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Paineira Beamline

PAINEIRA (Powder X-ray Diffraction) will be a beamline optimized for the X-ray diffraction of polycrystalline materials in Debye-Scherrer geometry (capillary geometry or transmission mode). This technique allows the characterization of the three-dimensional ordering of atoms or molecules in materials, i. e. the crystalline structure.

The X-ray source will be an undulator and therefore the experimental station will have a photon flux of the order 10,000 times higher than the XPD beamline in the old UVX. This will allow for rapid data collections. Thus, it will allow the characterization of intermediate crystalline phases, as well as the structural evolution of samples under in situ and operando conditions. The measurement geometry is ideal for samples in powder form, but polycrystalline pellets and films can also be analyzed using suitable sample holders currently under development.

PAINEIRA will deliver photon energies from 5 to 30 keV (2.48 – 0.41Å) and will use an upgraded Newport Heavy-Duty 3-circle diffractometer, previously operated at the UVX, XRD1 beamline (Fig. 1 -1)).

The PAINEIRA beamline will operate in two measurements setups, a high-resolution mode or a fast detection mode. The high-resolution mode, using a multi-analyzer crystal system (Fig. 2), will provide detection of X-ray diffraction peaks of the order of 0.008° full width at half maximum (FWHM). As this detector requires step-wise counting, X-ray diffraction patterns are estimated at 1 h per data collection. In rapid detection mode, the diffracted beam will be collected using an arc-shaped 2D detector system, covering 100° in 2θ per acquisition. This system will provide a resolution of 0.05° (FWHM) at 2 θ and the diffraction pattern will take the order of seconds to be acquired.

Figure 1. Design of the experimental station of the PAINEIRA beamline: 1) 3-circle diffractometer, (Heavy-Duty from Newport); 2) High-resolution detector; 3) Fast arc-shaped 2D detector covering 100° in 2θ; 4) Sample magazine with capacity for 120 capillaries; 5) Robotic arm for automated sample changing; 6) Supports for cryo jet and air blower to be used in cooling and heating of samples; 7) Robotic arm that will pick up and hold the cryo jet or hot air blower near to the capillary during the acquisition. 8) Gas flow control module and experimental control module for in-situ and operando experiments.

The experimental station will contain robotically automated sample exchange with the option of heating or cooling the sample in the capillary with a hot air blower (25 – 800 °C) and cryojet (-196 – 120 °C) (Fig. 1). Using these automated features, called high-throughput operation mode, the user can opt for high-resolution detection mode where the beamline software will be able to automatically determine the optimal measurement parameters for the experiment, depending on the scientific case. In the case of experiments with medium angular resolution requirements (rapid detection and resolution of 0.05° (FWHM)), users will be able to collect hundreds of diffractograms within minutes or hundreds of samples within hours. In addition, the user will have a reaction cell in capillary geometry, with systems to control gas flow and pressure of gases and liquids, vapor flow and gas analyzers (mass spectrometer and micro-GC) to perform chemical reaction experiments during data collections (see Table 3). A sample holder system is under development that will allow the application of electric fields to materials in the form of bulk and films. Some of the primary scientific areas to benefit from the experiments will be materials science applications (drug design, catalysis, devices for energy storage and capture, such as batteries and supercapacitors, multiferroic ceramics) and Environmental Sciences (geoscience).

CONTACT & STAFF

Facility E-mail: paineira@lnls.br

Coordination: Cristiane B. Rodella
Tel.: +55 19 3512 1040
E-mail: cristiane.rodella@lnls.br

Click here  for more information on this Facility team.

EXPERIMENTAL TECHNIQUES

HIGH-RESOLUTION X-RAY DIFFRACTION

High-resolution data collections will be obtained using a system of 8 Si (111) analyzer crystals, aligned in front of point scintillator detectors as shown in Figure 2. The system acts to remove background as well as other artefacts that contribute to peak broadening and florescence. The diffracted X-ray beam passes through the analyzer crystals at a very narrow selection angle before reaching the detector. This angle, which is defined by the Darwin width of Si at the energy of the experiment, will allow only diffracted beams meeting the Bragg condition to be detected. For example, at 15 keV, with a Si (111) crystal analyzer, the Darwin width is approximately 3.55 arcsec. This setting will produce very narrow diffraction peaks and remove background noise, resulting in high resolution and optimized signal-to-noise ratio in the XRD data. It is estimated that diffraction peaks with width FWHM of the order of 0.008° 2θ are readily resolved. However, this detection mode requires a longer acquisition time compared to the rapid acquisition detector albeit with a reduction in resolution. 1h collection times are expected for a 5-100° high-resolution pattern at 15 keV. This results in high-resolution acquisition times more than 10x faster than that at the old XPD beamline at UVX.

