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 Nd2Ti2O7 compound. The structural and vibrational properties of a layered Nd2Ti2O7 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 P21 C22 phase to the monoclinic P2 C21 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 TiO6 octahedra, alterations in interatomic distances, and the displacement of Nd atoms were discussed.