Abstract
SrSiO3 decomposes to Sr2SiO4+SrSi2O5 phases at about 11 GPa. An X-ray diffraction pattern of the SrSi2O5 phase has not been reported yet among silicate minerals. Therefore, a high-pressure synthesis of the SrSi2O5 phase was performed at 16 GPa and 900 degree C. Then X-ray diffraction profile of the synthesized sample was measured. A Rietveld analysis of the obtained XRD profile was made by using the crystal structure of BaGe2O5-3 as model.The lattice parameters were determined to be a=5.2389(1) A, b=9.2803(2) A, c=13.4411(2) A with the space group Cmca. A basic structure consists of layer frame of SiO6 and SiO4 polyhedra with corner sharing. Strontium site places between the layer frames, and is oxygen twelvesfold. The average Sr-O distance is 2.729 A. That shows the obtained crystal structure is able to accomodate a relative large cation.
