X‐ray diffuse scattering from a nitrogen‐implanted niobium film

A 2500-angstrom niobium single-crystal film was deposited onto a sapphire substrate and subsequently implanted with nitrogen to an average concentration of 0.5 at. %. Synchrotron radiation was used to measure the difference between the implanted and an unimplanted film to isolate the diffuse scattering from the implanted film near two Bragg reflections. This diffuse intensity arises mainly from elastic displacement fields about radiation-damage-related loops located on (211) planes. A small contribution of the scattering is calculated from the displacements about single interstitial nitrogen in octahedral sites. The Burgers vector of the loops is along the [111BAR] direction and makes an angle of 62-degrees with the loop plane giving a dominant shear component. Vacancy loops have a radius approximately 5 angstrom while interstitials are somewhat larger ranging from 10 to 15 angstrom. The number of vacancies and interstitials are nearly the same.