Superconductivity of Crystallized Phases from Amorphous La80Al20

In this paper, we studied the structures and superconductivity of the samples annealed from a morphous La80Al20 alloy under different treatments. It was found that when annealed in vacuum at 250 ℃, the a morphous alloy crystallized into the sample of a tetragonal single phase La4Al for which where is no TC as T4.2 K. When annealed in vacuum at 300 ℃, or 450 ℃, the amorphous samples crystallized into the samples of hexagonal La3Al, -La, -La and some unknown phases, the TC ofthese multiphase samples is lower than 6.0 K. When annealed under 6 GPa, if annealing temperature Ta300 ℃, the amorphous alloy crystallized into the sample of hexagonal La4Al, the parameters of which are exactly the same as hexagonal La3Al and TC of which is lower than 5.7 K; if Ta350 ℃, the amorphous alloy crystallized into the sample of hexagonal La3Al and a unknown phase H, the TC of new phase H is 6.3 K.