The crystal structure of Rb2Ti2O5

Rémi Federicci (1) , Benoit Baptiste (2) , Fabio R.D. Finocchi (3, 4) , Florin Popa (5) , Luc Brohan (5) , Keevin Béneut (2) , Paola Giura (6) , Gwenaelle Rousse (7) , Armel Descamps-Mandine (8) , Thierry Douillard (9, 10) , Abhay Shukla (6) , Brigitte C. Leridon (11)

1 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
2 IMPMC - Institut de minéralogie et de physique des milieux condensés
3 INSP - Institut des Nanosciences de Paris
4 INSP-E9 - Oxydes en basses dimensions
5 IMN - Institut des Matériaux Jean Rouxel
6 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
7 CSE - Chimie du solide et de l'énergie
8 Centre Castaing - Centre de microcaractérisation Raimond Castaing
9 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
10 CLYM - Consortium Lyon Saint-Etienne de Microscopie
11 Elemag

Recent results have demonstrated an exceptionally high dielectric constant in the range 200 K-330 K in a crystalline tianium oxide : Rb 2 Ti 2 O 5. In this article, the possibility of a structural transition giving rise to ferroelectricity is carefully inspected. In particular X-Ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy are performed. The crystal structure is shown to remain invariant and centrosymmetric at all temperatures between 90 K and 450 K. The stability of the C 2/m structure is confirmed by DFT calculations. These important findings allow to discard the existence of a conventional ferroelectric phase transition as a possible mechanism for the unusual dielectric constant observed in this material.

Domaines: Matière Condensée [cond-mat]

Rémi Federicci, Benoit Baptiste, Fabio R.D. Finocchi, Florin Popa, Luc Brohan, et al.. The crystal structure of Rb2Ti2O5. Acta Crystallographica Section B : Structural Science, Crystal Engineering and Materials [2014-..], 2017, 73 (6), pp.1142-1150. ⟨10.1107/S2052520617013646⟩. ⟨hal-01985276⟩