Extended x-ray absorption fine-structure investigation ofNb3Ge films

Abstract

We have studied the extended x-ray absorption fine structure (EXAFS) on the Ge K edge in Nb/sub 3/Ge (A15 structure) films with samples prepared by the chemical-vapor-deposition and e-beam coevaporation techniques and having different superconducting transition temperatures. For the e-beam samples, our EXAFS experiments confirm the existence of two phases, one of which is quasiamorphous with smaller atomic separations and average coordination number than the A15 phase. The additional temperature dependence of the fluctuations in the nearest- (and further)-neighbor distance agrees with expectations from the phonon spectrum determined by other methods. No effect of any lattice transformation between 77 and 573 K was obtained.