Energy Absorption Coefficient Research Articles

METHODOLOGY FOR EXPERIMENTAL RESEARCH ON THE DISTRIBUTION OF ENERGY IN THE ELEMENTS OF THE «VIBRATION MACHINE – COMPACTING CONCRETE MIXTURE» SYSTEM

The paper presents a methodology for experimental research on the distribution of energy in the elements of a vibra-tion machine for compacting concrete mixtures. The development of this methodology is based on a thorough analy-sis of existing research methods and the determination of energies in mechanical systems and media. Within the general system of the "vibration machine – compacting concrete mixture," the following subsystems were identified: bearings of the vibration exciter, supports, vibration dampers, reactive and active masses, including the form mass and the compacting concrete mixture. Specific research methods for energy dissipation were determined for each of the mentioned subsystems, preceding relevant modeling. Energy dissipation depends on many factors: the composi-tion and structure of the material, cyclic deformation and stresses arising from the medium’s exposure, the type and parameters of the load, the duration of cyclic deformation, and more. The evaluation criterion for energy dissipa-tion in media is the energy absorption coefficient, which expresses the ratio of energy used to perform the techno-logical process of compaction to the potential energy. The ratio of these energies is considered an independent material characteristic, determined experimentally, taking into account actual technological and operational fac-tors. It was found that the following main methods are used to evaluate energy parameters: phase, damping oscilla-tions, hysteresis loops, energy, and resonance methods. The paper substantiates the methodology for experimental research of parameters and energy indicators of concrete mixture compaction processes. Two models—discrete and continuous—were used in the simulation of these processes.

Evaluation of gamma radiation shielding characteristics of FeNbSc-based alloys

This study evaluated the radiation shielding features and interaction characteristics of FeNbSc-based alloy by separately doping the base alloy (FeNbSc) with Si, Ge, Ga, and Al for application in nuclear reactor design and radioactive waste confinement. The variations of Mass attenuation coefficient (MAC), Mass energy-absorption coefficient (MEAC), Effective atomic number (Zeff), effective electron densities (Neff), Specific gamma ray constant (Γ), Gamma dose rate (Dτ), exposure buildup factors (EBF) and Energy absorption buildup factors (EABF) at different photon energies were evaluated using WinXCOM computer program. Observation from results showed that FeNbScGe alloy displayed the highest shielding characteristics among all investigated alloy samples across all photon energies. The MAC of the prepared alloy samples was significantly higher than some recently developed commercial SCHOTT radiation shielding composites at 0.662 and 1.25 MeV gamma energy. The EBF and EABF of the studied alloy samples varied to modifying elements (Si, Ge, Ga, and Al) in the investigated samples. The MEAC values of the FeNbScGe alloy investigated samples were higher than those of other investigated alloys. Hence, FeNbScGe alloy should be considered for nuclear reactor design and radioactive waste confinement.

Dual virtual non-contrast imaging: a Bayesian quantitative approach to determine radiotherapy quantities from contrast-enhanced DECT images

Objective.Contrast agents in computed tomography (CT) scans can compromise the accuracy of dose calculations in radiation therapy planning, especially for particle therapy. This often requires an additional non-contrast CT scan, increasing radiation exposure and introducing potential registration errors. Our goal is to resolve these issues by accurately estimating radiotherapy parameters from dual virtual non-contrast (dual-VNC) images generated by contrast-enhanced dual-energy CT (DECT) scans, while accounting for noise and variability in tissue composition.Approach.A new Bayesian model is introduced to estimate dual-VNC Hounsfield units from contrast-enhanced DECT data. The model defines a prior distribution that describes tissue variations in terms of elemental compositions and mass densities. Multiple reference tissues are used to estimate variations across human tissues. A likelihood distribution is also defined to model the noise contained in CT data. The model is thoroughly validated in a simulated environment including 12 virtual patients under low and high iodine uptake scenarios, while incorporating noise and beam hardening effects. The eigentissue decomposition technique is used to derive elemental compositions and parameters critical for radiotherapy from the dual-VNC images, such as electron density (ρe), particle stopping power (SPR), and photon energy absorption coefficient (EAC).Main results.The proposed method yields accurate voxelwise estimations forρe, SPR, and EAC, with root mean square errors of 3.09%, 3.14%, and 1.34% for highly-enhanced tissues, compared to 5.93%, 6.39%, and 17.11% when the presence of contrast agent is ignored. It also demonstrates robustness to systematic shifts in tissue composition and bandwidth variations in the prior distribution, resulting in overall uncertainties down to 1.13%, 1.33%, and 0.86% forρe, SPR, and EAC in soft tissues; 1.17%, 1.32%, and 1.34% in enhanced soft tissues; and 4.34%, 4.00%, and 2.50% in bones.Significance.The proposed method accurately derives radiotherapy parameters from contrast-enhanced DECT data and demonstrates robustness against systematic errors in reference data, highlighting its potential for clinical use.

