Negative linear compressibility and complex phase behaviour in 7Li2CO3

Abstract

We present a combination of neutron powder-diffraction measurements demonstrating negative linear compressibility and irregular thermal expansion in 7Li2CO3. This is shown to be due to an interplay between the tilting of the rigid carbonate group and the shear strain in the unit cell, which leads to a first-order transition from monoclinic to hexagonal symmetry. The phase evolution is shown to be highly sensitive to the level of hydrostaticity in the sample. Under hydrostatic conditions, the sample begins transformation at 8.5 GPa leading to a change from tetrahedral to octahedral Li coordination. Symmetry adapted basis mode analysis, combined with density functional theoretical (DFT) calculations and Raman spectroscopy, is used to show that this transition is reverse proper ferroelastic in nature.

Graphical abstract: Negative linear compressibility and complex phase behaviour in 7Li2CO3

Supplementary files

Article information

Article type
Paper
Submitted
21 Mar 2025
Accepted
12 May 2025
First published
14 May 2025
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2025, Advance Article

Negative linear compressibility and complex phase behaviour in 7Li2CO3

C. J. Ridley, F. Orlandi, C. L. Bull, N. P. Funnell, J. K. Hinton, R. S. Perry, S. Hull and R. Wurr, J. Mater. Chem. A, 2025, Advance Article , DOI: 10.1039/D5TA02325D

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