تقرير
A Low Temperature Structural Transition in Canfieldite, Ag$_8$SnS$_6$, Single Crystals
| العنوان: | A Low Temperature Structural Transition in Canfieldite, Ag$_8$SnS$_6$, Single Crystals |
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| المؤلفون: | Slade, Tyler J., Gvozdetskyi, Volodymyr, Wilde, John M., Kreyssig, Andreas, Gati, Elena, Wang, Lin-Lin, Mudryk, Yaroslav, Ribeiro, Raquel A., Pecharsky, Vitalij K., Zaikina, Julia V., Budko, Sergey L., Canfield, Paul C. |
| سنة النشر: | 2021 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Materials Science |
| الوصف: | Canfieldite, Ag$_8$SnS$_6$, is a semiconducting mineral notable for its high ionic conductivity, photosensitivity, and low thermal conductivity. We report the solution growth of large single crystals of Ag$_8$SnS$_6$ of mass up to 1 g from a ternary Ag-Sn-S melt. On cooling from high temperature, Ag$_8$SnS$_6$ undergoes a known cubic (F-43m) to orthorhombic (Pna2$_1$) phase transition at $\approx$ 460 K. By studying the magnetization and thermal expansion between 5-300 K, we discover a second structural transition at $\approx$ 120 K. Single crystal X-ray diffraction reveals the low temperature phase adopts a different orthorhombic structure with space group Pmn2$_1$ (a = 7.6629(5) \AA, b = 7.5396(5) \AA, c = 10.6300(5) \AA, Z = 2 at 90 K) that is isostructural to the room temperature forms of the related Se-based compounds Ag$_8$SnSe$_6$ and Ag$_8$GeSe$_6$. The 120 K transition is first-order and has a large thermal hysteresis. Based on magnetization and thermal expansion data, the room temperature polymorph can be kinetically arrested into a metastable state by rapidly cooling to temperatures below 40 K. We lastly compare the room and low temperature forms of Ag$_8$SnS$_6$ with its argyrodite analogues, Ag$_8$TQ$_6$ (T = Si, Ge, Sn; Q = S, Se), and identify a trend relating the preferred structures to the unit cell volume, suggesting smaller phase volume favors the Pna2$_1$ arrangement. We support this picture by showing that the transition to the Pmn2$_1$ phase is avoided in Ge alloyed Ag$_8$Sn$_{1-x}$Ge$_x$S$_6$ samples as well as pure Ag$_8$GeS$_6$. Comment: 45 pages, 13 figures |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2110.07508 |
| رقم الأكسشن: | edsarx.2110.07508 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |