Pressure-Iduced Phase Transition of LiAl5O8

A phase transition concerning lithium aluminate oxide (LiAl5O8) was observed. High pressure synchrotron radiation X-ray diffraction was used to explore its structure in a diamond anvil cell up to 47.0 GPa. We found the two phases are coexisted over a very large pressure range in the experiments. According to the analysis on the dynamic change of diffraction peaks with the increasing of pressure and the data reduction using indexed program, a new high-pressure phase of LiAl5O8 was identified at pressure below 45.0 GPa. This new phase has potentially a orthorhombic structure with a=0.995 9 nm, b=0.644 7 nm, c=0.333 4 nm and the space group of Pmm2.