Tl+ Ion Conductivity in RbxTl(1-x)I for 0 ≤ x ≤ 0.10, Coexistence of Mixed Phases, and Phase Stabilization
✍ Scribed by Peng-Nian Huang; E.A. Secco
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 280 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0022-4596
No coin nor oath required. For personal study only.
✦ Synopsis
The ac electrical conductivity versus temperature dependence of (\mathrm{Rb}{x} \mathrm{Tl}{(1-x)} \mathrm{I}) for (0 \leq x \leq 0.10) is reported. The solid-solid phase transition (yellow) (\beta)-TII (\rightleftarrows) (red) (\alpha)-TII occurs at (172^{\circ} \mathrm{C}) with transition enthalpy (\Delta H_{1}=865 \mathrm{~J} / \mathrm{mole}) and is accompanied by a sharp jump in conductivity, ca. two orders of magnitude. The reverse (\alpha \rightarrow \beta) transition exhibits a distinct hysteresis dependent on pressure and rate of cooling. The high conductivity (\alpha)-phase can be obtained at room temperature (i) by application of pressure to the (\beta)-solid, (ii) by rapid quenching of the melt, and (iii) by incorporating (5-9 \mathrm{~mole} % \mathrm{RbI}) in TII lattice. The conductivity data and (Q_{\mathrm{c}}) values, while sensitive to sample history and pretreatment, show reproducible behavior. The observed (Q_{\mathrm{c}}(\mathrm{eV})) values are (0.39 \pm 0.04) for the cool mode of compressed (\alpha) - and (\beta)-'TII and the heat mode of (\mathrm{Rb}{0.05} \mathrm{Tl}{1,951} 1,0.50-0.62) for all (\alpha)-TII samples and (\mathrm{Rb}{0,60} \mathrm{Tl}{0,901} \mathrm{I}), and 0.64-0.97 for all (\beta)-TII samples prior to the (\beta-\alpha) transition. No solid-solid phase transition is observed for (\mathrm{Rbl}) and its conductivity is lower than that of (\mathrm{Tll}) by a factor of (10^{5} \mathrm{at} \sim 175^{\circ} \mathrm{C}). The mechanism and structure interpretalions of these results are presented. of 1993 Ac:utemic press, Inc.