9704210 Streiffer This award provides partial support through the Division of Materials Research and the office of Multidisciplinary Activities for the acquisition of a multiuser, four-circle x-ray diffractometer equipped with parabolic condensing mirrors and an x-ray area detector. Such an instrument presents the opportunity to perform significant novel, nontraditional characterization of a wide variety of materials because of its configuration. This instrument will benefit faculty and students in Materials Research, Nuclear Engineering, Physics, and Chemical Engineering, and will provide training for students. First, four rotation axes allow a sample to be arbitrarily positioned in real space using three axes, while the diffracted radiation distribution is scanned with the fourth axis. The ability to orient a sample in three dimensions has become crucial as increasing physical anisotropy is routinely engineered into bulk specimens and thin films, and as more single-crystal-like materials are used in a wide range of applications. Second, parabolic, graded multilayer x-ray optical elements allow collection of Cu, Ka radiation from a wide acceptance angle followed by conversion into a parallel beam. The concomitant increase in intensity relative to flat crystal optics along with a beam divergence intermediate between that of parafocusing or slit optics and that of multi-bounce monochromators yields a collimated, parallel beam that is ideally suited for experiments performed on highly-oriented, but not epitaxial, materials, and for experiments utilizing very low incident beam angles, namely glancing incidence x-ray scattering and small angle x- ray scattering. Third, area detection of the scattered radiation facilitates examination of large areas of reciprocal space in an extremely time-efficient manner. This is of paramount utility for any case in which there is complicated reciprocal space structure. As examples, area detection great ly simplifies the collection of pole figures from textured materials and the determination of diffraction peak shapes for complex microstructures. This equipment is required to fulfill the general need for advanced characterization in materials science and engineering. Current materials research programs will be significantly impacted by the proposed instrumentation. These include: (i) structural characterization of multicomponent oxide thin films and heterostructures; (ii) investigation of complex morphologies in block copolymers; (iii) characterization of semiconductor thin film heterostructures; (iv) investigation of the effects of texture on creep, deformation, fracture, and degradation of metals and alloys targeted for use in aggressive environments, and (v) phase identification, microstructure determination, and investigation of transformations in nanosized powders and powder composites. There is great scientific and commercial interest in each of these areas, and the capabilities provided by new diffraction instrumentation will significantly extend the scientific contribution obtained from existing funding sources. Finally, the importance of access to state-of-the-art methodologies, as will be provided by such a diffractometer, is emphasized for both graduate and undergraduate training. ***
