# VISÃO GERAL

VOLTAR

The XPD beamline is an experimental station dedicated to Powder X-ray Diffraction analysis and operates from 6 to 12 keV. However, the energy is set at 8keV (for maximum flux) and it is only changed to perform anomalous scattering experiments or to eliminate the effect of fluorescence for samples containing specific elements, such as Fe. The beamline focuses on the structural studies of crystalline and nanocrystalline materials and it is able to perform both high resolution and faster in-situ experiments under non-ambient conditions.

XPD’s source is a 1.67T bending magnet, with a Huber 4+2 circle diffractomete, working in Bragg-Brentano geometry (theta-2theta) providing high quality powder diffraction data. Powder X-ray diffraction techniques largely benefit from the high-brilliance of synchrotron light sources in terms of photon flux, angular resolution, higher resolution, energy tunability as well as in situ studies in combination with fast detectors.

XPD is a beamline for studying the structure of all forms of polycrystalline materials, especially in a powder form. It offers the acquisition of powder patterns in high resolution mode, allowing the investigation of strain, lattice defects, and micro-structure of materials at ambient and cryogenic temperatures. In addition, powder diffraction using a synchrotron radiation X-rays source and fast detectors has become an essential technique for studying the change in crystalline or nanosized materials as a function of time under a variety of experimental conditions such as, temperatures ans gas. XPD allows kinetic experiments using a furnace installed onto the diffractometer, which allows gases to interact with the samples to simulate various reaction conditions or environments. A Mythen 1k linear detector can be used for fast data acquisition during in situ experiments. The beamline energy can be changed to perform anomalous scattering experiments, in which the contrast between scattering factors of different elements can be conveniently tuned. Energy tunability also eliminates the effects of fluorescence.

# CONTATO & EQUIPE

Telefone da Linha de Luz: +55 19 3512 1131
E-mail da Linha de Luz: xpd@lnls.br

Coordenação: Cristiane Barbieri Rodella
Telefone: +55 19 3512 1040
E-mail: cristiane.rodella@lnls.br

Clique aqui  para mais informações sobre a equipe da Linha de Luz.

# TÉCNICAS EXPERIMENTAIS

As técnicas e configurações experimentais a seguir estão disponíveis nesta linha de luz. Para saber mais sobre as limitações e requerimentos das técnicas, contate o coordenador da linha de luz antes de submeter sua proposta.

###### AMBIENT MEASUREMENTS

Ambient measurements are conducted on samples which require the high resolution capability of the beamline. Here samples are measured under ambient temperatures and are exposed to the atmosphere during measurements. The setup gives accurate peak position and shape and reduces peak overlap of highly crystalline materials while reducing background signal. This set-up is normally required for quantitative analysis of samples, i. e. Structure determination of performing Rietveld Refinement to determine crystalline parameters, such as cell parameter and volume, crystal size, investigation of strain, lattice defects and micro-structure of materials. It is carried out at ambient conditions (room temperature) in Bragg-Bretano geometry or at cryogenic temperature with a cryostat. It is important to note that the cryostats work without sample spinning and the theta angle is fixed during the measurement. High resolution requires an analyzer crystal, a Ge (111) crystal, installed before the point detector (Cyberstar scintillation detector), which provides a step-size resolution of 0.02° in $\rm 2\theta$. This analysis mode results in low photons flux and thus a lower intensity of the diffracted beam and consequently, longer data acquisition times (4-10 hours for each sample).

###### IN-SITU MEASUREMENTS

Anton Paar XRK 900 (only available with Cyberstar detector)

Right: Canario Furnace

These measurements involve the use of a furnace with the additional capability of gas flow. With this setup various types of reactions can be simulated. The temperature range is dependent on the furnace used (please see types of furnaces available at the beamline). Various gas environments are allowed to simulate chemical reactions. Some restrictions are in place for safety as well as preventing damage to the furnaces. Thus, no corrosive gases are allowed. Further, restrictions apply to the use of hydrogen (5% max) and oxygen (20% max). We strongly urge you to contact the beamline staff prior to sending a beamtime proposal to certify that your experiment fits into our safety regulations. A mild vacuum may be applied to the furnace as well as humidity if required. A mass spectrometer is also available to analyze the chemical composition at the outlet of the furnace. The appropriate furnace will be selected by the beamline staff depending on the needs of the user.

The in-situ setup works for both fast measurements (lower resolution) using the Mythen 1K detector as well as the High resolution setup using the Cyberstar point detector. Please note the large time differences in collecting data between these two detectors. For further information about more complex setups, please contact the beamline staff.

###### CRYOSTAT

Legenda – Cryostat from Advanced research systems

For low temperature measurements, a cryostat from Advanced research systems is available. The lowest temperature achievable is around 2 K using He or 10 K using N. Samples measured using the cryostat are also considered as high resolution and thus long measurement times are required (3-6 hours per sample).

###### SAMPLE PREPARATION

Legenda – Sample holders from left to right: Furnace, cryostat, High-resolution

Depending on the type of experimental setup required samples may be prepared as either a powder or pellet. Powder samples are preferred however. Samples need to be ground down to the finest possible size to avoid sample related effects affecting the data. This applies to all data collections.

