Xabier Mikel Turrillas Maisterra

Xabier Mikel Turrillas Maisterra

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Thickness estimation of TiO2-based nanotubes using X-ray diffraction techniques
2020 - FARIA, MARCELA E.M.; LEITE, MARINA M.; ICHIKAWA, RODRIGO U.; VICHI, FLAVIO M.; TURRILLAS, X.; MARTINEZ, L.G.
TiO2-based nanotubes are a very promising material with many applications in solar cells, biomedical devices, gas sensors, hydrogen generation, supercapacitors, and lithium batteries, among others. Nanotube thickness is a very important property since it is related to electronic and surface mechanics. In this sense, transmission electron microscopy (TEM) can be used. However, it can be difficult to acquire a good TEM image because the transversal section of the nanotubes needs to be visible. In this work, TiO2-based nanotubes obtained via hydrothermal synthesis were studied using X-ray line profile analysis. Scherrer and Single-Line methods provided consistent results for the thickness of the nanotubes (≃ 5 nm) when compared with TEM. Additionally, Single-Line method was also applied to estimate the microstrain. The advantage of using XRD is given by the fact that it is a quick and statistically significant analysis when compared with TEM. The results show that XRD can be used as a rapid and reliable alternative for the thickness estimation of nanotubes.
Estimativa da espessura de nanotubos através de dados de difração de raios X
2018 - FARIA, MARCELA E.M.; LEITE, MARINA M.; ICHIKAWA, RODRIGO U.; VICHI, FLAVIO M.; MARTINEZ, LUIS G.; TURRILLAS, XAVIER
The use of X-ray diffraction for phase identification of press hardened steels
2015 - COUTO, C.P.; COSTA, P.D.O.L.; MARTINEZ, L.G.; TURRILLAS, X.; ROSSI, J.L.
The numbers of hot stamped components have been steadily increasing in the automotive industry. Press hardened steels are generally used in hot stamping process since at the end of the process, the steel may achieve a tensile strength about 1500 MPa. The hot stamping process consists to heat the steel blank at total austenitization temperature and to transfer the blank into the press tooling for shaping and fast cooling to fully martensitic transformation. The transfer of the blank from the furnace to the press might promote at some extent, steel oxidation. The application of metallic coatings avoids this hindrance. The Al-Si has been the most applied coating on steel. In parallel, alternative coatings such as Zn-Ni have been developed. It is known that the heating causes chemical elements diffusion, which results in intermetallic formation between the elements presents in the coating and in the substrate. This study had the objective of characterizing hot stamped and coated 25MnB5 steel samples with Al-Si and Zn-Ni, with X rays diffraction (XRD) technique. Some literature suggested phases such as Zn-Fe, Zn-Ni-Fe or Al-Fe-Si were not seen on XRD results. Nonetheless, X-ray diffraction detected the presence of ZnO and α-Fe for Zn-Ni coated steel plate and Al5Fe2, AlFe3 and α-Fe for the Al-Si coated steel plate.
In situ hydration of sulphoaluminate cement mixtures monitored by synchrotron X-ray diffraction
2016 - ROSSETTO, C.M.; ICHIKAWA, R.U.; MARTINEZ, L.G.; CAREZZATO, G.L.; CARVALHO, A.M.; TURRILLAS, X.
The hydration of calcium sulphoaluminate cement mixtures was studied in situ by synchrotron X-ray diffraction at the XRD1 beamline of the Laboratório Nacional de Luz Síncrotron (LNLS – Campinas). The specimens were analyzed in borosilicate glass capillary tubes of 0.7 mm and imbued with deionized water. As the hydration reaction is very fast, the data collection was started after two minutes of mixing with water. The X-ray wavelength chosen to get an adequate flux for these short time acquisitions was 1.033258 Å, determined with a corundum standard. Diffraction patterns were collected every 35 seconds at temperatures ranging from 40°C to 55°C with accuracy better than 0.1°C attained with a hot air blower. The diffracted signal was collected with an array of 24 Mythen detectors. The diffraction patterns accumulated had appropriate statistics to determine the kinetics of the reaction either by quantitative Rietveld analysis or by fitting isolated diffraction peaks to Gaussian curves as a function of time. The most important phases involved in the hydration are Klein´s salt, also known as Ye’elimite, Ca4(AlO2)6SO4, and gypsum, CaSO4.2H2O to yield Ettringite, Ca6Al2(SO4)3(OH)12·26H2O, phase responsible for the mechanical properties. These studies show the potential of XRD1 beamline to investigate at controlled temperatures in situ fast reactions involving crystalline phases with time resolutions inferior to one minute, which is ideal for the hydration of cementitious mixtures.
Study of the microstructure in remelted zircaloy by synchrotron diffraction line profile analysis
2014 - ICHIKAWA, RODRIGO U.; MARTINEZ, LUIS G.; PEREIRA, LUIZ A.T.; IMAKUMA, KENGO; TURRILLAS, XABIER
Synchrotron diffraction characterization of alternative powder diffraction standards
2014 - MARTINEZ, L.G.; ICHIKAWA, R.U.; IMAKUMA, K.; ORLANDO, M.T.D.; TURRILLAS, X.
Size-strain x-ray line profile analysis and crystallite size distribution of nanostructured ZnO
2013 - ICHIKAWA, R.U.; MARTINEZ, L.G.; IMAKUMA, K.; TURRILLAS, X.; GUSATTI, M.; RIELLA, H.G.
Size-strain analysis of nanostructured Mn-Zn ferrites using x-ray line profile methods
2015 - ICHIKAWA, R.U.; PARRA, J.P.R.L.L.; MARTINS, M.L.; YOSHITO, W.K.; SAEKI, M.J.; TURRILLAS, X.; MARTINEZ, L.G.
Study of a highly crystalline Y2O3 sample by Rietveld and Pair Distribution Function Analysis
2015 - MARTINEZ, L.G.; ICHIKAWA, R.U.; TURRILLAS, X.
Portland cement paste behaviour under gamma radiation field in geological repository
2015 - FERREIRA, E.G.A.; VICENTE, R.; TURRILLAS, X.; VOKAICHIYA, F.; FRANCO, M.; MARTINEZ, L.G.; MARUMO, J.T.