Gamma attenuation, buildup factors, and radiation shielding performance of CaO-borosilicate glasses

This paper investigates the gamma attenuation properties and radiation shielding performance of CaO-B2O3-SiO2 glasses. Through theoretical analysis, the mass attenuation coefficient (μ/ρ) and its corresponding mass energy-absorption coefficient (μen/ρ) of the selected glasses are computed across various photon energies. The other related parameters such as dose rate, effective atomic number, and buildup factor are also determined and discussed in details. The results reveal that there is a significant variation in the attenuation behaviour with changing glass composition and photon energy. As the photon energy increases beyond a certain point (around 0.3 MeV in this table), the values of (μ/ρ) tend to plateau or decrease slowly. Furthermore, we provide a comparative analysis of the mass attenuation coefficient of the investigated glasses with those of commercial SCHOTT's radiation shielding glasses, offering insights into their relative shielding efficacy. This study contributes to the understanding of the radiation shielding capabilities of CaO-B2O3-SiO2 glasses, offering potential applications in diverse fields requiring effective gamma radiation protection.

Dynamic Energy Performance and Pore Structure of CGSC under Sulfate Attack: An SHPB-Based Study

This study aims to evaluate the durability of using coal gangue as a substitute for natural aggregates in shotcrete linings for coal mine roadways, addressing environmental concerns from resource consumption and coal gangue accumulation. The support structures of coal mine roadways endure dynamic loads and sulfate erosion during service, making it crucial to assess the long-term stability of these materials in such complex environments. Accordingly, coal gangue shotcrete (CGSC) specimens were immersed in Na2SO4 solution, and a Split Hopkinson Pressure Bar (SHPB) system was used to examine the impact of erosion on their dynamic mechanical properties. The results indicate that in the early stages of erosion (0–30 days), the dynamic compressive strength (DCS) of CGSC increased significantly. Under a condition of 0.06MPa, the DCS rose from 31.8MPa to 45.2MPa, representing a 42% increase. Similarly, under 0.10MPa, it increased from 93.9MPa to 99.0MPa, a 5.4% improvement. However, in the mid-to-late stages of erosion (30–120 days), the DCS gradually declined. Under 0.06MPa, it dropped to 28MPa (a decrease of 38%), and under 0.10MPa, it fell to 62.1MPa (a decrease of 37.3%). Microscopic structural characterizations conducted using NMR, XRD, and SEM revealed that the expansion and rupture of erosion products led to the propagation of microcracks, which contributed to the performance degradation. Additionally, the study analyzed the relationship between pore structure changes, fractal dimensions (D1 and D2), and the energy absorption coefficient (λ). A dynamic strength model was developed, quantitatively linking the duration of sulfate erosion to the energy dissipation rate. This research provides theoretical support for optimizing the sulfate erosion resistance of CGSC and enhancing the durability and safety of mining tunnel structures.

DFT assessment on the future prospects of inorganic lead-free halide double perovskites Cs2ABI6 (AB: GeZn, SnBe) for energy conversion technologies

In this study, we employed density functional theory (DFT) calculations to investigate the structural, elastic, electronic, optical, and thermoelectric properties of Cs2ABI6 (AB: GeZn, SnBe) halide double perovskites (HDPs). We employed the full-potential linear augmented plane-wave (FP-LAPW) method, incorporating the generalized gradient approximation (GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ) approach for the exchange-correlation potential. We found that the HDPs are stable in a cubic structure (space group Fm-3m), as indicated by phase stability analysis, formation energies, tolerance factor, and elastic constants. The compounds exhibits ductile behavior, as assessed by Poisson's and Pugh's ratios. The electronic band structures of Cs2GeZnI6 and Cs2SnBeI6 exhibit indirect band gaps (X-L) of 1.124 eV and 1.551 eV, respectively, as calculated using the TB-mBJ approximation. Optical spectra were evaluated over the 0–13 eV energy range, including the dielectric functions, extinction coefficient, electron energy loss, refractive index, optical conductivity, reflectivity, and absorption coefficient. Additionally, we calculated thermoelectric parameters across a range of chemical potentials and temperatures to assess their suitability for thermoelectric applications. Our results suggest that these compounds are highly promising candidates for both optoelectronic and thermoelectric devices.

Structural, electronic, optical, mechanical, and phononic bulk properties of tetragonal trirutile antimonate MSb2O6 (M = Fe, Co, Ni, or Zn): a first-principles prediction for optoelectronic applications

Abstract This work does an extensive analysis of the optoelectronic and mechanical properties of the tri rutile structure type 3d transition metal Antimonate MSb2O6 (M = Fe, Co, Ni, or Zn), for the first time, utilizing the pseudo-potential plane wave approach within the density functional theory framework. When calculating the structural, optical, and mechanical properties, the exchange–correlation interactions were studied using the GGA-PBE functional, whereas when computing electronic, it is analyzed using the HSE06 hybrid functional. The equilibrium lattice parameters exhibit good agreement with the available experimental results. The electronic properties were estimated using the GGA-PBE and HSE06 functionals. Based on the calculated electronic properties with the GGA-PBE functional, the FeSb2O6, CoSb2O6, and NiSb2O6 materials exhibit metallic behavior with energy gap values of 0 eV, while ZnSb2O6 is a semiconductor with a narrow direct band gap (Γ–Γ) of 0.5 eV. Furthermore, the computed band gaps using the HSE06 functional are 0 eV, 0 eV, 1 eV (Γ–Γ), and 4 eV (Γ–Γ) for FeSb2O6, CoSb2O6, NiSb2O6, and ZnSb2O6, respectively. Density of states diagrams were used to gain deeper insights into the characteristics of the energy bands. The optical properties of these compounds, such as the dielectric function, energy loss function, conductivity, reflectivity, refractive index, and absorption coefficient were investigated over the energy range of 0 to 40 eV. The materials exhibited a high absorption coefficient and a significantly low reflectivity within the UV–vis energy spectrum. The negative cohesive energy Ecoh implies the chemical (thermodynamic) stability of the trirutile MSb2O6 (M = Fe, Co, Ni, or Zn). Mechanical stability is confirmed by applying the Born stability criteria using elastic constants (Cij). The absence of imaginary frequencies in the phonon spectrum calculations confirms the dynamic stability of the studied compounds. These results are consistent with previous experimental research on these materials in photocatalysis and gas sensor applications. On the other hand, these compounds possess exceptional high and broad optical absorption UV range, making them suitable for use in next-generation ultraviolet photodetectors.

First principles calculations of physical properties of the CeCu2Si2 material

Using local density approximation functional computations, LSDA (local spin density approximation) and mBJ (modified Becke-Johnson) for exchange-correlation interactions, we examined the combination CeCu2Si2, concentrating on its many physical properties. This work used the WC-GGA method to compute the elastic characteristics of CeCu2Si2 material, and the results indicate that unstrained CeCu2Si2 is more brittle. The density of states exhibits the metallic character of the chemical, in agreement with the inference made from the band structure. We also assessed several optical characteristics, such as real and imaginary optical conductivity, electronic energy loss, absorption coefficient, refractive index, and extinction coefficient. We also looked at the electronic components of thermal conductivity, electrical conductivity, Seebeck coefficient, and electronic conductivity. The compound's Seebeck coefficient values are negative, indicating p-type behavior. A thorough analysis of the data is presented, along with important details regarding the CeCu2Si2 compound's characteristics.

Gamma radiation shielding and interaction properties of MoO3-Doped cadmium zinc lithium-borate glasses

This study, theoretically examined the impact of MoO3 addition on gamma radiation shielding properties of cadmium zinc lithium-borate (BCZLMx) glasses to find the optimal quantity of molybdenum oxide (MoO3) needed for a stable glass matrix with excellent gamma shielding capabilities. Gamma radiation transmission parameters that include Mass attenuation coefficient, Mass energy absorption coefficient, Equivalent atomic number, Effective electron density, Dose rate, Exposure buildup factors and Energy absorption buildup factor were evaluated using FLUKA and XCOM computer programs. Results showed that 60B2O3-20CdO-10ZnO-8Li2O-2MoO3 (BCZLM5) was the most stable and efficient glass sample for X-rays and gamma radiation shielding across all photon energy ranges. Hence, BCZLM5 should be deployed for X-rays and gamma radiation shielding to provide maximum protection and exceptional safety for workers in hospital X-ray rooms and nuclear installations against ionizing radiation.

Simulation model to enhance Bragg reflector assisted GeSn SACM-SPAD performance for 1550 nm LIDAR applications in autonomous vehicles

A safe 3-D lidar sensor for autonomous vehicle creates a high demand on 1550 nm SPADs detectors. Due to the limitation of the energy band gab and absorption coefficient of Si and Ge, their photodetectors have low efficiency at the 1550 nm wavelength. Doping Ge with Sn reduces its bandgap and enables higher efficiency in this range while adding Bragg reflector represents a smart way to increase absorption area effective thickness. Here a simulation model for Ge(1-x)Snx SACM SPAD is proposed to work as a 1550 nm laser detector. Two Bragg reflectors are built using Si\\SiGe and Si\\SiGeSn layers. Results show a significant enhancement on detector optical properties. PDP reaches 38 % at room temperature and the increase in Pdp due to Bragg reflector reaches 66 %. Although DCR also increases, it can be handled with proper dead time configuration.

Gamma attenuation and radiation shielding performance of CaCu3B2Re2O12 (B[dbnd]Mn, Fe, Co, and Ni) perovskites

In order to identify the importance of perovskites in nuclear science, studies aimed at obtaining the radiation interaction quantities of perovskites are essential. This study computed and analyzed the gamma photon interaction parameters of CaCu3B2Re2O12 (BMn, Fe, Co, and Ni) perovskites to reveal their shielding potentials and comparative advantages against traditional shielding materials. Four samples of ferrimagnetic quaternary perovskites whose chemical structures are summarized as CaCu3B2Re2O12 (BMn (CCMRO1), Fe (CCMRO2), Co (CCMRO3), and Ni (CCMRO4)) were considered for their gamma interaction quantities. The values of mass attenuation coefficient (μρ) was calculated with XCOM and they were in the range of 0.0552 cm2/g–0.4162 cm2/g for CCMRO1, 0.0553 cm2/g–0.4165 cm2/g CCMRO2, 0.0552 cm2/g–0.4148 cm2/g for CCMRO3, and 0.0555 cm2/g–0.4163 cm2/g for CCMRO4. The values of effective atomic number and electron density was within the range 21.38–43.38 and 2.84 x 1023 electrons/g −5.62 x1023 electrons/g, respectively. The trend of the mass energy absorption coefficients of the perovskites was also found to be in the same order as the mass attenuation coefficient. CCMRO3 has the highest photon energy absorptive ability among the perovskites while CCMRO2 has the least capacity. Also, the gamma dose rates in15 mm thick of CCMRO1, CCMRO2, CCMRO3, and CCMRO4 for 1.25 MeV are about 1446 kR/h, 1449 kR/h, 1453 kR/h, and 1446 kR/h, respectively. Comparatively, the values of the exposure and energy absorption buildup factors were almost the same for the perovskites at the same energy and optical depth. The investigated perovskites had higher mass attenuation coefficients that standard shielding glasses. The perovskites can be used for shielding or any other radiation absorption roles in radiation science and technology, especially for photons at low energies.

Investigation of the structural, electronic, magnetic, and optical properties of the double perovskite oxide semiconductor La2NiMnO6: Ab initio calculations by using GGA-PBE and GGA + mBJ approximations

In this paper, we examined the La2NiMnO6 double perovskite oxide semiconductor materials, our treatment included the structural, electronic, magnetic, and optical characteristics by utilizing the density functional theory, which was performed in the Wien2k software. The exchange–correlation potential was carried out in combination with the GGA-PBE (Perdew Burke Ernzerhof Generalized Gradient Approximation), and GGA + mBJ (modified Becke and Johnson) was used for the exchange–correlation potentials. The results suggest that the compound La2NiMnO6 exhibits in a ferrimagnetic state. It was also found that the stable ground state of the compound is ferrimagnetic. The results demonstrate that La2NiMnO6 has a band gap whose spin-up value is 0 eV and spin-down (dn) value is 2.86 eV (GGA-PBE), with up values is 0 eV and dn value being of 3 eV (GGA + mBJ). We also explored different optical properties, among them electron energy loss, absorption coefficient, real and imaginary dielectric tensor, and real and imaginary optical conductivity.

Theoretical modeling of feedstock-laser energy interaction in directed energy deposition with simultaneous wire and powder feeding

The Laser-based Directed Energy Deposition (L-DED) process is widely employed for the fabrication of numerous metallic parts. It also stands out as a crucial additive manufacturing (AM) technique for creating metal matrix composites (MMCs) reinforced with ceramic particles. The simultaneous deposition of wire and powder feedstocks into the created melt pools on the substrate surface proves advantageous in overcoming the limitations associated with mixed powders in powder deposition alone. The strategy of coaxial wire and powder deposition (CWP-DED) allows for more efficient construction of MMCs with complex geometries and desirable properties. Nevertheless, CWP-DED is a complex multi-phase deposition process that involves highly dynamic interactions among laser beams, wire, and powder particles, influencing laser energy distribution and absorption during the process. This work aims to develop a theoretical model to advance the fundamental understanding of the absorbed and lost laser beam energy by the fed wire and powders in CWP-DED before entering the melt pool. Laser energy absorption coefficients can be calculated based on the Step Wise Heating method to determine the final temperature of the powder particles and wire before entering the melt pool. The experimental validation of the proposed model requires a power meter that fits the CWP-DED system with six inclined laser beams, which is not commercially available so far, to measure the actual output power with and without wire and powder feeding. Consequently, this work presents a detailed explanation of the experimental procedure desired to measure the absorption coefficients of the wire and powder feedstocks and how to validate the proposed model as a future research endeavor. This model plays a vital role in predicting and understanding the amount of heat transferred into the melt pool, which lays a foundation for understanding the complicated melt pool thermodynamics that directly govern the microscopic characteristics and macroscopic properties of the as-built parts.

Investigation of structural, elastic, electronic, and optical properties of lead-free double perovskites Cs2XBeBr6 (X = Ge, Sn): a first-principles DFT study.

