Search results for "Synchro"
showing 10 items of 886 documents
High pressure in-situ X-ray diffraction study on Zn-doped magnetite nanoparticles
2018
We have performed high pressure synchrotron X-ray powder diffraction experiments on two different samples of Zn-doped magnetite nanoparticles (formula Fe(3-x)ZnxO4; x = 0.2, 0.5). The structural behavior of then a noparticles was studied up to 13.5 GPa for x = 0.2, and up to 17.4 GPa for x = 0.5. We have found that both systems remain in the cubic spinel structure as expected for this range of applied pressures. The analysis of the unit cell volume vs. pressure results in bulk modulus values lower than in both end-members, magnetite (Fe3O4) and zinc ferrite (ZnFe2O4), suggesting that chemical disorder may favor compressibility, which is expected to improve the increase of the Neel temperatu…
Synchrotron Radiation and Chemistry: Studies of Materials for Renewable Energy Sources
2014
We present an overview of selected applications of synchrotron radiation methods to topical chemical research. The analysis is limited to the studies on materials for renewable energy sources, focussing on topics peculiar to chemical research, such as reactivity and synthesis routes; in particular, the paper takes into account subjects having some relevance for the production and storage of energy based on hydrogen. Hydrogen production and storage are taken into account in the sections concerning: (i) Dye-sensitized solar cells, (ii) Metal-organic frameworks and (iii) Hydrides for hydrogen storage; production of energy by fuel cell devices is treated in (iv) Oxide ion and proton conductors …
Rapid nanocrystallization of soft-magnetic amorphous alloys using microwave induction heating
2009
The crystallization of Fe73Nb3Cu1Si16B7 alloy during microwave heating was investigated in situ using synchrotron radiation powder diffraction. The phase transformation comprises a primary nanocrystallization stage and a final microcrystallization step. We provide evidence for a strong enhancement of the transformation kinetics. Microwave heating occurs as a result of both ohmic and magnetic losses induced by eddy currents, which defines a volumetric microwave induction heating process. Nanocrystallization is completed within 5 s, while full crystallization is achieved in less than 10 s.
Investigations of the formation mechanism of nanostructured NbAl3 via MASHS reaction
2002
Abstract The nanostructured NbAl3 intermetallic compound was synthesized using the mechanically-activated self-propagating high-temperature synthesis (MASHS) technique. This process results from the combination of two steps: a short duration ball-milling of a pure elemental Nb+3Al powder mixture followed by a self-propagating high-temperature synthesis (SHS) reaction induced by the Nb+3Al reaction exothermicity. Synchrotron time-resolved XRD coupled with a 2D infrared camera were used to investigate the structural and thermal evolutions during the SHS reaction, and to study in situ the mechanism of NbAl3 formation. The influence of the incoming heat flux and the mechanical activation effect…
Excitation of different chromium centres by synchrotron radiation in MgO:Cr single crystals
2015
The excitation spectra for the emissions of chromium-containing centres have been measured at 10 K using synchrotron radiation of 4–32 eV in MgO single crystals with different content of Cr$^{3+}$ (5–850 ppm) and Ca$^{2+}$ impurity ions. Both virgin crystals and the samples preliminarily irradiated with x-rays at 295 K have been studied. The role of complex chromium centres containing two Cr$^{3+}$ and a cation vacancy (sometimes nearby a Ca$^{2+}$ ion) on the luminescence processes and the transformation/creation of structural defects has been analysed. Such anharmonic complex centres could serve as the seeds for the creation of 3D defects that facilitate the cracking and brittle destructi…
Luminescence and vacuum ultraviolet excitation spectroscopy of cerium doped Gd3Ga3Al2O12 single crystalline scintillators under synchrotron radiation…
2020
Authors gratefully acknowledge the financial support from the Latvian Science Council grant LZP-2018/2-0358 . The research leading to this result has been supported by the project CALIPSO plus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON2020 . The work of A.P.K. was supported by the Ministry of Science and Higher Education of the Russian Federation , state contracts No. 11.6181.2017/ITR .
Micrometer-resolution reconstruction and analysis of whole mouse brain vasculature by synchrotron-based phase-contrast tomographic microscopy
2021
AbstractNervous tissue metabolism is mainly supported by the dense thread of blood vessels which mainly provides fast supplies of oxygen and glucose. Recently, the supplying role of the brain vascular system has been examined in major neurological conditions such as the Alzheimer’s and Parkinson’s diseases. However, to date, fast and reliable methods for the fine level microstructural extraction of whole brain vascular systems are still unavailable. We present a methodological framework suitable for reconstruction of the whole mouse brain cerebral microvasculature by X-ray tomography with the unprecedented pixel size of 0.65 μm. Our measurements suggest that the resolving power of the techn…
Luminescence of nano- and macrosized LaPO4:Ce,Tb excited by synchrotron radiation
2011
Abstract Comparing the luminescence properties of nanosized and macroscopic LaPO4:Ce,Tb powders are performed in wide spectral range using synchrotron radiation. In the present study, LaPO4:Ce,Tb nanopowder was produced by means of a microwave-induced synthesis in ionic liquids, whereas the bulk sample represents a commercial lamp phosphor. Emission and excitation of both, Ce3+ and Tb3+ luminescence, is observed to be different when comparing bulk and nanosized LaPO4:Ce,Tb. In particular, it was shown that the fine structure of the Ce3+ as well as the Tb3+ related emission is poorly resolved for the nanomaterial. It is suggested that the nanoparticles surface plays a key role regarding the …
Remote voltage synchronization for wireless Partial Discharge diagnostics
2016
The main objective of this paper is the assessment of the exact phase angle displacement of each Partial Discharge, PD, pulse with respect to the voltage reference waveform. Such problem also referred to as ‘synchronization’ is relevant when the cable is not accessible and the PD measure is carried out in wireless mode. It is well known, that the angle phase shift, due to the propagation phenomenon on the transmission line, can be calculated knowing the line type and length and typical operating conditions of the transmission line. The setup comprises a customized electronic device, the “Phase check”, a server to collect remote measurements and a Look up table to provide corrections to the …
Electronic excitations in ZnWO4 and ZnxNi1−x WO4 (x = 0.1 − 0.9) using VUV synchrotron radiation
2011
The photoluminescence spectra and luminescence excitation spectra of pure microcrystalline and nano-sized ZnWO4 as well as the Zn x Ni1−x WO4 solid solutions were studied using vacuum ultraviolet (VUV) synchrotron radiation. The samples were also characterized by x-ray powder diffraction. We found that: (i) the shape of the photoluminescence band at 2.5 eV, being due to radiative electron transitions within the [WO6]6− anions, becomes modulated by the optical absorption of Ni2+ ions in the Zn x Ni1−x WO4 solid solutions; and (ii) no significant change in the excitation spectra of Zn0.9Ni0.1WO4 is observed compared to pure ZnWO4. At the same time, a shift of the excitonic bands to smaller en…