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Dalton Transactions, 49, 13663-13670 , (2020) [doi: 10.1039/D0DT02721A]

High pressure exploration in the Li–Ln–V–O system

A. Zadoia, A. Arevalo Lopez, J. Sánchez-Benítez, M. Huvé, J.-F. Blach, S. Merkel, N. Hilairet, J. Chantel, M. Colmont

Using in situ high pressure Raman spectroscopy{,} two structural changes were observed in a sample of the composition LiLa5O5(VO4)2. Taking this into account and by combining different conditions{,} three new compounds were further obtained from high pressure–high temperature synthesis. Their crystal structure description was done using the antiphase approach{,} which implies the presence of oxygen-centered [OLn4] building units{,} where Ln is La for (1) β-LiLa5O5(VO4)2 and (2) β-LiLa2O2(VO4) or Nd for (3) LiNd5O5(VO4)2 compounds. (1) crystallizes in the triclinic space group P̄ with unit cell parameters of a = 5.8167(15) Å{,} b = 12.2954(28) Å{,} c = 18.7221(69) Å{,} α = 102.03(2)°{,} β = 98.76(2)°{,} and γ = 103.54(2)°; a 3D structure was deduced from the ambient pressure polymorph. (2) also crystallizes in P̄ with a = 5.8144(7) Å{,} b = 5.8167(7) Å{,} c = 8.5272(1) Å{,} α = 98.184(7)°{,} β = 100.662(7)° and γ = 92.579(7)°. It shows a 2D structure with [La2O2]2+ layers surrounded by [LiO4] and [VO4] tetrahedra sharing corners and edges. (3) exhibits a 3D architecture isotypic with AP-LiLa5O5(VO4)2. The crucial role of high pressure in such types of synthesis and materials is also discussed.

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© Sébastien Merkel, Université de Lille, France

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