A new reversible phase transformation of intermetallic Ti₃Sn

Ti₃Sn has received increasing attention as a high damping metallic material and as an anode material for rechargeable lithium-ion batteries. However, a heated dispute concerning the existence of solid state phase transformation of stoichiometric Ti₃Sn impedes its development. Here, thermal-induced reversible phase transformation of Ti₃Sn is demonstrated to happen at around 300 K by the means of in-situ variable-temperature X-ray diffraction (XRD) of Ti₃Sn powder, which is also visible for bulk Ti₃Sn on the thermal expansion curve by a turning at 330 K. The new phase's crystal structure of Ti₃Sn is determined to be orthorhombic with a space group of Cmcm and the lattice parameters of a = 5.87 Å, b = 10.37 Å, c = 4.76 Å respectively, according to selected area electron diffraction patterns in transmission electron microscope (TEM) and XRD profiles. The hexagonal→ orthorhombic phase transformation is calculated to be reasonable and consistent with thermodynamics theory. This work contributes to a growing knowledge of intermetallic Ti₃Sn, which may provide fundamental insights into its damping mechanism.