Browsing by Author "Ice, Gene E."

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    Residual strain gradients in a fully stabilized zirconia sample
    Hwang, Bing; Houska, Charles R.; Ice, Gene E.; Habenschuss, Anthony (American Institute of Physics, 1988-06-01)
    Polished and severely ground fully stabilized zirconia samples are examined using primarily x‐ray diffraction(XRD). The XRD (111) profile reflections from both samples were broadened asymmetrically compared to that of an annealed sample. The asymmetry results from a d‐spacing gradient extending from the free surface into undisturbed bulk material. There are two possible origins of this depth gradient, i.e., variations in residual strain or chemical composition. The latter is eliminated by means of x‐ray photoelectron spectroscopy which did not reveal a chemical gradient. d‐spacing profiles for both samples are obtained nondestructively using a trial and error fitting procedure. A maximum compressive strain of ∼4% is obtained at the surface of the ground sample which decreases gradually to zero at greater depths. The overall zone is ∼1–2 μm. A similar but smaller compressive zone is found in the polished sample which is followed by a zone of tension. The maximum compressive strain at the surface is ∼5% and the overall zone of residual strain is ∼0.1 μm.
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    X‐ray diffuse scattering from a nitrogen‐implanted niobium film
    Rao, Satish I.; Houska, Charles R.; Grabowski, Kenneth; Ice, Gene E.; Sparks, C. J. (American Institute of Physics, 1991-06-15)
    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.