In this study, the structural, elastic, electronic, and optical properties of Cs2GeBeBr6 and Cs2SnBeBr6 halide double perovskites (HDPs) were investigated using density functional theory (DFT) calculations. Notably, the Tran-Blaha modified Becke-Johnson (TB-mBJ) method was employed to predict indirect band gaps of 2.434 eV for Cs2GeBeBr6 and 2.855 eV for Cs2SnBeBr6. The stability of these compounds in a cubic (Fm-3m) structure was confirmed through formation energy, cohesive energy, tolerance factor, and elastic constants. Furthermore, the ductile nature of the materials was demonstrated through Poisson's and Pugh's ratios. Our optical property analysis, spanning the 0-13 eV energy range, revealed key insights into the dielectric functions, extinction coefficient, electron energy loss, refractive index, optical conductivity, reflectivity, and absorption coefficient. These results highlight the potential of Cs2GeBeBr6 and Cs2SnBeBr6 for future optoelectronic and photovoltaic applications. In this investigation, we employed density functional theory (DFT), implemented using the Wien2k package. The exchange and correlation potentials were treated using the generalized gradient approximation (GGA) and the Tran-Blaha modified Becke-Johnson (TB-mBJ) method. To evaluate dynamic stability, we analyzed the phonon band structures using the CASTEP code.

Broadband and high-efficiency acoustic energy harvesting with loudspeaker enhanced by sonic black hole

It is well-known that acoustic energy sources can be seen as a promising alternative energy resource by using acoustic energy harvester (AEH) which can transform sound energy into usable electrical power. However, the current AEHs have been restricted by their narrow bandwidths and low energy conversion efficiencies. In this study, a broadband and high efficient AEH is presented. The proposed AEH comprises an open-end sonic black hole (SBH) structure and an electrodynamic loudspeaker. The sound pressure is amplified through the open-end SBH structure, then the loudspeaker is used as electricity generator to convert acoustic energy into electric energy. The open-end SBH is a cylindrical tube with an array of regularly-spaced rigid-walled thin rings. The inner radii of the SBH rings are quadratically decreasing and the SBH effect can be obtained. The model for energy harvesting and sound absorption performance of the proposed AEH is then presented. Finally, the open-end SBH is fabricated by 3D printing apparatus. A prototype of the AEH is designed and tested by using an impedance tube. The energy conversion efficiency and absorption coefficient from calculation and experiment show a reasonable agreement. The proposed AEH can convert 11 % of total incident sound energy from 50 Hz to 800 Hz. The maximum energy conversion efficiency can achieve 65 % at 425 Hz under optimal resistance load. Furthermore, the broadband sound absorption can also be achieved by using the proposed AEH.

Unveiling the DFT perspectives on structural, elastic, electronic, optical and thermal properties of XMn2As2 (X = Ca, Sr)

A comprehensive first-principles investigation of XMn2As2 (X = Ca, Sr) materials using Density Functional Theory (DFT) have used in this study. Variety of physical attributes, including thermal, mechanical, electronic, optical and elastic anisotropic properties are explored. Lattice parameters and crystal structures showed excellent agreement with previous experimental data. The findings reveal that CaMn2As2 and SrMn2As2 exhibit notable elastic anisotropy, and satisfy the Born criteria for mechanical stability. The calculated elastic moduli are consistent with previously published values. The metallic nature of these compounds is demonstrated through band structure and density of states (DOS) analyses. Optical property analyses, including energy loss function, electrical conductivity, reflectivity, dielectric constant, refractive index, and absorption coefficient, highlight the potential of these materials for optoelectronic and photovoltaic applications. Notably, SrMn2As2 displays an exceptionally low minimum thermal conductivity compared to CaMn2As2, indicating its potential as a superior Thermal Barrier Coating (TBC) material.

Gamma attenuation and buildup factors of GeO2-Ga2O3–Gd2O3 transparent glass ceramics for shielding applications

While gamma radiation presents significant hazards, the development of reliable shielding materials is demanded. This research study aims to investigate the gamma attenuation and buildup factors of transparent glass ceramics with the composition described by the formula of 99 [60GeO2 + (40-y)Ga2O3 + yGd2O3] +1Nd2O3, with y = 13,15,17, and 19 mol%. The basic gamma attenuation factor, namely mass attenuation coefficient (MAC), is calculated theoretically by using WinXCOM. By using MAC values, obtained by WinXCOM, we estimated the other gamma attenuation factors such as effective atomic number (Zeff) and electron density (Neff). Moreover, the absorption parameters, such as mass energy-absorption coefficient (MEAC), and buildup factors are also evaluated. It is found that the highest Zeff values are observed at 0.015 MeV with the values of 37.648, 38.618, 39.577, and 40.528 for GN1, GN2, GN3, and GN4 respectively. Moreover, the Gd2O3 content has a significant effect to improve the attenuation capacity of the studied samples.

