Study on phase transition of SrTiO3 by in situ impedance measurement under high pressure

The pressure dependence of electrical resistance of perovskite SrTiO3 has been studied by in situ impedance measurement in diamond anvil cell up to 31 GPa at room temperature. Two discontinuous changes in resistance were observed at about 9.8 and 21 GPa, which are coincident with the pressure-induced phase transitions from cubic phase to tetragonal phase and then to orthorhombic phase, respectively. High-pressure angle dispersive X-ray diffraction experiments on SrTiO3 powders have also been performed up to 35 GPa. It was found that a structure phase transition from cubic to tetragonal phase begins to take place at about 6.49 GPa but clear indication for a further transition to an orthorhombic phase at higher pressure up to 35 GPa is hardly seen in our X-ray diffraction data. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim