تقرير
Pressure tuning the Jahn-Teller transition temperature in NaNiO$_2$
| العنوان: | Pressure tuning the Jahn-Teller transition temperature in NaNiO$_2$ |
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| المؤلفون: | Nagle-Cocco, Liam A V, Bull, Craig L, Dutton, Sian E, Ridley, Christopher J |
| سنة النشر: | 2022 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Materials Science |
| الوصف: | NaNiO$_2$ is a layered material consisting of alternating layers of NaO$_6$ and Jahn-Teller-active NiO$_6$ edge-sharing octahedra. At ambient pressure it undergoes a broad phase transition from a monoclinic to rhombohedral structure between $\sim$465 K and $\sim$495 K, associated with the loss of long-range orbital ordering. In this work, we present the results of a neutron powder diffraction study on powdered NaNiO$_2$ as a function of pressure and temperature from ambient pressure to $\sim$5 GPa between 290 K and 490 K. The 290 K and 460 K isothermal compressions remained in the monoclinic phase up to the maximum pressures studied, whereas the 490 K isotherm was mixed-phase throughout. The unit-cell volume was fitted to a 2nd-order Birch-Murnaghan equation of state, with $B=113(1)$ GPa. We observe at 490 K that the fraction of Jahn-Teller-distorted phase increases with increasing pressure, from 67.8(6)% at 0.71(2) GPa to 80.2(9)% at 4.20(6) GPa. Using this observation, in conjunction with neutron diffraction measurements at 490 K from 5.46(9) GPa to 0.342(13) GPa, we show that the Jahn-Teller transition temperature increases with pressure. Our results are used to present a structural pressure-temperature phase diagram for NaNiO$_2$. To our knowledge, this is the first diffraction study of the effect of pressure on the Jahn-Teller transition temperature in materials with edge-sharing Jahn-Teller-distorted octahedra, and the first variable-pressure study on a JT-active edge-sharing nickelate. Comment: Accepted in ACS Inorganic Chemistry |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2202.09127 |
| رقم الأكسشن: | edsarx.2202.09127 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |