INFLUENCE OF LOW TEMPERATURE HIGH PRESSURE AND HIGH TEMPERATURE HIGH PRESSURE TREATMENT ON STRUCTURE AND SUPERCONDUCTIVITY OF AMORPHOUS ALLOY La80Al20

The rapidly quenched La80Al20 alloy is amorphous. At atmospheric pressure, its crystallization temperature and glass temperature are ～280℃ and ～242℃ respec-tivily, according to DTA measurements. The superconducting transition temperature Tc increases from 3.87 to 4.18K, in the hydrostatic pressure range of 1-4770 bars, while its residual resistance decreases significantly. After high pressure-high temperature treatment (25kbar, ～160℃, 40 min), amorphous→crystalline transition of La80Al20 alloy occurs, as disclosed by X-ray diffraction method. The product consists of α-La phase and a new metastable phase, and its Tc increases from 3.9 to 5.7 K. Some preliminary discussion on the experimental results are also presented.