Materials Research Laboratory

Philips X'pert MRD

Location
148 Materials Research Laboratory

Two state-of-the-art modular "Xpert" XRD systems from Philips have been installed at the CMM at the Materials Research Laboratory (lab room 148). This system has multi modular primary and secondary optics in order to account for the various requirements of primary x-ray beam divergence and detector angular acceptance. A Cu source with possibilities of line or point focus is used. In the high-resolution mode, a 12 arc-sec angular divergence of the primary beam can be achieved by using a four-crystal Ge monochromator, allowing for the investigation of thin films and multilayered systems with high crystalline quality. A Guttman mirror is also available in the primary optics increasing the efficiency of primary beam, making it ideal for the investigation of diffuse scattering arising from defects in thin films. In addition, a three-bounce analyzer crystal can be placed between the sample and the detector in order to limit the detector acceptance to ~ 12 arc-sec. This configuration is ideal for a full mapping of the reciprocal lattice of the material allowing for a complete separation between strain variation effects and defect-related contribution to the diffracted intensities. Composition and lattice parameter variations within 10-5 can be determined, and effects as mosaicity, strain relaxation, curvature, layer tilt, etc., are easily separated. Finally, the system is also well suited for reflectivity measurements by probing diffraction intensities at glancing angles of incidence in order to quantify thin film thickness and interface abruptness. Primary and secondary optics of the instrument can also be interchanged to accommodate conventional texture, stress and phase identification analysis. In this case, a crossed-slit collimator primary beam optics and a secondary optics with flat-graphite and parallel plates can be used. A sample cradle, with Eullerian rotation and flexibility to accommodate different sample thickness and shapes, also allow for pole figure analysis and low-resolution reciprocal lattice mapping. Demonstration and training in this new XRD system can be scheduled by contacting Dr. Mauro Sardela at the CMM, phones 4-0547 (office number #370) or 3-1612 (lab), or by-email at sardela@illinois.edu