X-ray Luminescence Spectroscopy Research Articles

Investigation of europium oxide (Eu2O3) doped in cobalt boro-silicate glasses from waste glass for photonics material application

The boro-silicate glasses have been doped with different concentration of Eu2O3 keeping constant CoO concentration (0.02 mol%) and synthesized in melt quench technique, these glasses are characterized through physical parameters, optical absorption, photo, and X-ray luminescence spectroscopy. The results showed that the optical characteristics of the samples are dependent on the Eu2O3 content rather than CoO content inside the glass. We observe tetrahedral dominance of Co2+ in the present glass system. The absorption spectra showed the three broad band of Co2+ ion at 4T1 g(F) → 2T1 g, 4A2 (4F) → 1T1 (4P), and 5T2 g → 5Eg respectively. Using optical absorption spectra, the crystal field parameter (10Dq), Racah parameter (B) were evaluated for all the concentration of Eu3+ doped glass. The phonon side band spectrum shows 1067.98 cm−1 for the present glass system. The integral scintillating efficiency have been studied and exhibited that the value show 8.78 % compared with commercial BGO scintillating crystal. Judd-Ofelt intensity parameters were investigated and used to compute the radiative properties of present glasses. These studies are useful for optimizing glass composition and could be useful for the optical display devices.

Optical properties of CsI:Tl crystals grown using different precursors purities

CsI doped with Tl (CsI:Tl) is a scintillator material used for radiation detector applications. CsI:Tl was crystalized by a modified homemade Bridgman-Stockbarger technique using different precursor purities. The purpose is to verify effects of precursor purity on optical properties of Cs:Tl crystals by UV-VIS and X-ray luminescence spectroscopy. A type and concentration of impurities in the precursor are directly related the optical properties of CsI:Tl crystals. The CsI:Tl crystals were grown in two levels of CsI and TlI reactant materials, i.e., having as a very high purity of 99.999%, showing a colorless crystal and a high purity of 99.9% showing an orange crystal. Absorption coefficient determined by transmittance and reflectance spectra was used to find an optical gap in the CsI:Tl crystals. For the colorless crystal, optical gaps of the Tl-related state and the CsI bandgap were observed at 3.82 eV and 5.14 eV, respectively. On the other hand, a merging of the Tl-related state and the CsI bandgap was observed for the orange crystal to form a virtual single bandgap at 3.51 eV. These results indicated the effects of precursor purity on optical gap of the CsI:Tl crystals. Also, X-ray luminescence spectra centred at 2.07 – 2.25 eV, which are corresponding to that of the absorption edge, showed a red shift of 160 meV for the orange CsI:Tl crystal.

15 lutetium compounds screened for Ce[formula omitted] activated scintillation

We report the scintillation luminosities, decay times, and emission wavelengths of eight new Ce3+ activated lutetium scintillators, two of which are also new compounds. Candidate compounds were (1) selected by empirical estimates of densities, bandgaps, and the potentials for Ce3+ activation; (2) synthesized as crystalline granules in arrays of automated furnaces; (3) verified by X-ray diffractometry; and (4) measured by X-ray luminescence spectroscopy and pulsed X-rays. By calibrating with Lu2SiO5:Ce crystals of similar grain size (average 0.5 mm) we estimate that the luminosities of the eight new scintillators range from 1000 to 27,000 photons/MeV and all show the characteristic Ce3+ doublet emission. The same undoped compounds have intrinsic scintillation with lower luminosities and different emission spectra. While most of these scintillators do not have properties that make them candidates for widespread use, their data will contribute to a deeper understanding of the factors that limit scintillation performance. In addition, we list seven lutetium compounds whose intrinsic scintillation was quenched by the incorporation of Ce3+.

Mechanism of the Effect of High-Voltage Nanosecond Pulses on the Structural, Chemical, and Technological Properties of Natural Dielectric Minerals

The mechanism behind the modification of the surface chemical structure and technological and physicochemical properties of Ca-bearing minerals (calcite, scheelite, and fluorite) under the effects of highvoltage nanosecond pulses is investigated by means of XPS, FTIR, X-ray luminescence spectroscopy, electrophoretic light scattering (ζ-potential), atomic-force microscopy (Kelvin probe force microscopy), microhardness measurements, and an approach based on the adsorption of acid–base indicators with different intrinsic pKα parameters. The acceptor properties of calcite and scheelite surfaces grow and the electron donor ability of fluorite increases as a result of pulsed electric field processing (ttreat ~ 30 s, Nimp ~ 3 × 103). The impact of energy pulses results in the formation of structural defects, surface softening (a 50–67% reduction in microhardness), and a directional change in mineral electric properties. Preliminary electropulse treatment generally enhances mineral flotation activity by 5–12%.

