A ferroelectric barium titanate, BaTi2O5

The crystal structure of monobarium dititanium pentaoxide, BaTi2O5, synthesized by a floating-zone method, was studied by X-ray diffraction. Previous reports describe the structure as being in the monoclinic centrosymmetric space group C2/m. We have recently found that this material exhibits ferroelectricity, and therefore BaTi2O5 should have lower symmetry. The crystal structure of BaTi2O5 was refined in space group C2, revealing a displacement of the Ti atoms along the b axis. This result is consistent with the fact that the ferroelectricity of BaTi2O5 was only observed along the b axis.