Help with Diffractometers specifications:
Type
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| Wave Type | |||
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| Electron | Diffractometers use electrons to study crystal structures. | ||
| Gamma Ray | Diffractometers use gamma rays to study crystal structures. | ||
| Neutron | Diffractometers use neutrons to study crystal structures. | ||
| X-Ray | Diffractometers use X-rays to study crystal structures. These devices penetrate solids and ionizing gases with X-rays, electromagnetic radiation with wavelengths in the range of 0.1 to 10 nm. | ||
| Other | Other unlisted wave types. | ||
| Search Logic: | All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. | ||
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| Detector Type: | |||
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| Camera / Film | Laue, Debeye-Scherrer, Buerger Precession, Gunier and Weisenberg cameras use photographic film for the collection of X-ray diffraction patterns. Cameras are the oldest type of diffraction instrument, and their use has been largely supplanted by diffractometers. | ||
| Imaging Plate/Foil | Imaging plates or foils are a film-like radiation image sensor based on photo stimulated luminescence (PSL). These detectors are comprised of specially-designed phosphors that trap and store the radiation energy. This stored energy is stable until scanned with a laser beam, which releases the energy as a luminescence signal that is collected with a photodetector (e.g., photomultiplier tube). | ||
| Position Sensitive Detector (PSD) | Position sensitive detectors (PSD) are a type of proportional counter that uses gas ionization and a localized electron avalanche process to amplify the signal from the detected X-ray. Both linear (1D) and area (2D) type PSDs are available. Linear PSDs use a fine wire to collect intensity over an angular range simultaneously. They offer speed advantages up to one hundred times that of a point detector (scintillation and solid-state). Linear PSD detector may be held fixed over a 5 to 10 degree 2-theta range, or scanned like a point detector over a larger range. The speed of this detector is advantageous for high sample throughput, time resolved studies, weakly diffracting materials, and the detection of minor phases. | ||
| Solid State / Semiconductor | Solid-state or semiconductor detectors collect diffracted intensity from one angle at a time, and are scanned through the angular range of interest. These detectors provide the energy resolution of a diffracted-beam monochromator without the associated intensity loss, and offer a three- to fourfold speed advantage over a scintillation detector and monochromator. There are many types of solid-state detectors. Examples include germanium, Si (Li) (lithium drifted silicon), CCD (charge coupled device), PDA (photo diode array), PIPS (passivated implanted planar silicon), and SSB (silicon surface barrier). Semiconductor detectors typically require cryogenic cooling to improve the signal-to-noise ratio. | ||
| Scintillation | Scintillation detectors consist of a fluorescent crystal (e.g., NaI, plastic scintillators) bonded to the end of a photo-multiplier tube. Scintillation detectors collect diffracted intensity from one angle at a time and are scanned through the angular range of interest. They may be used with Kbeta filters or with diffracted-beam monochromators. | ||
| Other | Other detector types such as Geiger counters or gas flow proportional counters. | ||
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Configuration
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| Diffraction Method: | |||
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| Powder | Powder or polycrystalline samples are irradiated with a beam of X-rays and the resulting powder diffraction pattern is recorded with a detector such as photographic film, CCD, image plate, PSD, etc. The powder method is the most widely applied technique in the field of X-ray diffraction analysis for the identification of phases or compounds and the measurement of lattice spacing. There is a Powder Diffraction File with over a hundred thousand characteristic diffraction patterns ("fingerprints") for elements, alloys, minerals and organic compounds at http://www.icdd.com/. | ||
| Laue - Single Crystal | Diffraction patterns from a single crystal are produced using a beam of white X-ray radiation. The range of wavelengths in the white X-ray radiation assures that diffracting conditions will be met. | ||
| Rotating Crystal | In the rotating crystal method, a single crystal is rotated and irradiated with monochromatic X-ray beams. As the crystal rotates, a series of lattice planes are brought into diffracting conditions and the diffraction pattern is collected with film or detectors. The rotating crystal method is used in determining the structure of unknown materials (no matching fingerprints) and to provide an unequivocal determination of unit cell dimensions. | ||
| Other Method | Other unlisted variations of the basic methods (Lang, Borrman, rocking curves, diffractometer, etc.) can be applied for crystal quality/perfection, topographic, texture, or residual stress studies. | ||
| Search Logic: | All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. | ||
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| Sample/Detector Positioning System: | |||
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| Goniometer | Goniometers are rotary positioning tables and sample holders used to orient a sample to specific angles to produce a diffraction pattern and to reposition the sample to the desired crystallographic orientation. | ||
| Eulerian Cradle | Eulerian cradles are rotary positioning units where the axis of rotation is located outside the body of the unit. These cradles consist of an open, cylindrical design where the sample or a goniometer is mounted to the inner surface of the cradle. A combination of a cradle and goniometer can produce a 4-circle diffractometer. | ||
| Translation Stage | Translation stages are linear positioning stages that allow the translation of a sample, goniometer, cradle, or detector along an X, Y and/or Z axis. | ||
| Other | Other simple stages or sample holders for the powder method, or robotic positioners. | ||
| Search Logic: | All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. | ||
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| Diffracted Beam Optics: | |||
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| Monochromating Crystal | Monochromating crystals or monochromators use the diffraction conditions of a crystal to produce a monochromatic X-ray beam. Crystals with different lattice spacing and tilts (lattice planes) are used to provide the desired beam of the desired wavelength. Monochromators are used on the incident beam to produce the monochromatic beam required to produce a diffraction pattern in the sample, and to filter out undesirable white or Bremsstrahlung radiation from the diffracted beam. | ||
| Collimators and Slits | A series of slits, soller slits, divergence slits, etc., produce a collimated beam with less angular divergence. They may be used on the incident or diffracted beam. | ||
| K-Beta Absorption Filter | Absorption filters utilize the X-ray absorption edge characteristics of a material to filter out the K-beta peak and some white radiation from an incident beam to produce a more monochromatic beam of radiation. | ||
| Search Logic: | All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. | ||
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Performance Specifications
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| Angular Range | The 2-theta angular range is the range of diffracted beam (2-theta) angles that can be measured. | ||
| Search Logic: | User may specify either, both, or neither of the limits in a "From - To" range; when both are specified, matching products will cover entire range. Products returned as matches will meet all specified criteria. | ||
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| Angular Accuracy | Angular accuracy is the resolution in the diffracted angle that can be measured on a diffracted angle-vs.-intensity plot, or a diffraction pattern. | ||
| Search Logic: | User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. | ||
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| Peak Count Rate | Peak count rate is the maximum count rate in counts per second (cps) produced by the substrate and measured by the X-ray detector. | ||
| Search Logic: | User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. | ||
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| Maximum Specimen Diameter | The maximum specimen width or diameter that can be analyzed in the x-ray diffraction instrument. This feature is important in selecting an instrument for mapping or quality studies on silicon wafers. | ||
| Search Logic: | User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. | ||
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Features
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| Benchtop | Benchtop devices are larger and heavier instruments for dedicated use in a laboratory. | ||
| Hand-Held / Portable | Diffractometers are transportable for field applications such as residual stress analysis. | ||
| Texture / Preferred Orientation | Texture or preferred crystal orientation of individual grains (crystallites) in a polycrystalline sample is commonly measured through the determination and analysis of pole figure plots. | ||
| Measures Crystallite Size | Instruments are capable of measuring the particle size of a powder sample or the grain size of a polycrystalline material. | ||
| Single Crystal Orientation | Techniques that allow the determination of the orientation of the crystallographic planes in a single crystal sample. The method is important for the semiconductor industry, which uses single crystal silicon substrates (wafers) of known crystallographic orientation. Material properties such as hardness and etching rate change with orientation. | ||
| Residual Stress Measurement | Residual stress produces strain or a lattice deformation in a sample and a corresponding change in lattice spacing. The change in lattice spacing will cause a shift or broadening of the diffraction lines or spots. | ||
| High Resolution / Crystal Quality | Rocking curves, reflectometry, topography, reciprocal space mapping, micro diffraction or other methods are used in crystal quality assessments or other high resolution studies. X-ray topography or microscopy is used to examine defects within a crystal structure. These crystal defects or imperfections reflect more strongly and therefore produce dark regions on the X-ray topograph or reflection image. Rocking curves provide an indication of sub-grains and surface roughness in a crystal. Micro diffraction uses a small incident X-ray beam with a diameter less than 100 microns for investigation of small samples or a particular region of larger samples. Reflectometry uses the refractive index of thin film or semiconductor materials to provide density, surface roughness, composition variation, interfacial thickness, and total film thickness with depth-profiling capability through the film. | ||
| Search Logic: | All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. | ||
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