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1.
Materials (Basel) ; 16(19)2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37834632

RESUMO

All-in-one radiation shielding is an emerging concept in developing new-generation radiation protection materials since various forms of ionizing radiation, such as neutrons and gamma rays, can occur simultaneously. In this study, we examine the ability of transition metal borides to attenuate both photon and particle radiation. Specifically, fourteen different transition metal borides (including inner transition metal borides) are selected for examination based on their thermodynamic stabilities, molecular weights, and neutron capture cross-sections of the elements they contain. Radiation shielding characteristics of the transition metal borides are computationally investigated using Phy-X/PSD, EpiXS and NGCal software. The gamma-ray shielding capabilities of the transition metal borides are evaluated in terms of the mass attenuation coefficient (µm), the linear attenuation coefficient (µ), the effective atomic number (Zeff), the half-value layer (HVL), the tenth-value layer (TVL), and the mean free path (MFP). The mass and linear attenuation factors are identified for thermal and fast neutrons at energies of 0.025 eV and 4 MeV, respectively. Moreover, the fast neutron removal cross-sections (∑R) of the transition metal borides are calculated to assess their neutron shielding abilities. The results revealed that borides of transition metals with a high atomic number, such as Re, W, and Ta, possess outstanding gamma shielding performance. At 4 MeV photon energy, the half-value layers of ReB2 and WB2 compounds were found as 1.38 cm and 1.43 cm, respectively. Most notably, these HVL values are lower than the HVL value of toxic Pb (1.45 cm at 4 MeV), which is one of the conventional radiation shielding materials. On the other hand, SmB6 and DyB6 demonstrated exceptional neutron attenuation for thermal and fast neutrons due to the high neutron capture cross-sections of Sm, Dy, and B. The outcomes of this study reveal that transition metal borides can be suitable candidates for shielding against mixed neutron and gamma radiation.

2.
Materials (Basel) ; 16(2)2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36676598

RESUMO

In this study, boron carbide powders consisting mainly of nano/micro fibers or polyhedral-equiaxed particles were synthesized via the sol-gel technique, and the influence of particle morphology on electrochemical performance of boron carbide electrodes was investigated. Thermal decomposition duration of the precursors played a determinant role in the final morphology of the synthesized boron carbide powders. The morphology of boron carbide powders successfully tuned from polyhedral-equiaxed (with ~3 µm average particle size) to nano/micro fibers by adjusting the thermal decomposition duration of precursors. The length and thickness of fibers were in the range of 30 to 200 µm and sub-micron to 5 µm, respectively. The electrochemical performance analysis of boron carbide powders has shown that the particle morphology has a considerable impact on the boron carbide electrodes electrochemical performance. It was found that the synergetic effects of polyhedral-equiaxed and nano/micro fiber morphologies exhibited the best electrochemical performance in supercapacitor devices, resulting in the power and energy density of 34.9 W/kg and 0.016 Wh/kg, respectively.

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