D8 X-ray diffractometer by Bruker AXS
The X-ray diffractometer D8 by Bruker AXS operates in the theta-theta mode, i.e. the sample introduced horizontally into the sample holder is not moved during the measurement. The instrument with a modular design is equipped with two detectors: Sol-X, an energy-dispersive detector, and LynxEye, a super speed detector.
The typical penetration depth of the X-ray beam in the Bragg-Brentano measurement geometry utilized here is 1-40 μm, depending on the composition of the sample.
On the secondary side, the scattered radiation from the sample is filtered out by a Ni-filter, except for the K alpha1 and K alpha2 line.
Glass platelets with a recess are used as powder-preparation mount. Small sample amounts are measured by a one-crystal sample mount. Compact samples should have a planar surface and not exceed dimensions of 5×5×2 cm.
X’Pert – MPD (Multi Purpose Diffraction System) – diffractometer by PANalytical
The MPD diffractometer operates in the theta-theta mode. The surface to be measured is always in a horizontal position while the tube and detector are moved. A proportional detector in combination with a parallel-beam collimator and a fast detector (X’Celerator) are attached on two detector arms.
When the slit optics are used, the X-ray beam is filtered using a beta-filter (Ni) that can be used on the primary or (and) secondary side.
In addition to the slit optics, an X-ray mirror can also be used upstream of the sample in the primary beam.
The use of the X-ray mirror in the primary beam brings about equatorial parallelization of the X-ray beam and an approximate monochromatization to K alpha radiation with high intensity. The divergence of the beam is approximately 0.04°. The insensitivity of the reflexes to height adjustment and roughness of the sample, brought about by the parallelization of the beam, allows a reliable analysis of the samples with curved and uneven surfaces. There is no peak displacement or reduction in the intensity in the case of a height misalignment in the range of ±250 μm.
The high-temperature chamber allows in situ examinations of the phase composition in powders, compact samples and thin layers between room temperature and 1400°C in air, and up to 2000°C in optionally either a protective-gas atmosphere or in a vacuum.
It is also possible to measure liquid and very heavy samples (up to 1 kg) which cannot be mounted on other instruments. Depending on the measurement configuration, the samples can have dimensions up to 10×10 cm. The available sample rotator (spinner) affords the possibility of largely eliminating texture effects in the x-y plane.
X’Pert – MRD (High-resolution Materials Research Diffractometer) – diffractometer by PANalytical
The high-resolution diffractometer (minimum step size 0.0001°, reproducibility ≤ 0.0002°) is equipped with an open Euler’s balance. An open Euler’s balance allows a phi-rotation of 360° and a psi-tilt in the region of 180° (±90°).
The instrument operates in a theta – 2theta mode. The sample is attached to the sample mount in a vertical position.
The line focus of the ceramic X-ray tube is used in conjunction with fully automatic and programmable optics or a parallel-plate collimator in conjunction with a planar-graphite monochromator; the point focus is used in conjunction with the X-ray lens and the parallel-plate collimator. A scintillation counter and a fast detector (X’Celerator) are available.
In the reflectivity mode, an attenuator is automatically inserted into the beam path at a preselected intensity (controlled by software) in order to realize an intensity range of up to eight orders of magnitude. The measured intensities are automatically corrected dependent on the attenuation factor. In the case of curved substrates, use is made of a beam-cutting stop, which is positioned in the vicinity of the sample surface and counteracts line broadening. Reflectometry measurements of amorphous and crystalline samples make it possible to determine the density and surface quality of compact samples and density, thickness, surface and intermediate-layer roughness of layers and successions of layers.
The use of an X-ray lens (polycapillary optics) in the primary beam brings about a parallelization of the divergent X-ray beam in an equatorial and axial direction. The lack of sensitivity of the reflexes on tilt (psi) and rotation (phi) of the sample achieved by this allows a reliable texture and stress analysis. Since there are no defocusing effects, determining the position of the reflex is reliable over the entire range of the tilt of the sample, which is very advantageous, particularly in stress analysis. It is also reliably possible to examine samples with a rough and angled surface.
The lens can be used to illuminate a precisely defined point on the sample with dimensions between 1×1 and at most 10×10 mm. The divergence of the Cu K alpha1, 2 radiation is 0.3°.
It is possible to examine samples with a diameter of 100 mm × 100 mm, a sample height of 24 mm and a maximum mass of 0.5 kg.