Technetium Chemistry in the Solar Nebula

Details Technetium Chemistry in the Solar Nebula Technetium Chemistry in the Solar Nebula

Jul 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993metic..28..346f&link_type=abstract

Meteoritics, vol. 28, no. 3, volume 28, page 346

Computer Science

1

Condensation, Cosmochemistry, Noble Metals, Refractory Inclusions, Refractory Siderophile Elements, Technetium

Scientific paper

Introduction. Yin et al [1] recently presented evidence for live ^99Tc in the solar nebula. Technetium is siderophile and is chemically similar to Re. However, its cosmochemistry has not been examined. Here we present the first study of Tc chemistry in the solar nebula. Methods and Results. Condensation calculations for a multicomponent metal alloy containing W, Re, Os, Ir, Mo, Ru, Pt, Rh, Co, Ni, Fe, Pd, Cr, and Tc were done using the METKON code [2]. The metal and oxide gases included in the calculations are listed by [2] and the Tc compounds considered are Tc(s,l,g), Tc(sub)2(g), Tc(sub)2O(sub)7(s,g), TcO(sub)2(s), and TcO(sub)3(s). The 50% condensation temperatures for Tc, along with those for Ir, Ru, and Mo are listed in Table 1, which illustrates the similar volatilities of these elements. However, Table 2 shows that larger Tc/Mo fractionations are produced under oxidizing conditions. The effects of sulfurization on Tc, Ru, and Mo chemistry were calculated by considering the reaction TcS(sub)2(s) + M = MS(sub)2(s) + Tc where M = Ru or Mo. The calculated Gibbs free energies for the reactions suggest that MoS(sub)2 is more stable than TcS2 but that TcS(sub)2 and RuS(sub)2 have similar stabilities. Conclusions. Technetium behaves as a refractory siderophile in the solar nebula. Only small Tc/Ru fractionations are produced by volatility effects. Much larger Tc/Mo fractionations can be produced by condensation under oxidizing conditions or by sulfurization of metal alloys. Acknowledgments. Work at Washington University was supported by grants from the NASA Planetary Atmospheres and Origins of Solar Systems Programs. References. [1] Yin Q. et al. (1992) Meteoritics, 27, 310. [2] Fegley B. Jr. and Palme H. (1985) Earth Planet. Sci. Lett., 72, 311-326. Table 1, which appears here in the hard copy, shows 50% condensation temperatures (K) for ideal solid solution in refractory metal nuggets. The uncertainties in the Tc(s,g) thermodynamic data give an uncertainty of +-10 K in the condensation temperatures. Table 2, which appears here in the hard copy, shows Tc/Mo fractionations under oxidizing conditions (1650 K, 10^-3 bars).

Affiliated with

Also associated with

No associations

Rating

Technetium Chemistry in the Solar Nebula does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Technetium Chemistry in the Solar Nebula, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Technetium Chemistry in the Solar Nebula will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1072335