###### BEAMLINE ENERGY

XPD is normally fixed at 8 keV ($\rm \lambda$=1.5498Å) which corresponds to the highest photon flux and is equivalent to Cu Kα wavelength used in conventional X-ray sources. However, the energy may be changed if anomalous diffraction experiment are required or if the sample is composed of Fe and/or Co. The energy is then set to 7 keV to avoid fluorescence. It is also possible to work at higher energies if it is important to increase the penetration depth of the X-rays into the sample, in the case of samples composed of high Z materials.

# LAYOUT & ELEMENTOS ÓTICOS

ElementoTipoPosição[m]Descrição
SRCBending Magnet0.0Bending Magnet D10 exit B (15°), 1.67 T,
FEFront-end--
S1White Beam Slits6.2LNLS Slits (Cu and Ta)
M1Cylindrical Vertical Collimating Mirror7.3Rh coated ULE, R = 1.7 to 21.7 km, $\theta$ = 4.5 mrad
DCMDouble Crystal Monochromator8.6Water cooled Si (111)
S2Monochromatic Beam Slits20.0LNLS Slits (Cu and Ta)
ESExperimental Station21.94+2 circles Huber diffractometer

# PARÂMETROS

ParâmetroValorCondição
Critical Energy [keV]2.08-
Energy range [keV][Å]4.5-15 (2.76-0.83)Si (111)
Energy resolution [$\Delta$E/E]$2.5 \times 10^{-4}$Si (111)
Beam size at sample [$\rm mm^{2}$, FWHM]3 x 2at 8 keV
Beam divergence at sample [$\rm mrad^{2}$, FWHM]1 x 0.1at 8 keV
Flux density at sample [ph/s/$\rm mm^{2}$]$2.5 \times 10^{10}$at 8 keV

# INSTRUMENTAÇÃO

InstrumentoTipoModeloEspecificaçõesFabricante
DetectorLinearMythen 1k$50\mu \rm m$ pixel, 1280 pixel, 2kHz frame rateDectris
DetectorPoint DetectorCyberstar X1000$\phi$ = 30 mm, Tl-doped NaI (NaI(Tl)), $10^6\, \rm counts.s^{-1}$FMB Oxford
DetectorCCD CameraX-ray eyeA-ray sensitive CCDPhotonic Science
FurnaceIn-situ High Temperature Diffraction chamberAraraMax Temp.: 1000°C, Temp Rate: 10K/s, window port 210°LNLS in-house development
FurnaceIn-situ High Temperature Diffraction chamberCanarioMax Temp.: 1000°C, Temp Rate: 10K/s, window port 210°LNLS in-house development
FurnaceIn-situ High Temperature Diffraction chamberXRK900Max Temp.: 900°C, Temp Rate: 20K/sAnton Paar
Diffractometer4+2 circles5020$2\theta$ max=150°; 2$\chi$ max=90°Huber
Eurellian Cradle2 circles513360º $l\Phi$; 2$\chi$ max=150º, min=-45ºHuber
Sample CellsHumidity ChamberTucanoMax Temp.: 200°C, Temp Rate: 5K/s, Max RH = 80%, window port 210ºLNLS in-house development
CryostatsHe Closed Cycle Diffraction CryostatDE-202Closed Cycle Cryo-cooler, Temperature range: <10 K – 350K, Window Ports: 5 - 90° ApartARS Cryo
Analyzer CrystalMonochromatic CrystalGe(111)$2 \theta$ step: 0.0025ºLNLS in-house development
Analyzer CrystalMonochromatic CrystalSi(111)$2 \theta$ step: 0.0025ºLNLS in-house development
Analyzer CrystalMonochromatic CrystalHOPG(002)$2 \theta$ step: 0.05ºLNLS in-house development
Gas detectorMass SpectrometerQMA 100-Pfeiffer Vacuum
Gas detectorMass SpectrometerQMA 200-Pfeiffer Vacuum

# CONTROLE E AQUISIÇÃO DE DADOS

The beamline is controlled using EPICS (Experimental Physics and Industrial Control System) that is running on a PXI from National Instruments. All data acquisition and diffractometer movements are done using fourc mode on SPEC (software for instrumentation control and data acquisition in X-ray diffraction experiments from Certified Science Software).  For some graphical interfaces and beamline devices can be controlled using CSS (Control System Studio).

# REQUISIÇÃO DE TEMPO DE FEIXE

Chamados de submissão de propostas são abertos usualmente duas vezes ao ano, um para cada semestre. Todas as propostas de pesquisa acadêmica precisam ser submetidas eletronicamente através do portal SAU Online. Saiba mais sobre o processo de submissão de propostas aqui.

XPD beamline offers varied instrumentation setups to allow structural studies of materials. It is important when submitting a proposal to specify the required equipment and setup needed to carry out your experiments. Please see the information below to help you specify the beamline setup and accessories. However, it is important to contact the beamline staff before sending a proposal, especially if you are a new user or/and want to carry out a new experiment.

