RESUMO
The significance of radiation shielding is on the rise due to the expanding areas exposed to radiation emissions. Consequently, there is a critical need to develop metal alloys and composites that exhibit excellent capabilities in absorbing neutron and gamma rays for effective radiation shielding. Low-density Ti-based alloys with controlled structural properties can be used for radiation protection purposes. The present research investigates boron-doped Ti-based alloy, Ti50Cu30Zr15B5, which is synthesized by arc melting technique, and its structural, mechanical properties, neutron, and gamma-ray transmission rate were investigated. Monte Carlo N-Particle simulation (MCNP6.2) code is used for calculating the Thermal (2.53 × 10-8 MeV) and fast (2 MeV) neutron transmission ratio (I/I0) dependent on the sample thickness. The Phy-x program is employed for calculating the gamma-ray LAC, MAC, HVL, TVL, and MFP values. The calculated neutron shielding performance parameters of Ti50Cu30Zr15B5 alloy were compared with materials in the literature. It was found that Ti50Cu30Zr15B5 alloy demonstrated impressive physical characteristics, suggesting that it can serve as a promising alloy for neutron and gamma-ray shielding applications.
RESUMO
Due to their intrinsic stability and reduced toxicity, lead-free halide double perovskite semiconductors have become potential alternatives to lead-based perovskites. In the present study, we used density functional theory simulations to investigate the mechanical stability and band gap evolution of double perovskites Cs2AgBiX6 (X = Cl and Br) under an applied pressure. To investigate the pressure-dependent properties, the hydrostatic pressure induced was in the range of 0-100 GPa. The mechanical behaviors indicated that the materials under study are both ductile and mechanically stable and that the induced pressure enhances the ductility. As a result of the induced pressure, the covalent bonds transformed into metallic bonds with a reduction in bond lengths. Electronic properties, energy bands, and electronic density of states were obtained with the hybrid HSE06 functional, including spin-orbit coupling (HSE06 + SOC) calculations. The electronic structure study revealed that Cs2AgBiX6 samples behave as X-Γ indirect gap semiconductors, and the gap reduces with the applied pressure. The pressure-driven samples ultimately transform from the semiconductor to a metallic phase at the given pressure range. Also, the calculations demonstrated that the applied pressure and spin-orbit coupling of the states pushed VBM and CBM toward the Fermi level which caused the evolution of the band gap. The relationship between the structure and band gap demonstrates the potential for designing lead-free inorganic perovskites for optoelectronic applications, including solar cells as well as X-ray detectors.
RESUMO
In this work, NdCoO3 (NCO), Nd0.8Sr0.2CoO3 (NSCO) and Nd0.9Ca0.1CoO3 (NCCO) perovskite cobaltites were synthesised by mechanical alloying method. Structural evolutions, magnetic and electrical properties of these perovskite were systematically examined through X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray detection (SEM-EDX), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), vibration sample magnetometer (VSM) and impedance analyser (IA). The XRD and SEM results revealed that the microstructure of the perovskite materials changed during mechanical alloying. The average crystallite size of the perovskite materials was calculated by Debye Scherrer equation and was confirmed by TEM, and it was determined ~19 nm. From the VSM results, the all perovskites had soft ferromagnetic properties. IA measurements showed that relatively dielectric constants of the perovskites decreased with increasing frequency. Therefore, for the first time, nanostructured NCO, NSCO and NCCO perovskites exhibiting good properties were produced in only two steps which are milling and heating.