Compressibility and phase transition of intermetallic compound Fe2Ti

The structural stability of Fe2Ti (P63/mmc) has been investigated by synchrotron radiation X-ray diffraction with diamond anvil cell. At room temperature, Fe2Ti shows a monotonous change of unit-cell volume in present pressure range up to 40.3 GPa. Isothermal pressure–volume relationship of Fe2Ti (P63/mmc) is well described by the second order Birch–Murnaghan equation of state with V0 = 161.8(3) Å3 and B0 = 201(4) GPa. A new polymorph of Fe2Ti indexed to an orthorhombic phase is observed when the sample undergoes the high-temperature annealing using laser heating at 46.6 GPa. This orthorhombic phase can be quenched and preserved on decompressing to ambient pressure.

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► High pressure structural stability of Fe2Ti (P63/mmc) was investigated.
► Fe2Ti is stable up to 40.3 GPa at room temperature.
► Axial compressibility presents obvious anisotropy.
► A new orthorhombic phase of Fe2Ti was observed after laser heating.
► This orthorhombic phase can be quenched and preserved on decompressing to ambient pressure.