Figure 2. The MAC system from FMB-Oxford for high-resolution experiments.

MEDIUM RESOLUTION (RAPID-ACQUISITION) X-RAY DIFFRACTION

The rapid acquisition angular detector is a project under internal development by the LNLS detector group in partnership with Pi-Tecnologia Brasil. The proposal is to build a detection system based on Medipix3RX ASIC sensors for rapid detection to optimize beamline measurement times for scientific cases requiring medium angular resolution couples with time resolved studies in the second time range. This setup takes into account scientific cases with the demand for temporal resolution and/or sample sensitivity to X-rays (sample damage by X-ray beams).

Called Arcpix, this detector has 10 modules, with 2 elements of each, installed in an arc on the delta circle of the heavy-duty diffractometer. Each Si element (Medipix3RX ASIC) has a 256 x 1550 pixel chip with 55 μm x 55 μm each pixel placed at 89 cm from the sample, resulting in an angular resolution of 0.05° (FWHM). Read rate will be up to 1000 frames per second. The setup will result in both wide angular coverage and measurement agility with 100° 2θ range collected in a few seconds. As it is a 2D detector (256 pixels x 30,060 pixels), an azimuthal integration will be done to transform the data into a 1D pattern. The detector will be set up to rock between two positions to cover any blind spots between the individual detector units. Thus, two individual offset measurements will be summed to produce a single continuous diffractogram with software taking care of overlap and integration corrections necessary for the final data (Intensity vs. 2θ plot) to be quickly visualized by the user.

SAMPLE ENVIRONMENTS

PAINEIRA will provide sample holders, reaction cells, and analytical equipment for measurements under ambient conditions and will also allow sample heating, and cryogenic cooling. Added to this, reactions may be simulated with the addition of reactant gasses and pressure experiments to simulate operando conditions. The beamline research group will also continually be working on new instrumentation developments for in-situ and operando experiments and for the scientific community of users. The table below shows systems already developed and available infrastructure once the beamline is operational.

Sample holders, reaction cells and accessories for experiments at PAINEIRA.

LAYOUT & OPTICAL ELEMENTS

Element Type Position [m] Description
Source Insertion device U18 – Kyma
White beam slit Slit 27.9 Determination of beam divergence
Beam diagnostics Diagnosis 28.2 Visualization and diagnosis of the white beam
Double crystal monochromator Bruker Monochromator 30.0 Monochromatization
Beam diagnostics 32.0 Monochrome beam visualization and diagnosis
Monochrome beam slit 43.4 Monochrome beam slit
Beam diagnostics 43.4 Initial intensity counter (I0)
X-ray attenuator 44.8 Beam attenuator
Robotic arm GP25 – Motoman 45.2 Sample room changer
In situ design control module Development in house 45.5 Gas flow control and design control
Diffractometer Heavy-Duty, 3-circles 46.0 Sample alignment with incident beam and diffracted beam detectors
Detection system MAC – Oxford FMB 46.0 Set of 8 independent analyzer crystals with ~2° 2θ separation of scintillating detectors (FMB-Oxford)
Detection system ARCPIX (in-house development) 46.0 Fast arc-shaped detector with 100° angular coverage
Robotic arm GP8 – Motoman 46.5 Sample changer
Sample Magazine Development in house 47.0 Sample storage carousel where gp8 robot will transfer sample
X-ray beam visualization X-ray and photodiode eyes 47.5 Transmitted beam viewer

PARAMETERS

Parameter Value Condition
Energy range 5 – 20 keV
14 – 30 keV
Si(111)
Si(311)
Flux at sample [ph/s] ~1013 15 keV
Energy resolution (ΔE/E) ~10-4 15 keV
Angular resolution (MAC) 0.008° FWHM @ 15 keV
Angular range in 2θ (MAC) 3 – 145°
Angular resolution (ARCPIX) 0.05° (all energies)
Angular range at 2θ (ARCPIX) 3° – 100°
Beam size [mm x mm] 1.1 (v) x 1.7 (h) FWHM @ 15 keV
Beam divergence [μrad] 25 (v) x 37 (h) FWHM @ 15 keV