The use of through focus exit wave reconstruction in the structure determination of several intermetallic superconductors

The feasibility of the use of the through focus exit wave reconstruction method to determine structures of inorganic compounds is investigated. To illustrate the potential of the method recent structure determinations of several intermetallic compounds, e.g. YPd₂B₂C, LuNiBC, Lu₄Ni₂B₃C₄ and ThPd(x)B(6-2x) are discussed. It is shown that combination of the amplitude and phase information of the exit waves at various specimen thicknesses allows one to determine the positions of all atoms. Whereas the light atoms can be best distinguished in the phase image of a somewhat thicker part of a crystal, the heavy atoms can be observed most reliably in the amplitude part. In particular the change of the exit wave with thickness was found to be very useful in the determination of the presence of light atoms.