X-ray Diffraction On ZnO, SiC Thin Films And Micro-beam Scattering On Polymer Systems

X-ray diffraction is one of the most important methods for structure analysis. Based on the X-Ray Diffraction and Scattering(XRDS) Station in National Synchrotron Laboratory(NSRL) in Hefei, China and D-line in Cornell High Energy Synchrotron Source(CHESS), several techniques of diffraction were developed, including of Grazing Incidence Diffraction(GID), Asymmetric Diffraction, Micro-beam Small Angle X-ray Scattering(μSAXS), and Micro-beam Grazing3 Incidence Wide Angle X-ray Scattering(μGIWAXS). And some thin films were investigated, including of ZnO, SiC thin films as semiconductor material and PI-b-PEO/resol complex, P3HT micron-wire as polymer material. At last, X-ray Magnetic Circular Dichroism (XMCD) was employed on Fe and Co nano ferromagnetic thin films. The main works are shown below.1. Building up of the beamline and station of XRDS in NSRLI was involved in the construction of the beamline and station, which were described here on the construction, facilities and performance. The focusing mirror and monochromter as the important facilities in the beamline were introduced detailed. Many new applications were developed in material science, including of the X-ray Reflectivity on the Si/C multilayer, the powder diffraction on the standard Si sample, the scattering from quasiperiodic structures in relaxor ferroelectrics, the structure of single crystal in insoluble coordination polymer and so on.2. Investigations of the ZnO and SiC thin films by multi diffractionsThe ZnO and SiC semiconductor thin films were investigated by GID and asymmetric diffraction. ZnO films, made in several series by Pulsed Laser Deposition (PLD), were investigated by GID for the lattice relaxation and interface structure in different depth. One series are the ZnO/Si with and without the SiC buffer layer, the other series are the ZnO/Al₂O₃ made in different temperatures and oxygen concentrations to look for the film with the best quality. The asymmetric diffraction was used to show the difference of orientations and density of screw and edge dislocations between the ZnO/Al₂O₃ and ZnO/SiC films. The correlation between the tilt and twist mosaics were also shown. Besides, the CCD detector was join into the GID and the different orientation and crystal quality were shown in a series of ZnO/Si(111) films with different temperatures. For the SiC films made in Molecular Beam Epitaxy (MBE), the GID was employed in the homoexpitaxy films to obtain the three layer structure model in the interface. Also, lattice relaxation and interface structure in different depth were shown in hereoepitaxy SiC/Si films. At last, the results from the asymmetric diffraction indicated the orientation of the SiC/Si film and the correlation between the tilt and twist mosaics.3. Investigations of the polymer material by the microbeamIn the D-line, CHESS, the single-bounced capillary was used to obtain the micron-sized beam (about 15μm) with the high flux (about 1×10¹⁰photons/s), low divergence (lower than 2 mrad) and 50nm resolution. The character of the microbeam was shown after the introduction of the line-up process. The PI-b-PEO/resol complex was characterized by the Microbeam Small Angle X-ray Scattering (μSAXS) and there are two kinds of grains with different size and structure. The details of the structure are obtained, including of the size, lattice, orientation and crystalline degree. For the P3HT microwire, the Microbeam Grazing Incidence Wide Angle X-ray Scattering (μGIWAXS) was employed to construct the structure model and distinguish the difference of orientations in the surface region, interface region and center region. The width of the microwire was shown from the beam scan and the orientation changing of the P3HT packing following with the round surface in the surface region was observed in the first time.4. XMCD effect in the nano-ferromagnetic thin filmsOn the X-ray Magnetic Circular Dichroism (XMCD) station in NSRL, the soft X-ray was obtained with the energy range of 100-1000eV, resolution of 1000 in 1000eV and high flux (more than 10⁸photons/s), and used in the conductor and semiconductor thin films. We investigated the XMCD effect in the Fe/MgO and Co/Au nano-ferromagnetic thin films. For the Fe/MgO film, the spin and orbital magnetic moments of the iron atoms were 0.069μ_B and 2.33μ_B, respectively. Compared with the different orbital magnetic moments in three orientations, [110], [100] and [010], the magnetic anisotropy on the surface is shown as the two-axis and one-axis anisotropic energy roughly equally. The series of the Co/Au films with different thickness are shown with magnetic moments. With the decrease of the 30nm, 10nm and 2nm thickness, the orbital magnetic moments are increased in the range of 0.195--0.249μ_B as the spin magnetic moments decreased in the range of 1.734--1.230μ_B. It means the ratio of the orbital and total magnetic moments are increased remarkably from 0.101 to 0.168.