Structural behavior of Sr2Bi2O5 at high pressures

The structure of Bi2Sr2O5 at high pressures is investigated by in situ X-ray diffraction (XRD) and Raman scattering methods. Raman results indicate that there are two pressure-induced phase transitions that occurred at ∼1.4 and ∼11 GPa, respectively. XRD measurements reveal only one high-pressure phase, which is indexed with a monoclinic unit cell and the possible space groups are P121(No. 3), P1m1(No. 6) and P12/m1(No. 10). The phase transition above 11 GPa is probably due to the symmetry change without discontinuity of the unit cell. The high-pressure phase is quenchable and it is a new dense form and about 11% denser than the normal orthorhombic Bi2Sr2O5 at room conditions.

Pressure dependence of the frequency of the observed Raman modes for orthorhombic Bi2Sr2O5 clearly indicates the phase transition.Figure optionsDownload as PowerPoint slide