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Borate Phosphors for Neutron Radiography
Published in S. K. Omanwar, R. P. Sonekar, N. S. Bajaj, Borate Phosphors, 2022
All the borate phosphors considered have better gamma discrimination compared to NIP based on BaFBr:Eu2+. However, NIP based on lithium borate can be expected to have ultimate properties as it is low Z (Zeff = 7.4). Scintillation properties of lithium metaborate Li2BO2 and tetraborate Li2B4O7 (LBO) were already known [95]. These materials were first used as boron-containing additives in polystyrene luminescent composition for thermal neutron detection [96]. The scintillation compositions, however, were heterogeneous and showed a low transparency for the intrinsic emission in the UV region because those compounds were low soluble both in the initial monomer and in polystyrene. The transparency region of LBO crystals is within the range from 160 to 3,200 nm. These crystals exhibit photoluminescence (PL) with a maximum at 330–340 nm when being excited by vacuum UV at 133 nm. The radioluminescence (RL) spectrum of LBO crystals is identical to the PL one and is characterized by three decay components with τ1 < 2ns, τ2~ 5 ns and τ3 = 50~100 µs; it is just the process with τ3 that defines the main part of the light yield. The light yield for undoped lithium tetraborate single crystals is about 100 photons/MeV. The doping with copper (0.08 mol%) results in appearance of a maximum about 370 nm and a longer decay component (perhaps in the millisecond range). The light yield of doped LBO crystals increases by a factor of about 5.
Iron Particles in Freshwater
Published in Jacques Buffle, Herman P. van Leeuwen, Environmental Particles, 2019
William Davison, Richard De Vitre
The distribution of heavy metals between various phases of suspended solids in rivers has been investigated using schemes based on chemical reactivity (see Reference 15 for a review of these procedures). Tessier et al.16 sequentially treated the samples as follows: (i) 1 M MgCl2 at pH 7 (exchangeable metal); (ii) 1 M acetate, pH 5 (metals bound to carbonates); (iii) 0.04 M NH2OH at 96°C (metals bound to Fe-Mn oxides); (iv) 30% H2O2, pH 2, 85°C (metals bound to organic matter); (v) fusion with lithium metaborate (residual metals). For two rivers draining mixed catchments, with quartz, plagioclase, and chlorite dominating the suspended solids, the iron was found to be mainly associated with fraction (v), 61 and 73%, and fraction (iii), 32 and 22%. The remainder was in the organic (4.8 and 3.8%) and carbonate (2.1 and 1.3%) fractions. These results indicated that about one third of the iron was present as reactive, presumably amorphous oxyhydroxides and two thirds incorporated in the crystal lattices of clay minerals and silicates or present as refractory iron oxide.
Primary growth zoning and oscillatory zoning of Iceland spar from the Razlom deposit (Siberia, Russia)
Published in Vladimir Litvinenko, Innovation-Based Development of the Mineral Resources Sector: Challenges and Prospects, 2018
M.N. Logunova, J. Götze, M.A. Ivanov, G. Heide
To evaluate the appropriate method for the investigation of the micro-zonation, preliminary analyses concerning the kind and concentration of impurity elements in the samples were performed using emission spectrometry with inductively coupled plasma (ICP-MS) at the Karpinskii All-Russia Research Institute of Geology in St. Petersburg using their standard laboratory methods. The ICP-MS measurements using an Elan 6100 (PerkinElmer, USA) equipment were done with powder samples (weight for analysis 50 mg) prepared from selected sectors. The powdered samples were digested in a mixture of nitric, hydrofluoric and hydrochloric acid, as well as by preliminary alloying of the sample powder with a flux (lithium metaborate). The samples were analyzed for most common elements (except Fe, due to the possible introduction of this component during cutting of the samples), as well as rare earth elements (REE). Calibration was carried out according to standard samples from PerkinElmer company.
Provenance of the Pakawau Group and Farewell Formation (Late Cretaceous – Paleocene), Taranaki Basin, northwest Nelson, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2020
Sarah L. Smithies, Kari N. Bassett, Greg H. Browne, Alexander R. L. Nichols
Spectrachem Ltd. analysed the samples for major and trace elements by X-ray fluorescence spectrometry (XRF). Two granite basement samples from the Separation Point Suite at Knuckle Hill were also analysed (Table 2). Spectrachem Ltd. prepared the crushed samples by drying to 110°C, which was used as the reporting basis. Loss on ignition (LOI) was calculated by ignition at 1000°C. For major element analysis, a lithium metaborate/tetraborate fused glass bead was prepared. For trace element analysis, a pressed powder briquette was made using 10% analytical-grade wax binder. A SRS3000 Siemens/Bruker X-ray fluorescence spectrometer was used for both major and trace element analysis. The Spectrachem laboratory has ISO17025 Certification (CRL Energy Ltd 2017; International Organization for Standardization 2017). The geochemical data are available in supplementary data and online through the Petlab database (Table 2) (Strong et al. 2016).