ION IRRADIATION - A TECHNIQUE PROVIDING A CRITERION TO DISTINGUISH BETWEEN AMORPHOUS AND NANOCRYSTALLINE IN1-XPDX FILMS

In1-xPdx films with 0.2 less than or equal to x less than or equal to 0.75 have been prepared by vapour quenching at 4.2 K or 77 K, respecti vely. To test whether amorphous (a-) phases can be obtained in this wa y, the resistance behavior and the electron diffraction patterns of th e as-prepared and annealed films were studied insitu. For films with x =0.25 additional information could be acquired from their superconduct ing behavior. Combining these results one concludes that a-phases exis t for the compositional range 0.2 less than or equal to x less than or equal to 0.6, which are stable up to crystallization temperatures T-x within the range 250 K less than or equal to T-x less than or equal t o 420 K. Irradiation of the crystallized films at low temperatures (4. 2 K or 77 K with heavy ions (350 keV Ar+ or Kr+) leads to complete re- amorphization. For x=0.67 corresponding to InPd2 a nanocrystalline (n- ) phase is obtained by vapour quenching at 77 K as inferred from x-ray diffraction. At T-x=700 K, these n-films exhibit a drop of the electr ical resistance indicating the beginning of significant grain growth. After recooling, Kr+ bombardment at 77 K does not restore the high ele ctrical resistance of the as-quenched n-film. This result can be used as a criterion when studying quenched films with x=0.625 corresponding to In3Pd5. In this case, a resistance drop is found at T-x=600 K, but the diffraction techniques do not allow an uniquevocal distinction be tween amorphous and nanocrystalline. This becomes possible by low temp erature ion irradiation after annealing at T>T-x. The bombardment resu lts in resistance changes, which saturate well-below the value of the as-quenched sample implying nanocrystallinity for the latter. Based on this criterion, a 'phase'-diagram for quenched In1-xPdx is provided w ith 0 less than or equal to x less than or equal to 1 containing the n ewly detected a- and n-phases.