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Hyde PA, Cen J, Cassidy SJ, Rees NH, Holdship P, Smith RI, Zhu B, Scanlon DO, Clarke SJ. Lithium Intercalation into the Excitonic Insulator Candidate Ta 2NiSe 5. Inorg Chem 2023. [PMID: 37466301 PMCID: PMC10394660 DOI: 10.1021/acs.inorgchem.3c01510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
A new reduced phase derived from the excitonic insulator candidate Ta2NiSe5 has been synthesized via the intercalation of lithium. LiTa2NiSe5 crystallizes in the orthorhombic space group Pmnb (no. 62) with lattice parameters a = 3.50247(3) Å, b = 13.4053(4) Å, c = 15.7396(2) Å, and Z = 4, with an increase of the unit cell volume by 5.44(1)% compared with Ta2NiSe5. Significant rearrangement of the Ta-Ni-Se layers is observed, in particular a very significant relative displacement of the layers compared to the parent phase, similar to that which occurs under hydrostatic pressure. Neutron powder diffraction experiments and computational analysis confirm that Li occupies a distorted triangular prismatic site formed by Se atoms of adjacent Ta2NiSe5 layers with an average Li-Se bond length of 2.724(2) Å. Li-NMR experiments show a single Li environment at ambient temperature. Intercalation suppresses the distortion to monoclinic symmetry that occurs in Ta2NiSe5 at 328 K and that is believed to be driven by the formation of an excitonic insulating state. Magnetometry data show that the reduced phase has a smaller net diamagnetic susceptibility than Ta2NiSe5 due to the enhancement of the temperature-independent Pauli paramagnetism caused by the increased density of states at the Fermi level evident also from the calculations, consistent with the injection of electrons during intercalation and formation of a metallic phase.
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Affiliation(s)
- P A Hyde
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - J Cen
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
- Thomas Young Centre, University College London, Gower Street, London WC1E 6BT, U.K
| | - S J Cassidy
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - N H Rees
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - P Holdship
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, U.K
| | - R I Smith
- Rutherford Appleton Laboratory, ISIS Facility, Harwell Campus, Didcot, Oxon OX11 0QX, U.K
| | - B Zhu
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
- Thomas Young Centre, University College London, Gower Street, London WC1E 6BT, U.K
| | - D O Scanlon
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
- Thomas Young Centre, University College London, Gower Street, London WC1E 6BT, U.K
| | - S J Clarke
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
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Holmes GL, Chronopoulos A, Stafstrom CE, Mikati MA, Thurber SJ, Hyde PA, Thompson JL. Effects of kindling on subsequent learning, memory, behavior, and seizure susceptibility. Brain Res Dev Brain Res 1993; 73:71-7. [PMID: 8513557 DOI: 10.1016/0165-3806(93)90047-e] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To determine the long-term effects of seizures on the developing brain we kindled 20-, 40-, and 60-day-old rats to stage 5 seizures and then elicited an additional 15 seizures using the same kindling stimulation. At age 80 days, all animals that reached stage 5 kindling, and their respective age-matched controls, underwent behavioral testing using the Morris water maze, open field test, and handling test. Prior to euthanasia the animals had seizure threshold tested using flurothyl inhalation. No differences were noted in time to platform in the water maze or activity level in the open field test between the kindled rats and controls in any of the three age groups. Rats kindled at age 20 and 40 were more emotional than the controls in the handling test. In the flurothyl inhalation test, rats kindled at 40 and 60 days of age had a shorter latency to all seizures stages than the controls. These results demonstrate that while kindling results in no alteration of learning, memory, or activity level, it does result in altered emotionality and activity level in immature animals, as well as reduced seizure threshold in pubescent and mature rats. The animal model used appears to be an important variable in determining the long-term effects of seizures.
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Affiliation(s)
- G L Holmes
- Department of Neurology, Harvard Medical School, Children's Hospital, Boston, MA 02115
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