The crystal structure of Rb2Ti2O5. Issue 6 (11th December 2017) - Federicci, Rémi
Abstract : Structural investigation of Rb2 Ti2 O5 was carried out using X‐ray diffraction, Raman spectroscopy along with calculations of phonon modes using DFT. Abstract : Recent results have demonstrated an exceptionally high permittivity in the range 200–330 K in crystalline titanium oxide Rb2 Ti2 O5 . 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 density functional theory calculations. These important findings allow the existence of a conventional ferroelectric phase transition to be ruled out as a possible mechanism for the colossal permittivity and polarization observed in this material.