Sn-119 M{umlt o}ssbauer study of dilute tin-lead alloys
- Physics Department, Purdue University, West Lafayette, Indiana 47907-1396 (United States)
M{umlt o}ssbauer spectroscopy has been performed using the {sup 119}Sn resonance on a variety of low-concentration tin in lead samples, ranging from 1.3 at.thinsp{percent} to 18.5 at.thinsp{percent} tin in lead. We observe three basic resonances, which we identify as dispersed tin in lead (I), precipitated {beta} (white) tin in lead (II), and precipitated {alpha} (gray) tin in lead (III), where the latter is only observed below 286 K. Contrary to earlier published results that reported an anomalous falloff in the elastic fraction for dispersed tin in lead, we find only the typical temperature dependence. The M{umlt o}ssbauer temperature is found to be 104 K for the dispersed state, as found from a Debye model analysis based on the transmission integral. Both this M{umlt o}ssbauer temperature and the isomer shift relative to a CaSnO{sub 3} source agree with earlier published values within experimental error. For the precipitated state (II), it is found in the initial stages of precipitation both the isomer shift and the measured M{umlt o}ssbauer temperature are close to that of the dispersed state (I). As the sample is annealed or cold worked, the precipitates grow and both the isomer shift and the characteristic M{umlt o}ssbauer temperature approach that of {beta}-Sn, 140 K. The precipitation-dissolution reaction is traced using a sample containing 18.5 at.thinsp{percent} tin in lead by annealing at progressively higher temperatures and following changes in the isomer shift. Dissolution is found to begin as low as 360(+15/{minus}5)thinspK. A significant result that has not been reported by earlier investigators of this system is the observation using M{umlt o}ssbauer spectroscopy of the {alpha} phase of tin (III). Furthermore, the formation of this phase takes place without the usual long incubation period required when a lead host matrix is not used. Moreover, a technique for curve fitting such M{umlt o}ssbauer spectra based on an analytic expansion of the transmission integral is demonstrated that isolates each component in the unresolved resonance. We find that the M{umlt o}ssbauer effect technique can be used for assessing the phase diagram in systems such as the Sn-Pb alloy, and our results indicate that the accepted phase diagram may need refinement. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 641643
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 58, Issue 10; Other Information: PBD: Sep 1998
- Country of Publication:
- United States
- Language:
- English
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