Dome-like pressure-temperature phase diagram of the cooperative Jahn--Teller distortion in NaNiO$_2$

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Autori principali: Nagle-Cocco, Liam A. V., Steele, James M. A., Deng, Shiyu, Zhang, Xiaotian, Daisenberger, Dominik, Genreith-Schriever, Annalena R., Saxena, Siddharth S., Grey, Clare P., Dutton, Si^an E.
Natura: Preprint
Pubblicazione: 2025
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author Nagle-Cocco, Liam A. V.
Steele, James M. A.
Deng, Shiyu
Zhang, Xiaotian
Daisenberger, Dominik
Genreith-Schriever, Annalena R.
Saxena, Siddharth S.
Grey, Clare P.
Dutton, Si^an E.
author_facet Nagle-Cocco, Liam A. V.
Steele, James M. A.
Deng, Shiyu
Zhang, Xiaotian
Daisenberger, Dominik
Genreith-Schriever, Annalena R.
Saxena, Siddharth S.
Grey, Clare P.
Dutton, Si^an E.
contents NaNiO$_2$ is a Ni$^{3+}$-containing layered material consisting of alternating triangular networks of Ni and Na cations, separated by octahedrally-coordinated O anions. At ambient pressure, it features a collinear Jahn--Teller distortion below $T^\mathrm{JT}_\mathrm{onset}\approx480$ K, which disappears in a first-order transition on heating to $T^\mathrm{JT}_\mathrm{end}\approx500$ K, corresponding to the increase in symmetry from monoclinic to rhombohedral. It was previously studied by variable-pressure neutron diffraction [ACS Inorganic Chemistry 61.10 (2022): 4312-4321] and found to exhibit an increasing $T^\mathrm{JT}_\mathrm{onset}$ with pressure up to ~5 GPa. In this work, powdered NaNiO$_2$ was studied via variable-pressure synchrotron x-ray diffraction up to pressures of ~67 GPa at 294 K and 403 K. Suppression of the collinear Jahn--Teller ordering is observed via the emergence of a high-symmetry rhombohedral phase, with the onset pressure occurring at ~18 GPa at both studied temperatures. Further, a discontinuous decrease in unit cell volume is observed on transitioning from the monoclinic to the rhombohedral phase. These results taken together suggest that in the vicinity of the transition, application of pressure causes the Jahn--Teller transition temperature, $T^\mathrm{JT}_\mathrm{onset}$, to decrease rapidly. We conclude that the pressure-temperature phase diagram of the cooperative Jahn--Teller distortion in NaNiO$_2$ is dome-like.
format Preprint
id arxiv_https___arxiv_org_abs_2503_18833
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dome-like pressure-temperature phase diagram of the cooperative Jahn--Teller distortion in NaNiO$_2$
Nagle-Cocco, Liam A. V.
Steele, James M. A.
Deng, Shiyu
Zhang, Xiaotian
Daisenberger, Dominik
Genreith-Schriever, Annalena R.
Saxena, Siddharth S.
Grey, Clare P.
Dutton, Si^an E.
Materials Science
Strongly Correlated Electrons
NaNiO$_2$ is a Ni$^{3+}$-containing layered material consisting of alternating triangular networks of Ni and Na cations, separated by octahedrally-coordinated O anions. At ambient pressure, it features a collinear Jahn--Teller distortion below $T^\mathrm{JT}_\mathrm{onset}\approx480$ K, which disappears in a first-order transition on heating to $T^\mathrm{JT}_\mathrm{end}\approx500$ K, corresponding to the increase in symmetry from monoclinic to rhombohedral. It was previously studied by variable-pressure neutron diffraction [ACS Inorganic Chemistry 61.10 (2022): 4312-4321] and found to exhibit an increasing $T^\mathrm{JT}_\mathrm{onset}$ with pressure up to ~5 GPa. In this work, powdered NaNiO$_2$ was studied via variable-pressure synchrotron x-ray diffraction up to pressures of ~67 GPa at 294 K and 403 K. Suppression of the collinear Jahn--Teller ordering is observed via the emergence of a high-symmetry rhombohedral phase, with the onset pressure occurring at ~18 GPa at both studied temperatures. Further, a discontinuous decrease in unit cell volume is observed on transitioning from the monoclinic to the rhombohedral phase. These results taken together suggest that in the vicinity of the transition, application of pressure causes the Jahn--Teller transition temperature, $T^\mathrm{JT}_\mathrm{onset}$, to decrease rapidly. We conclude that the pressure-temperature phase diagram of the cooperative Jahn--Teller distortion in NaNiO$_2$ is dome-like.
title Dome-like pressure-temperature phase diagram of the cooperative Jahn--Teller distortion in NaNiO$_2$
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2503.18833