ISIS Neutron and Muon Source Data Journal

Variable pressure and temperature Neutron Diffraction study of ?defect free? LiNiO2 : a NaNiO2 analogue

Abstract: The Li analogue of NNO, LiNiO2 (LNO), stabilises in R3 m phase at room temperature and is known to have local JT distortions but no cooperative JT ordering. Unlike NNO, LNO is prone to significant anti-site disorder and subtle changes in stoichiometry which are known to have a dramatic effect on the magnetic properties of the system. It is proposed this disorder supresses the cooperative JT ordering even at low temperatures. Recently defect free samples of LNO have been prepared via ion-exchange (IE-LNO) which has different electrochemical properties. In our published work (J. Am. Chem. Soc. 2025, 147 (32), 29042 29051) using combined SXRD and NPD we find IE-LNO to be isostructural with NNO at RT and on heating a second order phase transition at T ~ 350 K to a rhombohedral structure is observed. Notably the magnitude of the JT distortion in LNO is much smaller than that observed in NNO. The similarity of the structure of IE-LNO to NNO makes it an ideal candidate for an in-depth NPD study as a function of temperature and pressure. The reduced magnitude of the JT distortion and the lower T for the structural phase transition mean that it should be possible to observe both monoclinic and rhombohedral structures as the temperature/pressure is varied using the PEARL Paris-Edinburgh pressure cell.

Principal Investigator: Dr Farheen Sayed
Experimenter: Mr Surat Prempluem
Experimenter: Mr James Steele
Experimenter: Ms Celia Chen
Experimenter: Professor Clare Grey
Experimenter: Professor Sian Dutton
Local Contact: Dr Craig Bull
Experimenter: Mr George Phillips

DOI: 10.5286/ISIS.E.RB2610488

ISIS Experiment Number: RB2610488

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
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Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Dr Farheen Sayed et al; (2026): Variable pressure and temperature Neutron Diffraction study of ?defect free? LiNiO2 : a NaNiO2 analogue, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2610488

Data is released under the CC-BY-4.0 license.