This is a state-of-the-art machine including a Vantec-500 area detector, centric 1/4-circle Eulerian cradle, domed hot stage, hi-flux in-plane hardware, laser/video sample-alignment system, Göbel mirror, fine tilt stage, and dual-beam path analyzer module. The system can be configured for grazing-incidence in-plane XRD, grazing-incidence XRD, x-ray reflectivity, high-temperature XRD, high-resolution XRD (rocking curves, reciprocal space maps), texture (pole figures), residual stress, and capillary diffraction. Bruker D8 Discover diffractometer is configured in parallel beam geometry with Cu Kalpha radiation (wavelength of about 1.54 Å).
Featured Hardware
- Vantec 500 area detector:
A large-area, high-sensitivity, 2-dimensional detector based on MikroGap technology allows the collection of a large quantity of 2-dimensional information quickly. - Centric 1/4-Circle Eulerian Cradle
Sample positioning: motorized Chi(tilt) and Phi(rotation) rotations and X-Y-Z translations. The cradle accommodates bulky specimens, powders, thin films, and wafers up to 80 x 50 x 20 mm and weighing up to 1 kg. - Domed hot stage
A heating device with an x-ray transparent dome designed for orientation-sensitive temperature studies from room temperature to 900 °C in air, vacuum, or inert gas atmosphere. It allows access to the entire diffraction space of a sample when measuring in reflection mode. - Hi-flux in plane hardware:
Unique hardware allows the x-ray tube to be rotated such that the line focus is in the scattering plane of the instrument, which produces very high diffracted intensities when in the grazing incidence in-plane diffraction geometry. Motorized tube movement out of the diffractometer scattering plane allows accurate setting of incident angle. - Laser/video Sample alignment System:
Computer-controlled video camera and laser pointer for easy and accurate sample positioning and system alignment. - Göbel Mirror
A parabolic, laterally graded multilayer mirror that converts the divergent beam projected by the line focus of an x-ray tube into a quasi-monochromatic and highly parallel (divergence .03°) beam of high intensity. White radiation and Kα lines are virtually eliminated. - V-Groove Ge crystal monochromator
Using the Göbel mirror as a beam conditioner, this channel-cut 2-bounce Germanium monochromator yields an extremely parallel (divergence .007°) and monochromatic (only Cu Kα1) beam for high-resolution applications. - Fine Tilt stage
A motorized tilt stage for sample pre-alignment allows tilting a sample around 2 perpendicular axes, which allows the orientation of the sample normal to coincide with the Phi-circle of the Eulerian cradle. - Dual Beam Path analyzer module
A motorized module that allows software-controlled switching between 2 diffracted-beam configurations. The first is a high-intensity path incorporating a motorized slit, and the second is a high-resolution path incorporating a triple-bounce channel-cut monochromator.
Possible Applications
- Grazing Incidence In-Plane XRD (GIIXD)
In-plane diffraction is a technique for measuring the crystal planes that are oriented perpendicular to the surface. As a result, the in-plane lattice parameters and crystal orientation can be determined. - Grazing Incidence XRD (GIXD)
Enhance diffracted signal from polycrystalline thin films and examine structural variations as a function of depth by precisely controlling incident angle and therefore the penetration depth of x-rays. - X-Ray Reflectivity (XRR)
Measures film thickness, roughness (interface and surface), and density of films (2 nm – 500 nm). Also measures multilayer interface quality and periodicity structure evaluation. - High-temperature, orientation-sensitive XRD
Temperature-induced phase transition investigations, texture measurements, stress, profile analysis, powder diffraction, grazing incidence, and high-resolution studies. A point detector can be used for high resolution, and an area detector can be used for high speed. - High-Resolution XRD (HRXRD)
Rocking Curves This method analyzes epitaxial structures for which the layer and substrate are almost perfect single crystals. This means the difference in diffraction angle for the layer and substrate is very small and requires the capability to resolve Bragg peaks on an arc second scale. The data is recorded as a rocking curve and can be modeled and fitted to reveal structural details of the epitaxial layer.
Reciprocal Space Maps This technique analyzes epitaxial (and similar) thin films. Narrow scans of reciprocal lattice points are performed for various diffractometer settings, and the scattered intensity can be plotted in a 2-dimensional frame. - Texture (pole figures)
A pole figure is measured at a fixed scattering angle (constant d spacing). It consists of a series of Phi-scans (in-plane rotation around the center of the sample) at different tilts or Chi angles and measures preferred crystallite orientation. Measurement times are much faster when using the Hi-Star area detector. - Residual stress
Stress is determined by recording the angular shift of a given Bragg reflection as a function of sample tilt (psi). This provides a measure of strain in the sample from which the stress can be calculated by plotting the change in d-spacing against sin2psi. This measurement is faster and more accurate when calculations are based on the distortion of the entire Debye ring, which is possible when using the Hi-Star area detector. - Microdiffraction and capillary diffraction
Small sample amounts and/or samples that tend to have texture can be prepared in thin glass capillaries. A fast, reliable diffraction pattern can be acquired when the signal is detected over a large portion of the solid angle with an area detector. Small areas on larger samples can be probed using this method with the laser/video sample alignment and sample positioning of the Eulerian cradle.