Silicon isotope enrichment for low activation

Abstract

Silicon isotope separation from hexafluorodisilane (Si 2F 6) has been examined using a CO 2 pulsed laser. Si 2F 6 containing certain isotopes was preferentially decomposed to SiF 4 depending on the wavenumber ( k) of the laser. 29Si and 30Si were concentrated in the SiF 4 produced at k=945–955 cm −1, and in the residual Si 2F 6 at k=970–980 cm −1. The SiF 4 containing 30Si of about 43.3% and 29Si at a maximum of 12.3% was continuously produced with a yield of 4.4% at k=951.203 cm −1 and 9.6% at 956.205 cm −1, respectively. The decomposition reaction of Si 2F 6 by the infrared laser irradiation could be explained as Si 2F 6(gas)+ n h ν→SiF 4(gas)+SiF 2(solid), calculated from a mass balance analysis of the experimental results. A 30Si concentration higher than 90% was estimated to be achievable by repeating the irradiation of the residual Si 2F 6 at around k=975 cm −1 and finally decomposing the Si 2F 6 to SiF 4 at k=951.203 cm −1. SiC enriched with 29Si and 30Si was predicted to show an excellent low activation behavior in fusion neutron environments.