X’Pert Pro MRD Diffractometers

General description

X’Pert Pro MRD systems are mainly used to study small-angle scattering of hard X-rays. This method is one of the most developed and popular in practice methods of non-destructive testing of the internal structure of crystals and polycrystalline substances, multilayer structures, surface microroughness and other physical objects. The short wavelength, comparable to interatomic distances, determines the sensitivity of the method to the atomic structure of materials. Despite the low scattering ability of radiation atoms in this spectral range, X-ray interference in most cases leads to a resonant increase in the intensity of scattered (reflected) radiation, thereby providing researchers with reliable information on the structural and other properties of the objects under study. In addition, due to the low absorption and scattering of radiation in air, most experiments are carried out without the use of vacuum equipment, which significantly reduces the time of preparation and conduct of the experiment.

Currently, two devices (PANalytical and Philips X’Pert PRO MRD) are used at the IPM RAS for certification of MRD at the final stages and in scientific research. The devices allow studying crystalline materials and artificial multilayer systems by the X-ray diffraction method, including small-angle diffraction. The X-ray source is an X-ray tube (operating voltage and current up to 30 kV and 20 mA, respectively). Spectral and angular monochromatization of the probe beam is performed using a four-crystal asymmetric Ge (220) monochromator. The operating wavelength of Cu Kα1 radiation is λ = 0.154 nm. Slits are installed at the monochromator output, limiting the beam in the horizontal and vertical planes. The angular divergence of the radiation in the dispersion plane of the samples under study is 12 arc seconds. In the center is a table for fixing the sample, which is mounted on a goniometer with 6 degrees of freedom, allowing local study of both flat and curved samples over the entire surface. On the left is a gas proportional detector. In front of the detector is a holder with a Soller collimator, limiting the vertical divergence of the beam and an entrance slit.

Philips X’Pert PRO MRD allows obtaining curves of specular reflection and diffuse scattering of hard X-ray radiation and can be used for the following types of analysis:

1. Determination of parameters (period, roughness of interlayer boundaries, material densities) of multilayer periodic structures and films with d ~ 0.8-100 nm. Including the distribution of the period value over the mirror surface.

2. Characterization of the surface of ultra-smooth (up to several Å) samples, such as substrates for multilayer X-ray optics and microscopy: determination of the root-mean-square deviation, spectral density function, correlation length.

3. Determination of the phase composition (crystalline, amorphous structure) of thin films and bulk materials.

Technical specifications

Characteristic	Range	Accuracy
Horizontal beam divergence, °	< 0.0053
Vertical beam divergence, °	-
Horizontal divergence of the recorded beam, °	0.008-0.54*
Vertical divergence of the recorded beam, °	1.15**
Sample scanning angle Θ, °	-4.75° - +81.50°	лучше 0.001
Detector angular scanning 2Θ, °	-9.50° - +163.0°	лучше 0.001
Sample rotation Ф, °	360	0.01
Sample tilt Ψ, °	180 (±90)	0.01
Scan X, mm	100	0.01
Scan Y, mm	100	0.01
Z scan, mm	11	0.001
Maximum sample size, mm	100×100×24***
Maximum sample weight, kg	0.5

^* The minimum divergence of the beam recorded by the detector is determined by the beam size on the sample being studied (45 µm), the maximum is determined by the largest receiving slit of the detector (3 mm)

^** Determined by a vertical Soller collimator installed behind the detector slits

^*** Without removing the holder, the maximum sample thickness is 10 mm

External appearance of the X’Pert Pro MRD diffractometer

Internal structure of the X’Pert Pro MRD diffractometer

1 – Sample mounting stage,
2 – X-ray tube,
3 – Four-crystal monochromator,
4 – Monochromator outlet slits,
5 – Gas proportional detector,
6 – Holder with Soller collimator,
7 – Entrance slit.

Schematic diagram of the X’Pert Pro MRD diffractometer

Scheme of movements provided by the goniometer