Crystallization, decomposition and superconductivity of β-In3Sn

The decomposition of β-In3Sn has been studied using both single crystals and polycrystalline samples. Spherical crystals of In3Sn up to 3 mm in diameter were obtained. The large crystals show laminar ribbons on the surface perpendicular to the [110] and [001] directions of the tetragonal space-centred lattice cell. Powder X-ray diagrams of the In3Sn alloy were made at 298 K and 223 K after both cooling and heating cycles. At 223 K the decomposition of the In3Sn alloy into β and γ phases and an unidentified phase is observed. The sample easily becomes homogeneous. The influence of the cooling rate on the magnetization of In3Sn was examined and the dependence of the lattice parameters on temperature is given. X-ray powder diagrams, lattice parameters and magnetization measurements prove that the decomposition of the β-phase depends strongly on the cooling rate and the structure of the sample. (Auth.)