Journal of Solid State Chemistry 177 (2004) 3014–3020 Microwave-assisted selective preparation and characterization of Li 21 Si 5 and Li 17 Sn 4 Gen-Tao Zhou, a,b Oleg Palchik, a Israel Nowik, c R. Herber, c Yuri Koltypin, a and Aharon Gedanken a, * a Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel b School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, People’s Republic of China c Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel Received 25 December 2003; received in revised form 22 April 2004; accepted 24 April 2004 Available online 24 June 2004 Abstract Two types of intermetallic lithium alloys, Li 21 Si 5 and Li 17 Sn 4 (previously Li 22 Si 5 and Li 22 Sn 5 ), were prepared for the first time using microwave-assisted solid-state reaction. The optimum oven power for their preparation is 80–60%, and the irradiation times are 5 min for Li 21 Si 5 or 10 min for Li 17 Sn 4 . A cheap alumina crucible was found to be the most suitable container in quick (less than 10min) microwave reactions for Li-containing alloys. The synthesized compounds were characterized by PXRD. Mo¨ ssbauer spectroscopy was used to characterize Li 17 Sn 4 under different conditions. The hyperfine interaction parameters of 119 Sn in Li 17 Sn 4 show a typical Li–Sn alloy Sn isomer shift (1.88 mm/s). The oxidization processes of the two intermetallic lithium alloys in air were investigated. The microwave method was found to be simple, fast and efficient, with high selectivity for the preparation of these compounds. r 2004 Elsevier Inc. All rights reserved. Keywords: Intermetallic alloy; Microwave radiation; Solid-state reaction 1. Introduction There is a great deal of interest in the development of new anode and cathode materials for Li batteries. The search for the new Li-containing anode has continued for more than a few decades. The use of Li-alloys as an anode material was found to be very advantageous due to its higher gravimetric and volumetric theoretical capacity and extra safety relative to the carbonaceous anodes [1–4]. Unfortunately, poor cycling performance was associated with the use of these anodes, due to the mechanical defects that develop during volume expan- sion (up to 200%) of the alloys through lithium insertion [5,6]. Recently, it was found that using nanoparticles of these alloys could prevent the mechanical failure of the anode [7–9]. The nanoparticles were easily prepared by ball-milling techniques. However, the preparation of the bulk alloys is not an easy process and that could prevent the commercialization of these materials. There are a few reasons for the difficulty in the fabrication of the Li- alloys: (1) Li-alloys are currently prepared by a classical high temperature method, which demands a very high reaction temperature (p1000  C) and prolonged heating (days); (2) due to the highly corrosive nature of the molten Li, special reaction containers like expensive tantalum are needed. These drawbacks motivated the development of a new synthetic method that overcomes these problems and facilitates product formation. The microwave-assisted reaction method is presented. This method does not suffer from the disadvantages of the classical preparation technique. Microwave-assisted chemical reactions have only recently been developed, but they have already been shown to be superior to other synthetic techniques in the fields of organic and analytical chemistry [10–18]. Its extension to inorganic chemistry was much slower, but there are already a few examples of the application of microwave heating to inorganic synthesis [19–34]. We ARTICLE IN PRESS *Corresponding author. Fax: 972-3-535-1250. E-mail address: gedanken@mail.biu.ac.il (A. Gedanken). URL: http://www.biu.ac.il/ESC/ch/faculty/gedanken/gedint.html. 0022-4596/$ - see front matter r 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.jssc.2004.04.045