At present, the Laue method is mostly utilized to identify the crystallographic orientation of fixed single crystals or wafers.
Unlike a conventional powder diffraction experiment in Laue diffraction, white Bremsstrahlung is used instead of monochromatic radiation. A 2D detector captures the signals that show up as arched arrays of reflections.
X-rays are diffracted by each set of lattice planes with a wavelength that obeys Bragg’s law. The use of white Bremsstrahlung makes the wavelength of the diffracted radiation unknown for each set of reflections; therefore, indexing of the signals becomes challenging.
Back-Reflection Laue Method
In the back-reflection technique, the 2D detector is positioned between the crystal and the X-ray source. The backward diffracted radiation is detected when it intersects the detector.
The cone of Laue reflections is defined by the converted beam, where the cone usually looks like a hyperbolic shape upon intersecting the detector.
Schematic diagram of a diffraction assembly by the Laue method Thermo Scientific ARL EQUINOX LAUE.
Features
The Thermo Scientific™ ARL™ EQUINOX LAUE X-ray diffractometer (XRD) is an economical solution to fulfill all needs in both academic and industrial research laboratories, as well as QA/QC or operations facilities.
- Complete 3-kW power instrument, W or Mo wavelength
- Motorized sample positioning
- Back-reflection 2D camera
- Sample positioning by a camera
- Built-in beam collimation
- The manually operated goniometer head can be directly transferred to a wire saw
Camera Specifications
The high-resolution Thermo Scientific™ ARL™ EQUINOX LAUE camera can be used to record digital Laue diffraction pattern with 14-bit digitization and a resolution of 2774 x 1843 pixels.
The X-ray beam that passes through the camera is collimated. The active area input dimension is analogous to that of a Polaroid film, which is 156 mm x 104.4 mm. At the time of crystal orientations, exposures from a few seconds up to >30 minutes can be tuned, before being cut for example.
Applications Fields
The ARL™ EQUINOX LAUE is a flexible XRD instrument that can be used for determining crystal orientation such as wafer, ingots, jewelry, precious stones, turbine blades, etc.
Examples of crystals: Al2O3, KTP, YAG, CdTe, Tungsten, Quartz, LiF, CaF2, etc.
- High-intensity white radiation enables rapid data acquisition
- Quick collection of Laue patterns of separate crystals
- High information density in Laue pattern achieved through multi-diffraction
- High-energy radiation results in large measured volume owing to high penetration depth
Thermo Scientific™ ARL™ EQUINOX LAUE.
Diamond Crystal
- This diamond crystal is a piece of cut fashion jewelry (measuring a few cubic millimeters).
- The dots are well-defined and the orientation is (111).
Diamond on Earring
- With the help of a video camera, it is feasible to adjust a crystal and then measure it in Laue XRD. The size of the gem is approximately 2 mm.
- The Laue pattern depicts the (100) axis of the diamond, illustrated by the four-fold symmetry.
Fluorine Crystal
- A fluorine crystal (employed for laser emission) is produced and placed on a goniometer head, which is compatible with the ARL™ EQUINOX LAUE and a wire saw.
- Thus, after accurately identifying the (111) direction through Laue measurements, direct cutting of the crystal can be performed.
Quartz Resonator
- The electrical contacts are visible on each side of the image. The crosshair denotes the place of the X-ray beam.
- A quartz resonator is a single crystal that can vibrate along a crystallographic axis when an oscillating voltage is applied.
