Identification of the tetragonal Nb5Ge3 phase in two-phase Nb-Ge superconducting films by electron diffraction

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Abstract
Magnetization studies of CVD Nb3Ge superconducting films had previously shown that the critical current density (Jc) significantly improved in the presence of a few volume percent of the tetragonal Nb5Ge3 phase. The presence of this tetragonal phase was previously determined by x‐ray analysis. In the present study, Nb‐Ge films containing the A‐15 Nb3Ge phase and the tetragonal Nb5Ge3 phase were examined by transmission electron microscopy (TEM), with a view to determine the size and distribution of the tetragonal phase in the microstructure. This paper describes a procedure by which the Nb5Ge3 phase could be identified in the microstructure using electron diffraction. The Nb5Ge3 particles were present at the grain boundaries as well as within the grains of the A‐15 matrix.