Kinetics of the cubic-to-hexagonal phase transformation in ice doped with Mössbauer ions
✍ Scribed by A.J. Nozik; M. Kaplan
- Publisher
- Elsevier Science
- Year
- 1967
- Tongue
- English
- Weight
- 412 KB
- Volume
- 1
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The transformation of cubic to hexagonal ice has been studied by measuring the time dependence of the dependence of the disappearance and reappearance of the MSssbauer effect in frozen aqueous solutions containing ferrous, ferric and europic ions. The rate of transformation is significantly decreased, compared to pure ice, and depends strongly on the identity and concentration of the trapped ions. Our observations indicate that the transformation occurs in at least two stages, with an intermediate state vchich can persist for extended time periods. and during which no Mijssbauer resonance could be detected. III a recent paper [l] we reported a detailed Mtissbauer resonance study of ferrous ions trapped in an ice lattice by the quenching of aqueous solutions. Additional investigations have been carried out on ferr c, europic, and europous ions in ice, and th .s work will be reported in the near future.
A general feat .re of our model for ions trapped in ice is that aquated ions in solution can induce the format'on of metastable cubic ice (Ic) rather than nr rmal hexagonal ice (I), when the solution is s ddenly frozen by quenching in liquid nitrcgen. Tt..e cubic ice transforms to hexagonal ice at highe,' temperatures (--8OOC) with associated pronoxmed changes in the Mossbauer spectrum, inc!uding the apparent disappearance of the Mossbau?r resonance during part of the transition period. Our previous paper [lj described the static properties of ferrous ion trapped in cubic and hexagonal ice. in the present letter, we report on the kinetics of the cubic-tohexagonal ice phase transformation, as reflected in the time dependence of the Mossbauer resonance absorption by the trapped ions during the ice transition.
The MUssbauer effects of the 14.4-keV trar~sition in 57Fe and the 21.6-keV transition in l5lEu were used as environmental probes in the present work. The experiments were performed by quenching an aqueous solution to -196OC, * Supported by the U. S.Atomic Energy Commissiqn.