The effects of high pressure on the crystal structure and vibration spectra of layered perovskite-like Nd2Ti2O7.

We had investigated the pressure-induced phase transition phenomenon in the perovskite-like material Nd 2 Ti 2 O 7 compound. The structural and vibrational properties of a layered Nd 2 Ti 2 O 7 have been studied by means of X-ray diffraction and Raman spectroscopy at pressures up to 30 GPa. The gradual structural phase transition from the initial monoclinic P2 1 C 2 2 phase to the monoclinic P2 C 2 1 phase was observed at P ∼ 19 GPa. This pressure-induced phase transition is accompanied by anomalies in the pressure behavior of unit cell parameters and vibrational modes. The role of pressure application as a trigger for a significant rotation of the TiO 6 octahedra, alterations in interatomic distances, and the displacement of Nd atoms were discussed. • Structural and vibration properties of perovskite-like layered Nd 2 Ti 2 O 7 was studied at pressures up to 30 GPa. • The structural phase transition in Nd 2 Ti 2 O 7 was observed at P = 19.2 GPa. • The suppression of the ferroelectric phase of Nd 2 Ti 2 O 7 was discussed. • The bulk modulus of both phases were calculated. [ABSTRACT FROM AUTHOR]