Effect of Irradiation with Low-Energy He2+ Ions on Degradation of Structural, Strength and Heat-Conducting Properties of BeO Ceramics

The paper is devoted to the study of radiation-induced damage kinetics in beryllium oxide ceramics under irradiation with low-energy helium ions with fluences of 1015–1018 ion/cm2. It was revealed that at irradiation fluences above 1017 ion/cm2, a decrease in radiation-induced damage formation and accumulation rate is observed, which indicates the saturation effect. At the same time, the main mechanisms of structural changes caused by irradiation at these fluences are amorphization processes and dislocation density increase, while at fluences of 1015–1016 ion/cm2, the main mechanisms of structural changes are due to the reorientation of crystallites and a change in texture, with a small contribution of crystal lattice distorting factors. It was discovered that the radiation-induced damage accumulation as well as an implanted helium concentration increase leads to the surface layer destruction, which is expressed in the ceramic surface hardness and wear resistance deterioration. It was determined that with irradiation fluences of 1015–1016 ion/cm2, the decrease in thermal conductivity is minimal and is within the measurement error, while an increase in the irradiation fluence above 1017 ion/cm2 leads to an increase in heat losses by more than 10%.

A model of FeN-decorated BeO layer particle for CO gas adsorption

Carbon monoxide (CO) is known as a deathful gas produced by burning of hydrocarbons in a lack of enough oxygen, in which breathing CO leads to serious issues on human life health quality. Therefore, adsorption of CO gas is an essential task for diagnosis or removal of this dreadful gas in environment. To do this, a HEME-like model of iron-nitrogen-doped beryllium oxide (FeNBeO) monolayer was investigated for adsorbing CO gas by performing density functional theory (DFT) calculations. Two models were obtained for this process, in which relaxation of CO with C-head or O-head towards Fe region of monolayer. The results indicated that the formation of FeNBeO-CO model could be achieved more favorable than the formation of FeNBeO-OC model. The obtained optimized geometers and energies all approved this achievement for favorability of FeNBeO-CO model formation. Moreover, molecular orbital based electronic features indicated variations of such features for the models upon adsorption of CO substance, in which the models could be detectable in a sensor function for the existence of CO gas in the environment. As a consequence, the investigated FeNBeO monolayer could be proposed useful for adsorption of CO gas at least for the CO deathful gas diagnosis purposes.

Beryllium oxide nanoparticles: synthesis, characterization, and thermoluminescence evaluation for gamma radiation detection

In this study, beryllium oxide nanoparticles (BeO NPs) were synthesized by polymer-gel method with schlenk line. The products were then assessed using FESEM, TGA/DSC, XRD and BET analyses. The quality of two nanooxides, that were calcined at 700 and 800 °C, was studied and compared with bulk BeO particles. The results showed that nanoparticles calcined at 800 °C were more uniform and had ellipsoidal morphology with a particle size of ∼35 nm. Investigation thermoluminescence (TL) characteristics of BeO NPs showed that with the decreasing exposed dose/increasing the BeO particle size, TL peaks were observed at higher temperatures. The intensities of glow curves increase linearly with the increasing absorbed dose in the range of 0.001 mGy–1000 Gy. Various other studies including response fading, minimum temperature and minimum time for annealing, and response changes in repeatability cycles of dosimeter also approved the ability of the prepared BeO NPs for use in gamma radiation dosimetry.

Study of change in beryllium oxide strength properties as a result of irradiation with heavy ions

The paper presents data on changes in strength properties, including data on microhardness, crack resistance, bending strength and wear of BeO ceramics as a result of irradiation with heavy accelerated ions. The following types of ions were selected as heavy ions: O2+ (28 MeV), Ar8+ (70 MeV), Kr15+ (147 MeV), Xe22+ (230 MeV). Radiation doses were 1013 -1015 ion/cm2 , which make it possible to assess the effect of both single defects arising from radiation, and cluster overlapping defective areas occurring at large radiation doses. During the studies carried out, it was found that an increase in the ion energy and, consequently, in the damaging ability and depth of the damaged area, leads to a sharp decrease in the strength mechanical characteristics of ceramics, which is due to an increase in defective areas in the material of the near-surface damaged layer. However, an increase in irradiation dose for all types of exposure results in an almost equilibrium decrease in strength characteristics and the same trend of change in strength characteristics. The obtained dependencies indicate that the proposed mechanisms responsible for changing the strength properties can, under certain assumptions, be extrapolated to various types of exposure to heavy ions in the energy range (25-250 MeV).

Modeling of heat transfer in a fuel pellet based on uranium dioxide and ceramics (beryllium oxide)

The results of heat transfer mathematical model calculations in the “UO2-BeO” pellet are presented. The fuel pellet consists of uranium dioxide (UO2) and beryllium oxide (BeO) ceramics. Modeling of heat transfer was carried out by a system of generalized heat conduction equations with variable thermophysical properties. The calculated data of the temperature field in the fuel pellet were obtained using the COMSOL Multiphysics software code. The results of temperature calculations were compared with the data of other authors. The agreement of the calculated data shows the mathematical model and the COMSOL Multiphysics code algorithms correctness. Various arrangements of beryllium oxide ceramics BeO in a fuel pellet are considered. The arrangement of the BeO ceramics in the centre of the fuel pellet showed a noticeable decrease in temperature in the energy release zone. Calculations have shown that the composite fuel “UO2-BeO” is the most effective for regulating the thermal regime of fuel elements.