Pressure-temperature phase diagram of multiferroic EuTiO3

The structural transformation of multiferroic EuTiO3 has been intensively investigated by synchrotron x-ray diffraction at pressures up to 50.3 GPa and temperatures from 50 to 500 K. A pressure-induced antiferrodistortive phase transition from cubic Pm (3) over barm to tetragonal I4/mcm space group has been observed, identical to the one that has been previously explored at ambient pressure and low temperatures. Several compression/decompression cycles at different temperatures have been carried out to accurately map the transition, and as a result a P-T phase diagram for EuTiO3 has been constructed. The observed phase transition exhibits a positive dP(c)/dT (P-c being the critical pressure of the transition) and has many similarities with isostructural SrTiO3, although the absence of magnetoelectric interactions in the latter accounts for the different phase boundaries between the two materials.