Pressure-induced structural and vibrational evolution in ferroelectric RInO3 (R=Eu, Gd, Dy)

The structural and vibrational properties of the hexagonal indates RInO3 (R=Eu, Gd and Dy) have been studied under high pressures using synchrotron x-ray diffraction and Raman scattering in diamond anvil cells. The three hexagonal structures exhibit anisotropic compression behaviors under high pressures and are stable up to ~17 GPa. High-pressure Raman spectra show that most frequencies harden linearly with different rates under high pressures. At ~17 GPa, three compounds undergo similar phase transitions. It is hard to indentify the structure of the high-pressure phase due to the broad x-ray diffraction and Raman patterns which could result from the kinetic hindrance of the phase transition at room temperature.