An x-ray diffraction reciprocal spacing mapping (RSM) technique was applied to investigate crystal\r\nquality of Nb films and bulk materials, relevant to superconducting radio frequency applications. The\r\nRSM study used different x-ray penetration depths to study material processes after two different surface\r\ntreatments: mechanical polishing or energetic condensation (a plasma process). The study revealed the\r\nmaterialâ��s microstructure evolution for the two different processes. The RSM plots revealed crystal quality\r\nof the materials at different thickness. The novel, differential-depth RSM technique presented in this study\r\nsubstantiated the following facts: (1) For a heteroepitaxial Nb film Nb�°100�ž=MgO�°100�ž, a film thickening\r\nprocess, via a cathodic arc-discharge Nb ion deposition (energetic condensation), created a near-perfect\r\nsingle crystal Nb on the surface top layer. (2) For a fine mechanically polished single-crystal bulk Nb\r\nmaterial, the microstructure on the top surface layer is more disordered than that at a greater depth.
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