Beamtime: Working under ambient conditions, one XRD pattern will take from 4 to 10 hours in high resolution mode. This depends on the angular step and 2theta range of the experiment. It is important to take into account that NIST standards are measured before the begining of the experiment to determine wavelength corrections and the instrumental contribution to the peak-profile for structure solution or Rietveld refinement. The standard analysis will take the same time as a sample or more, on average 6-8h to LaB6 and 4-6h to Si. In the case of cryogenic experiments, you need to add 1h to heat the cryostat to room temperature and replace your sample. In the case of the in situ measurement with furnace and Mythen detection, the kinetics experiments will determine the experimental time (temperature range, heating rate, isothermal treatments, and number of XRD patterns acquired). However, it is important to consider that the furnace takes 40 min to cool down to room temperature. However, the Mythen detector is significantly faster with patterns attainable in 30 seconds

# COMO CITAR ESTA LINHA DE LUZ

Usuários devem declarar a utilização das instalações do LNLS em qualquer artigo, tese ou outro material publicado que utilize dados obtidos na realização de sua proposta.

This research used resources of the Brazilian Synchrotron Light Laboratory (LNLS), an open national facility operated by the Brazilian Centre for Research in Energy and Materials (CNPEM) for the Brazilian Ministry for Science, Technology, Innovations and Communications (MCTIC). The _ _ _ beamline staff is acknowledged for the assistance during the experiments.

Ou:

Esta pesquisa utilizou recursos do Laboratório Nacional de Luz Síncrotron (LNLS), uma instalação nacional aberta do Ministério da Ciência, Tecnologia, Inovações e Comunicações (MCTIC) operada pelo Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Agradecemos a equipe da Linha de Luz _ _ _ pela assistência durante os experimentos.

# PUBLICAÇÕES

Abaixo está disponível a lista de artigos científicos produzidos com dados obtidos nas instalações desta Linha de Luz e publicados em periódicos indexados pela base de dados Web of Science.

Atenção Usuários: Dada a importância dos resultados científicos anteriores para a processo geral de avaliação das propostas, recomenda-se que os Usuários verifiquem e atualizem suas publicações tanto no portal SAU Online quanto na As atualizações da base de dados da biblioteca devem ser feitas enviando a informação bibliográfica completa para a Biblioteca (biblioteca@cnpem.br). As publicações são incluídas após checagem pela equipe da biblioteca e pela coordenação das linhas de luz.

MAIS PUBLICAÇÕES

XPD

Nunes, W. G. ; Silva, L. M. da ; Vicentini, R. ; Freitas, B. G. A. ; Costa, L. H. ; Pascon, A. M. ; Zanin, H. G.. Nickel oxide nanoparticles supported onto oriented multi-walled carbon nanotube as electrodes for electrochemical capacitors, Electrochimica Acta, v. 298, p, 468-483, 2019. DOI: 10.1016/j.electacta.2018.12.102

XPD

Rade, L. L.; Lemos, C. O. T. ; Barrozo, M. A. de S.; Ribas, R. M. ; Monteiro, R. de S. ; Hori, C. E.. Optimization of esterification reaction over niobium phosphate in a packed bed tubular reactor, Renewable Energy, v. 131, p. 348-355, 2019. DOI: 10.1016/j.renene.2018.07.041

XPD

Rodrigues, M. V.; Okolie, C. ; Sievers, C. ; Martins, L.. Organosilane-Assisted Synthesis of Hierarchical MCM-22 Zeolites for Condensation of Glycerol into Bulky Products, Crystal Growth & Design, v.19, n. 1, p. 231-241, 2019. DOI: 10.1021/acs.cgd.8b01310

XPD

Romero, M.; Faccio, R.; Pardo, H.; Montenegro, B. ; Richard, D. ; Martínez, J. ; Navarro, A. M. M.; Mombrú, A. W.. Local structure and magnetic properties of Mn3+-O-Fe3+ superexchange interaction in an oxygen-vacant perovskite: Experimental and theoretical study, Journal of Magnetism and Magnetic Materials, v. 469, p. 224-230, 2019. DOI: 10.1016/j.jmmm.2018.08.070

XPD

Figueredo, G. P.; Medeiros, R. L. B. A.; Macedo, H. P.; Oliveira, A. S.; Braga, R. M.; Mercury, J. M. R.; Melo, M. A. F. de; Melo, D. M. A.. A comparative study of dry reforming of methane over nickel catalysts supported on perovskite-type LaAlO3 and commercial alpha-Al2O3, International Journal of Hydrogen Energy, v. 43, n. 24, p. 11022-11037, 2018. DOI: 10.1016/j.ijhydene.2018.04.224

DXAS   XPD

Teixeira, C. de O. P. ; Montani, S. da S.; Palacio, L. A.; Zotin, F. M. Z.. The effect of preparation methods on the thermal and chemical reducibility of Cu in Cu-Al oxides, Dalton Transactions, v. 47, n. 32, p. 10989-11001, 2018. DOI: 10.1039/c8dt01150h

MAIS PUBLICAÇÕES