Behaviour Of Beryllium Research Articles

Implications of the serpentine phase transition on the behaviour of beryllium and lithium–boron of subducted ultramafic rocks

The Totalp–Platta–Malenco ophiolites in the Eastern Central Alps offer a unique opportunity to study the behaviour of Li, Be and B in ultramafic rocks in response to serpentinization and to progressive Alpine metamorphism. These units represent the remnants of a former ocean-continent transition that was intensely serpentinized during exposure on the Jurassic seafloor of the Ligurian Tethys. From north to the south, three isograd reactions ( lizardite ⇒ antigorite + brucite;lizardite + talc ⇒ antigorite;lizardite + tremolite ⇒ antigorite + diopside ) have been used to quantify the evolution of the light element content of metamorphic minerals. We determined the Li, Be and B concentrations in major silicate minerals from the ultramafic bodies of Totalp, Platta and Malenco by secondary ion mass spectrometry. Mantle minerals have Be concentrations (e.g. <0.001–0.009 μg/g in olivine) similar to the metamorphic minerals that replace them (e.g. <0.001–0.016 μg/g in serpentine). The mantle signature of Be is thus neither erased during seafloor alteration nor by progressive metamorphism from prehnite-pumpellyite to epidote-amphibolite facies. In contrast, the Li and B inventories of metamorphic minerals are related to the lizardite-to-antigorite transition. Both elements display higher concentrations in the low-temperature serpentine polymorph lizardite (max. 156 μg/g Li, max. 318 μg/g B) than in antigorite (max. 0.11 μg/g Li, max. 12 μg/g B). Calculated average B/Li ratios for lizardite (∼1395) and antigorite (∼115) indicate that Li fractionates from B during the lizardite-to-antigorite transition during prograde metamorphism in ultramafic rocks. In subduction zones, this signature is likely to be recorded in the B-rich nature of forearc fluids. Relative to oceanic mantle the Be content of mantle clinopyroxene is much higher, but similar to Be values from mantle xenoliths and subduction-related peridotite massifs. These data support previous hypothesis that the mantle rocks from the Eastern Central Alps have a subcontinental origin. We conclude that Be behaves conservatively during subduction metamorphism of ultramafic rocks, at least at low-temperature, and thus retains the fingerprint of ancient subduction-related igneous events in mantle peridotites.

Study of the microstructure of neutron irradiated beryllium for the validation of the ANFIBE code

The behaviour of beryllium under fast neutron irradiation is a key issue of the helium cooled pebble bed tritium breeding blanket, due to the production of large quantities of helium and of a non-negligible amount of tritium. To optimise the design, a reliable prediction of swelling due to helium bubbles and of tritium inventory during normal and off-normal operation of a fusion power reactor is needed. The ANFIBE code (ANalysis of Fusion Irradiated BEryllium) is being developed to meet this need. The code has to be applied in a range of irradiation conditions where no experimental data are available, therefore a detailed gas kinetics model, and a specific and particularly careful validation strategy are needed. The validation procedure of the first version of the code was based on macroscopic data of swelling and tritium release. This approach is, however, incomplete, since a verification of the microscopic behaviour of the gas in the metal is necessary to obtain a reliable description of swelling. This paper discusses a general strategy for a thorough validation of the gas kinetics models in ANFIBE. The microstructure characterisation of weakly irradiated beryllium pebbles, with different visual examination techniques, is then presented as an example of the application of this strategy. In particular, the advantage of developing 3D techniques, such as X-ray microtomography, is demonstrated.

Partitioning of trace elements during the combustion of coal and biomass in a suspension-firing reactor

A novel, quartz ‘suspension-firing’ reactor is described for monitoring trace element release during solid fuel combustion under conditions relevant to fluidised bed combustors. The new design allows the examination of fuel particle combustion in the absence of bed solids. Experiments have been conducted using two coals, a sample of wood bark and one of straw. Ash from the reactor walls and base have been analysed separately from ash collected on a sintered disc in the path of exit gas. Trace element concentrations in these samples were analysed by Inductively Coupled Plasma (ICP)-mass spectrometry and ICP-atomic emission spectrometry (AES). The fractions of original trace elements retained by the ash have been reported; relative enrichment in the ‘sinter-ash’ was calculated by comparing with ‘bottom ash’. Mercury was almost completely volatilised from all fuels, as was selenium for all except wood-bark. Chromium, manganese and thallium were partially volatilised and nickel mostly retained in all samples. The behaviour of beryllium, lead, molybdenum, vanadium and zinc varied, depending on the fuel sample. Beryllium was released to a greater extent from coal/straw than the other fuels. Vanadium was partially volatilised from wood-bark and coal/straw, while the largest proportion of the zinc released was from the wood-bark. Lead and molybdenum were retained to a greater extent by ‘Colombian coal’ and wood-bark, respectively. Evidence of the enrichment of certain trace elements on the finer ‘sinter-ash’ particles has also been observed, e.g. for As, Cd, Pb and Tl during the combustion of the ‘Colombian-coal’.

Compatibility of refractory metals and beryllium with molten Pb [sbnd]17Li

The compatibility of V, Nb, Ta, Mo, W and Re with static eutectic mixture Pb 17Li was investigated experimentally. All these metals are very stable in the eutectic up to 600°C. Dissolution rates as well as solubilities are low. Below 600°C, a chemical reaction zone caused by initiation of an intergranular corrosion was observed. There was a strong isothermal mass transfer to the crucible wall. Diffusion coefficients for vanadium were calculated. They are in the expected range. The behaviour of beryllium is included in this paper for comparison. Diffusion coefficients were determined. In spite of low dissolution rates a strong intergranular corrosion causes destruction of this metal.

Effect of the nature of diluent on the extraction of beryllium by Aliquat 336 thiocyanate

The extraction behaviour of beryllium from HCl-KCNS by Aliquat 336, a quaternary ammonium halide, in various diluents is described. The dependence of extraction on thiocyanate concentration, pH of aqueous phase, metal and extractant concentrations, has been investigated. Extraction mechanism is suggested on the basis of results obtained.

Deformation Behaviour of Beryllium Under Compression Parallel to the Basal Plane

Deformation Behaviour of Beryllium Under Compression Parallel to the Basal Plane

The behaviour of beryllium μ4‐oxo‐μ‐carboxylates under electron impact

AbstractThe electron impact mass spectra of eight polynuclear beryllium complexes Be4O(RCO2)6 (RH, CH3, C2H5) and Be4O(RCO2)5OR′ (RCH3, R′H, CH3, C2H5, C3H7; RC2H5, R′C2H5) are reported. The major fragmentations involve the elimination of (RCO)2O (RCOOR′) or Be(RCO2)2 (Be(RCO2)OR′) from the ions [ML]+ and of {(RH)CO}, (R′H), H2O and BeO from the lighter ions. The fragmentation patterns are practically independent of the organic groups present and can be rationalized by stereochemical considerations.