Preparation of thin foils for transmission electron microscopy from hydrogenated intermetallic compounds

Abstract

A preparation method has been developed for thin foils for transmission electron microscopy (TEM) from powdered intermetallic compounds as a result of hydrogenation, in which powder samples are embedded in a Ni plate formed by electroless plating and then the assembly consisting of the Ni plate and the embedded powder samples are ion-milled. This method is successfully applied to some typical hydrogen-absorbing intermetallic compounds such as LaNi 5, FeTi and TiMn 2. In this method, Ni plating is carried out at ambient temperature, at which possible rearrangement of lattice defects that are introduced during hydrogenation is minimized and areas thin and wide enough for TEM observations are successfully produced because of the small difference in the sputtering yield between the Ni plate and these intermetallics. For thin foils produced by this method, not only lattice defects such as dislocations introduced into the bulk of powder samples can be characterized but also the crystallography of cracking and surface layers of powder samples can be characterized.