Functional Bi2O3/Gd2O3 Silica-Coated Structures for Improvement of Early Age and Radiation Shielding Performance of Cement Pastes.

This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances.

Mechanical properties and durability of cobalt free steel alloy as a developed radioactive waste capsule.

In this work, Cobalt-free alloys are prepared as a capsule in which radioactive waste is placed for disposal, and this is a preventive measure to rid the environment of radioactive waste and bury it deep in the earth in a capsule. So, the buildup factor was measured for 1-5-10-40 MFP. The mechanical properties (hardness and toughness) of the processed samples were studied. The hardness was calculated by the Vickers hardness test additionally; the tolerance process was carried out using concentrated chloride acid for 30 days and NaCl 3.5% for 30 days for the studied samples. In this work the resulted developed alloys are resistant to stainless steel 316 L and therefore the alloys are a suitable material in the nuclear field as a container for burying and disposing of waste.

Structure, Mössbauer, electrical, and γ-ray attenuation-properties of magnesium zinc ferrite synthesized co-precipitation method.

For technical and radioprotection causes, it has become essential to find new trends of smart materials which used as protection from ionizing radiation. To overcome the undesirable properties in lead aprons and provide the proper or better shielding properties against ionizing radiation, the tendency is now going to use ferrite as a shielding material. The co-precipitation method was utilized to prevent any foreign phases in the investigated MZN nano-ferrite. X-ray diffraction (XRD) and Fourier transmission infrared spectroscopy (FTIR) methods were used to analyze the manufactured sample. As proven by XRD and FTIR, the studied materials have their unique spinel phase with cubic structure Fd3m space group. The DC resistivity of Mg-Zn ferrite was carried out in the temperature range (77-295 K), and its dependence on temperature indicates that there are different charge transport mechanisms. The Mössbauer spectra analysis confirmed that the ferrimagnetic to superparamagnetic phase transition behaviour depends on Zn concentration. The incorporation of Zn to MZF enhanced the nano-ferrite density, whereas the addition of different Zn-oxides reduced the density for nano-ferrite samples. This variation in density changed the radiation shielding results. The sample containing high Zn (MZF-0.5) gives us better results in radiation shielding properties at low gamma, so this sample is superior in shielding results for charged particles at low energy. Finally, the possibility to use MZN nano-ferrite with various content in different ionizing radiation shielding fields can be concluded.

Enhanced optical and structural features of Ni2+/La3+ hybrid borate glasses.

Glasses with the formula [80B2O3-4.0La2O3-(16-x) PbO-xNiO, (x ranged from 0.0 to 4.0 mol%)], were produced by the standard quenching method. XRD, SEM and EDAX analysis established the success of the obtained samples preparation. Density measurements and FT-IR analysis confirmed the structural modifications emerging by the entry of Ni2+ ions as a network modifier, where the structural unit's ratio of BO3 (BO4) was affirmed to increase (decrease) with a gradual rise of NBO's number. The semiconducting behavior of the current glassy samples was verified by the role of the structural modifications in decreasing the gap energy and increasing both Urbach and mineralization criterion. Ligand field analysis applied to the absorption spectra exhibited the covalent nature of the Ni2+ bonds. The behavior of electronic polarizability supported the gradual increases of the linear and non-linear refractive index of the samples. These properties qualify the present glasses as an optically active material for the devices operated in the visible-NIR regions.

New approach to removal of hazardous Bypass Cement Dust (BCD) from the environment: 20Na2O-20BaCl2-(60-x)B2O3-(x)BCD glass system and Optical, mechanical, structural and nuclear radiation shielding competences.

In the present work, aiming to collaborate in the removal of Bypass Cement Dust (BCD) from the environment, we studied a system consisting of three glasses prepared from analytical reagent grade chemicals with the following composition: 20Na2O-20BaCl2-(60-x)B2O3-xBCD, where (x = 0, 10, and 20 %). BCD is an important contributor of many respiratory human health issues. In this work we investigate their optical, physical and gamma-ray shielding properties. The experimental results of mass attenuation coefficients are contrasted with the FLUKA Monte Carlo code and the XCOM database at 0.081, 0.356, 0.662, 1.173, and 1.332 MeV photon energies. Additionally, the mechanical, structural, and optical properties of these glasses were measured. A rising peak with an increase of BCD concentration in the region from 450 cm-1 to 480 cm-1 was observed. The results show that shielding properties such as the mass attenuation coefficient (µm), the effective atomic number (Zeff), and the effective electron density (Nel) increase as BCD fraction increases. The half value layer (HVL), the tenth value layer (TVL), and the mean free path (MFP) decrease as the BCD content increases. It is noticed that 20Na2O-20BaCl2-(60-x)B2O3-xBCD, where (x = 0, 10, and 20 %), has the highest optical conductivity value at x = 20%. It was found that the gradual addition of BCD content increases the hardness of the studied glasses.

Thermoluminescence characteristics of lithium borosilicate glass doped with Sm2 O3.

Lithium borosilicate glass composite (SiO2 -Li2 CO3 -H3 BO3 ) doped with various concentrations of Sm2 O3 (0-0.7 mole %) was prepared using the melt quenching method. The investigated thermoluminescence (TL) characteristics of the prepared system revealed that the highest TL response was obtained for this glass composite at 0.05 mol% Sm2 O3 . In this study, the 0.05 mol% Sm2 O3 -doped lithium borosilicate glass composite was subjected to detailed dosimetric investigation in terms of its annealing condition, dose-response, and minimum detectable dose. The reproducibility of the response, thermal characteristics, and optical fading were also studied. The obtained results showed that the prepared glass composite had a linear dose-response over the wide gamma dose range 2Gy to 2 kGy, as well as reasonable thermal fading and excellent reproducibility. These attributes render the composite under investigation promising for utilization in radiation detection.