The new structure transition sequences of cerium around 5Â GPa

- The fcc′→C2/m →α-U→bct transition of Cerium is clearly observed at high pressure.
- The growth of grains in α-U structure is driven by the phase interface mismatch of α-U and fcc′.
- Prepressed condition is a feasible method for the phase transition research at high pressure.
- The high pressure crystal structures of Cerium are confirmed by full Rietveld refinement.

A fascinating structure transition of cerium around 5 GPa has been studied using high-resolution synchrotron angle-dispersive powder diffraction techniques. This study indicates that the structural transition of cerium strongly depends on the process of compression. Two runs experiments with different compression conditions demonstrate two different structural transition sequences at room temperature around 5 GPa, fcc′→C2/m →bct for regular compression, fcc′→C2/m →α-U→bct for the pre-compression. These results show that pressure is not the only factor to determining structural transformation at high pressure, and the structural transformation sequences can be varied by changing the external conditions e.g. pre-compression.