CUXY COMPOUNDS AS THIN-FILMS - CRYSTALLOGRAPHIC AND COMPOSITIONAL ANALYSES OF YTTRIUM RICH PHASES

The interdiffusion of Y films deposited onto Cu substrate by flash eva poration and sputtering was studied (concentration profiles, X-ray and electron diffraction patterns) in the temperature range 373-553 K. In samples deposited by Bash evaporation the first phase to be detected is CuY at 393 K. At higher temperatures an intermediate phase, close t o the Cu3Y2 compound, is formed before the Cu2Y stoichiometric phase i s produced at 513 K. Crystallographic data confirm the formation of th is intermediate Cu3Y2 phase (orthorhombic unit-cell) as resulting from the reaction CuY+Cu2Y-->Cu3Y2. The results are identical for sputtere d Y films deposited under a cryogenic vacuum (2-5X10(-7) Pa). When Y i s deposited under a standard vacuum (2-5X10(-6) Pa), the influence of a diffusion barrier at the Cu-Y interface is noticed. This influence i s characterized in the concentration profiles by an Y concentration hu mp at the Cu-Y interface and a depletion of Y at the front of the prof ile. Three main phases are observed. They correspond to the Cu5Y2, Cu2 Y and Cu3Y2 compounds. (C) 1998 Elsevier Science S.A.