Search results for "Spectral line"
showing 10 items of 1453 documents
Raman characterization of Pb2Na1−xLaxNb5−xFexO15 and Pb0.5(5−x)LaxNb5−xFexO15 (0≤x≤1) solid solutions
2011
Abstract The ferroelectric compounds Pb 2 Na 1− x La x Nb 5− x Fe x O 15 and Pb 0.5(5− x ) La x Nb 5− x Fe x O 15 (0≤ x ≤1) with the tungsten bronze type structure have been investigated using Raman spectroscopy. The evolution of the spectra as a function of composition at room temperature is reported. In the frequency range 200–1000 cm −1 three main A 1 phonons around 240 ( υ 1 ), 630 ( υ 2 ) and 816 ( υ 3 ) cm −1 were observed. The broadening of the Raman lines for high values of x originates from a significant structural disorder. This is in good agreement with the relaxor character of these compositions. The lowest-frequency part of the spectra, below 180 cm −1 , reveals a structural ch…
Crystalline phase detection in glass ceramics by EPR spectroscopy
2018
The advances of EPR spectroscopy for the detection of activators as well as determining their local structure in the crystalline phase of glass ceramics is considered. The feasibility of d-element (Mn2+, Cu2+) and f-element (Gd3+, Eu2+) ion probes for the investigation of glass ceramics is discussed. In the case of Mn2+, the information is obtained from the EPR spectrum superhyperfine structure, for Gd3+ and Eu2+ probes – from the EPR spectrum fine structure, whereas for Cu2+ ions the changes in the EPR spectrum shape could be useful. The examples of EPR spectra of the above-mentioned probes in oxyfluoride glass ceramics are illustrated. ----/ / /---- This is the preprint version of the fol…
Influence of surface topography on depth profiles obtained by Rutherford backscattering spectrometry
2000
A method for determining correct depth profiles from samples with rough surfaces is presented. The method combines Rutherford backscattering spectrometry with atomic force microscopy. The topographical information obtained by atomic force microscopy is used to calculate the effect of the surface roughness on the backscattering spectrum. As an example, annealed Au/ZnSe heterostructures are studied. Gold grains were observed on the surfaces of the annealed samples. The annealing also caused diffusion of gold into the ZnSe. Backscattering spectra of the samples were measured with a 2 MeV 4He+ ion beam. A scanning nuclear microprobe was used to verify the results by measuring backscattering fro…
Annealing behaviour of aluminium-implanted InP
2000
The annealing behaviour of aluminium has been studied in single-crystal InP implanted with 40 and 120 keV 27Al+ ions. The implantation doses were 1 x 1015 and 1 x 1016 cm-2. The aluminium concentration profiles were determined by two techniques, Secondary ion mass spectrometry (SIMS) and the nuclear resonance broadening technique (NRB) which was used for checking purposes. The usability of the SIMS technique for profiling Al rich layers was studied. Significant inconsistencies were observed in the SIMS profiles with the high dose implanted samples. The 120 keV, 1 x 1016 cm-2 implanted samples were subject to annealing in argon atmosphere in the temperature range 380–600°C. Redistribution an…
Accumulation of radiation defects and modification of micromechanical properties under MgO crystal irradiation with swift 132Xe ions
2020
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. A.A. also acknowledges support via the project GF AP05134257 of Ministry of Education and Science of the Republic of Kazakhstan .
Stopping cross-section measurements of 4He in TiN1.1O0.27
2000
Abstract The stopping cross-section for 4He projectiles in TiNx compounds has been measured using the backscattering method. A multi-compound marker layer deposited between the test film and the substrate was used to obtain the stopping cross-section at several energies with one energy of the incident beam. Two RBS spectra at definite tilt angles of the sample are taken for each beam energy. The assistance of computer codes to synthesize RBS spectra is very useful to obtain the pertinent information from the displacements of the peaks of the marker layers. Stopping cross-section values are obtained with an estimated uncertainty of about 6%.
Two-neutron correlations at small relative momenta in ^40Ar + ^197Au collisions at 60 MeV/nucleon
2000
Two-neutron correlation functions are measured in the 40Ar + 197Au reaction at 60 MeV/nucleon to study the space-time characteristics of neutron emitting sources. The source temperatures and velocities are deduced by fitting the single-neutron energy spectra with a three-source model. A comparison of the correlation data with the predictions of the model of moving sources and with the dynamical Landau-Vlasov model suggests the relevance of a multisource description. Particular care has been paid to the influence of the relative source abundance on the shape of the correlation function.
Radiation emission at channeling of electrons in a strained layer undulator crystal
2013
Abstract Experiments have been performed at the Mainz Microtron MAMI to explore the radiation emission spectra from a crystalline undulator at electron beam energies of 270 and 855 MeV. The epitaxially grown graded composition strained layer Si 1 - x Ge x undulator had 4-period with a period length λ u = 9.9 μ m . Spectra taken at the beam energy of 270 MeV at channeling in the undulating (110) planes exhibit a broad excess yield around the theoretically expected photon energies of 0.069 MeV, as compared with a flat silicon reference crystal. Model calculations on the basis of synchrotron-like radiation emission from finite single arc elements, taking into account also coherence effects, su…
Positron trapping defects in free-volume investigation of Ge–Ga–S–CsCl glasses
2016
Abstract Evolution of free-volume positron trapping defects caused by crystallization process in (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 15 chalcogenide-chalcohalide glasses was studied by positron annihilation lifetime technique. It is established that CsCl additives in Ge–Ga–S glassy matrix transform defect-related component spectra, indicating that the agglomeration of free-volume voids occurs in initial and crystallized (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 10 glasses. Void fragmentation in (80GeS 2 –20Ga 2 S 3 ) 85 (СsCl) 15 glass can be associated with loosing of their inner structure. Full crystallization in each of these glasses corresponds to the formation of defe…
Tetrahedral versus octahedral Mn site coordination in wurtzite and rocksalt Zn1−xMnxO investigated by means of XAS experiments under high pressure
2007
Abstract We present the results of x-ray absorption measurements carried out in Zn 1− x Mn x O thin films under high pressure. The Mn environment remains essentially the same for nominal Mn concentrations given by x = 0.05 , 0.1, 0.15 and 0.25. Both the XANES (X-ray Absorption Near Edge Structure) and EXAFS (Extended X-ray Absorption Fine Structure) indicate that Mn occupies the Zn site, being surrounded by four oxygen atoms at 2.02±0.01 A. The substitutional hypothesis is reinforced by comparing the differences between the ambient (wurtzite) and high pressure (rocksalt) spectra, which correspond to tetrahedral and octahedral Mn environments.