composites; Alloys; Nanoclusters; Annealing 1. Introduction Composite materials formed by metal or semi- conductor nanoclusters embedded in an insulating host are peculiarly interesting for the enhancement of the nonlinear optical properties of the matrix and for their magnetic applications [1±5]. Alloy- based metal nanoclusters in insulating matrices have recently attracted a great interest in the ®eld of nanostructured materials science due to the possibility of synthesizing composite materials which, besides the well-known size-dependence of their electronic and magnetic properties, exhibit peculiar composition-dependent properties [5,7]. In this paper, we present a study of the structural andopticalpropertiesofnanocompositesprepared by sequential ion implantation of Au and Cu ions or Au and Ag ions in a fused silica matrix. Par- ticular emphasis will be put on investigating the eect on alloy stability of two kinds of annealing procedures: i) thermal annealing in oxidizing Nuclear Instruments and Methods in Physics Research B 175±177 2001) 410±416 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +39-49-8277002; fax: +39-49- 8277003. E-mail address: mazzoldi@padova.infm.it P. Mazzoldi). 0168-583X/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved. PII:S0168-583X00)00558-9