Potassium– and lithium–ammonia intercalation into excitonic insulator candidate Ta2NiSe5

Journal article

Two new reduced phases derived from the topical excitonic insulator candidate Ta₂NiSe₅ have been synthesized via the intercalation of lithium and potassium from solutions of the metals in liquid ammonia. Li(NH₃)Ta₂NiSe₅ and KTa₂NiSe₅ both crystallize in orthorhombic space group Pmnb with the following lattice parameters: a = 3.5175(1) Å, b = 18.7828(7) Å, and c = 15.7520(3) Å and a = 3.50247(3) Å, b = 13.4053(4) Å, and c = 15.7396(2) Å, respectively. They have increased unit cell volumes of 48% and 31%, respectively, relative to that of Ta₂NiSe₅. Significant rearrangement of the transition metal selenide layers is observed in both intercalates compared to the parent phase. In Li(NH₃)Ta₂NiSe₅, neutron diffraction experiments confirm the location of the light Li, N, and H atoms, and solid-state nuclear magnetic resonance (NMR) experiments show that H, N, and Li each occupy a single environment at ambient temperature on the NMR time scale. Magnetometry data show that both intercalates have increased magnetic susceptibilities relative to that of Ta₂NiSe₅, consistent with the injection of electrons during intercalation and an enhancement of the Pauli paramagnetism.

Authors: Hyde, PA; Avdeev, M; Rees, NH; Clarke, SJ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Chemistry of Materials
• Volume: 36
• Issue: 19
• Pages: 9939-9946
• Publication date: 2024-09-20
• Acceptance date: 2024-09-10
• DOI: 10.1021/acs.chemmater.4c02155
• EISSN: 1520-5002
• ISSN: 0897-4756
• Language: English
• Keywords: diffraction; intercalation; layers; nuclear magnetic resonance spectroscopy; potassium