Solution combustion synthesis, photoluminescence and X-ray luminescence of Eu-doped nanoceria CeO2:Eu

Rare earth Eu3+-doped nanoceria with an average size of 60 nm were synthesized by urea–nitrate solution combustion reaction. The microstructure and morphology of the samples were characterized by X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM). The host is confirmed to be pure CeO2. However, there are two distinct oxygen surroundings due to the substitution of Ce4+ species with Eu3+ ions. The optical properties of CeO2:Eu were investigated by photoluminescence and X-ray luminescence spectroscopy. The samples can be excited with 360 nm (ultra-violet light, the charge transfer band of O–Ce) and 466 nm (blue light, the Eu3+ 7F0 → 5D2 transition) respectively, and exhibit typical red-light emission of Eu3+. At low Eu3+ concentrations, the sample can be effectively excited with 360 nm. With the increase of the Eu3+ concentration, the dominant excitation wavelength is changed to 466 nm, which is beneficial for use in solid state lighting because of the coincidence with the emission of GaN chips. Under the excitation of 466 nm, the quenching concentration of Eu3+ can be increased to 16 mol% due to the interface effects of the nanoscale materials. Furthermore, the X-ray luminescence of CeO2:Eu also shows strong red-light emission, manifesting that the material is a promising scintillator for radiation detection.

Degradation of GaAsP photocathodes under bombardment by ions of residual gases

Processes occurring in the near-surface region of semiconductor photocathodes based on an epitaxial multilayer GaAsP structure activated by a CsO monolayer have been investigated via secondary ion mass spectroscopy, X-ray luminescence spectroscopy, and electron microscopy. The main mechanisms of photoemitter degradation have been revealed. The main cause of degradation is low-energy heavy ion implantation into the near-surface region of the cathode, which changes the electron structure of the surface.

Growth dissymmetrization of rare earth element distribution and the Sm-Nd isotope system in fluorite crystals of the Nordvik deposit (Taymyr)

Mineralogists and physicist have long been interested in the nature and regularities of the zonal‐sectoral structure of mineral monocrystals, but in many cases they have not found adequate explanation. In some works it was shown that dissymmetrization of physical features observed for such objects to a significant degree was connected with fractionation of trace elements and atomic groups by symmetrical nonequivalent facets of the growing crystal. For example, D. Rakovan et al. [1] has revealed a strongly expressed sectoral zonality in the distribution of trace rare earth elements (REE) in crystals of natural apatite with the help of synchrotron X-ray fluorescence microanalysis (SXRFMA). Analogous but weaker and ambiguously revealed effects have also been established for fluorite from several American deposits [2]. In [3] we used the method of high-resolution X-ray luminescence spectroscopy and discovered a special type of fluorite crystals of cuboctahedral habit (KOF‐1 type) characterized by distinctly revealed separation of “light” (LLn) and “heavy” (HLn) trace lanthanoid ions in different pyramids of growth of one growth zone of crystal. Among such objects, cuboctahedral fluorite crystals from the Nordvik deposit (Taymyr) are investigated in detail in this work. The deposit of optical fluorite Nordvik is located in the Uryung‐Tumus peninsula of the Khatanga Gulf and is connected with one of the salt dome and oil-bearing structures situated within the Enisey‐Khatanga basin. Fluorite mineralization is mainly connected with the cap rock carbonate blocks. The peculiarities of the fluorite genesis and geological structure of the Nordvik deposit were described earlier [4‐6]. Two transparent and colorless fluorite crystals of rare (for the Nordvik deposit) cuboctahedral habit were used in our investigation. Crystals of about 4 cm in diameter were sampled from the fluorite‐calcite veinlet localized in the lowest part of the dolomitic cap rock of the Nordvik deposit western flank. According to the data of thermobarogeochemical investigation (E.V. Tolmachev), both crystals were formed from hydrothermal solutions under the temperature 340‐370 ° C. 1