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This study determines the prevailing concentrations of 222Rn in twenty groundwater samples and primordial radionuclides in twelve soil samples collected from the surrounding area of the Rooppur Nuclear Power Plant (RNPP) in Bangladesh. The mean concentration of 222Rn, 226Ra, 232Th and 40K in the studied samples was found to be 4.42 ± 2 Bq/L (Water), 25.2 ± 5.3, 23.9 ± 6.3 and 317.1 ± 31.4 Bq kg−1 (Soil) respectively. Associated health hazards were estimated and compared with the respective safety limits recommended by international organizations. The present results may serve as the base values of naturally occurring radioactive materials in the vicinity of the RNPP in Bangladesh. [ABSTRACT FROM AUTHOR]

In this work, density functional theory (DFT)-based calculations were performed to compute the physical properties (structural stability, mechanical behavior, and electronic, thermodynamic, and optical properties) of synthesized MAX phases Hf 2 SB, Hf 2 SC, Hf 2 SeB, Hf 2 SeC, and Hf 2 TeB and the as-yet-undiscovered MAX carbide phase Hf 2 TeC. Calculations of formation energy, phonon dispersion curves, and elastic constants confirmed the stability of the aforementioned compounds, including the predicted Hf 2 TeC. The obtained values of lattice parameters, elastic constants, and elastic moduli of Hf 2 SB, Hf 2 SC, Hf 2 SeB, Hf 2 SeC, and Hf 2 TeB showed fair agreement with earlier studies, whereas the values of the aforementioned parameters for the predicted Hf 2 TeC exhibit a good consequence of B replacement by C. The anisotropic mechanical properties are exhibited by the considered MAX phases. The metallic nature and its anisotropic behavior were revealed by the electronic band structure and density of states. The analysis of the thermal properties-Debye temperature, melting temperature, minimum thermal conductivity, and Grüneisen parameter-confirmed that the carbide phases were more suited than the boride phases considered herein. The MAX phase's response to incoming photons further demonstrated that they were metallic. Their suitability for use as coating materials to prevent solar heating was demonstrated by the reflectivity spectra. Additionally, this study demonstrated the impact of B replacing C in the MAX phases., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

In this article, ab initio calculations of unexplored Ti 2 PB 2 , Zr 2 PbB 2 , and Nb 2 AB 2 [A = P, S] were performed wherein Ti 2 PB 2 along with its 211 boride phase Ti 2 PB was predicted for the first time. The stability was confirmed by calculating the formation energy, phonon dispersion curve, and elastic stiffness constants. The obtained elastic constants, elastic moduli, and Vickers hardness values of Ti 2 PB 2 , Zr 2 PbB 2 , and Nb 2 AB 2 [A = P, S] were found to be significantly larger than those of their counterparts 211 borides and carbides. The studied compounds are brittle, like most MAX and MAB phases. The electronic band structure and density of states revealed the metallic nature of the titled borides. Several thermal parameters were explored, certifying the suitability of Ti 2 PB 2 , Zr 2 PbB 2 , and Nb 2 AB 2 [A = P, S] to be used as efficient thermal barrier coating materials. The response of Ti 2 PB 2 , Zr 2 PbB 2 , and Nb 2 AB 2 [A = P, S] to the incident photon was studied by computing the dielectric constant (real and imaginary parts), refractive index, absorption coefficient, photoconductivity, reflectivity, and energy loss function. In this work, we have explored the physical basis of the improved thermomechanical properties of 212 MAX phase borides compared to their existing carbide and boride counterparts., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Boron-rich chalcogenides have been predicted to have excellent properties for optical and mechanical applications in recent times. In this regard, we report the electronic, optical, and mechanical properties of recently synthesized boron-rich chalcogenide compounds B 12 X (X = S and Se) using density functional theory for the first time. The effects of exchange and correlation functionals on these properties are also investigated. The consistency of the obtained crystal structure with the reported experimental results has been checked in terms of lattice parameters. The considered materials are mechanically stable, brittle, and elastically anisotropic. Furthermore, the elastic moduli and hardness parameters are calculated, which show that B 12 S can be treated as a prominent member of the hard materials family compared to B 12 Se. The origin of differences in hardness is explained on the basis of density of states near the Fermi level. Reasonably good values of fracture toughness and the machinability index for B 12 X (X = S and Se) are reported. The melting point, T m , for the B 12 S and B 12 Se compounds suggests that both solids are stable, at least up to 4208 and 3577 K, respectively. Indirect band gaps of B 12 S (2.27 eV) and B 12 Se (1.30 eV) are obtained using the HSE06 functional. The energy gaps using local density approximation (LDA) and generalized gradient approximation (GGA) are found to be significantly lower. The electrons of the B 12 Se compound show a lighter average effective mass than that of the B 12 S compound, which signifies a higher mobility of charge carriers in B 12 Se. The optical properties such as the dielectric function, refractive index, absorption coefficient, reflectivity, and loss function are characterized using GGA-PBE and HSE06 methods and discussed in detail. These compounds possess bulk optical anisotropy, and excellent absorption coefficients in the visible-light region along with very low static values of reflectivity spectra (range of 7.42-14.0% using both functionals) are noted. Such useful features of the compounds under investigation show promise for applications in optoelectronic and mechanical sectors., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)