A structural phase transition in the intermetallic compound Tm3Cu4Sn4

The ternary intermetallic system R3T4X4 (where R = rare earth; T= Mn, Cu, Ag, Au, Pd; X=Si, Ge, Sn) comprises an extensive series of isostructural compounds that form in the orthorhombic Gd3Cu4Ge4-type structure (space group Immm, no. 71). The exceptions to this generic structure are Tm3Cu4Sn4 and Lu3Cu4Sn4 which have a monoclinic structure (space group C12/m1, no. 12) at room temperature. Here, we report a structural phase transition in Tm3Cu4Sn4 from monoclinic C12/m1 to orthorhombic Immm upon heating above room temperature. We have carried out X-ray powder diffraction and differential scanning calorimetry on Tm3Cu4Sn4 and we observe the structural transition at 458(2) K.