Simulation of the Effect of Dy3+ Dopant on the Mass Energy Absorption Coefficient and Relative Energy Response of TLD Made from Lithium Magnesium Borate Using MCNP

Thermoluminescence dosimeter (TLD) is widely used as a personal and medical dosimeter. Several TLD materials show the characteristics of mass energy absorption coefficient and energy response relative to ICRU (International Commission on Radiation Units and Measurements) issue material as an equivalent material for human body soft tissue. This research aims to analyze the effect of Dy3+ dopant on the mass-energy absorption coefficient and relative energy response of Lithium Magnesium Borate (LMB) materials. The simulation was carried out using Monte Carlo N-Particle (MCNP) software. Calculations based on simulation and theoretical results will be compared statistically using paired t-tests. The study showed that adding a Dy3+ dopant to TLD material made of Lithium Magnesium Borate (LMB) only affected the mass-energy absorption coefficient and relative energy response for low radiation energy. Adding Dy3+ dopant increased the mass energy absorption coefficient and relative energy response in a reasonably small value. Based on these results, LMBDy3+ produces a better mass-energy absorption coefficient value for TLD materials. The results of the statistical tests show a significant difference in the mass energy absorption coefficient value. At the same time, there is no significant difference between the simulation results and theoretical calculations for the relative energy response.

Computational study of the structural, mechanical, electronic, optical and thermal properties of BaLiX (X =P, As, Sb) perovskites

This study explores the structural, optical, mechanical, electronic, and thermal characteristics of ionic semiconductor compounds BaLiX (X = P, As, Sb) using Density Functional Theory (DFT). A comprehensive analysis of BaLiX (X = P, As, Sb) is conducted, proving that the estimated and observed lattice parameters coincide well and confirming mechanical stability through elastic stiffness constants. Electronic band structures reveal direct bandgap semiconductor properties with values of 0.70 eV, 0.30 eV, and 0.95 eV for BaLiP, BaLiAs, and BaLiSb, respectively, suggesting specific applications such as mid-infrared photodetectors, terahertz devices, and near-infrared sensors. Optical property analyses, including energy loss function, reflectivity, refractive index, and absorption coefficient, highlight the potential of these materials for optoelectronic and photovoltaic applications. Despite elastic anisotropy, optical anisotropy remains minimal. The materials exhibit potential for use as thermal barrier coatings (TBC) due to their comparatively lower Debye temperature (D), minimum thermal conductivity (Kmin) and lattice thermal conductivity (kph). Moreover, heat capacity calculations and thermal coefficient of expansion are also calculated.

Evaluating the Kerma coefficients relevant to various water-equivalent materials at different photon energies

To investigate the water equivalency of some solid phantoms, relevant Kerma coefficients were determined through both Monte Carlo (MC) simulation and analytical approaches over a wide range of photon energies ranging from 1 keV to 20 MeV.MCNPX MC Code was employed to simulate the Kerma coefficients for A-150, PMMA, Polystyrene, Solid Water (RMI 457), Solid Phantom (RW3), Virtual water, Solid Water (WT1), and Water Equivalent (Wte) solid phantoms. Kerma coefficients were also theoretically calculated using the mass energy absorption coefficients at different photon energies ranging from 1 keV to 20 MeV. Obtained Kerma coefficients for considered solid phantoms were also compared with those of water to find which material shows the best water-equivalency.Calculated Kerma coefficients by MC simulation were in a good agreement with those calculated via an analytical method which no statistically significant differences were observed among simulated and analytically calculated Kerma coefficients (p-value>0.05). Solid water (RMI 457) showed the best water-equivalency among studied plastic phantoms for radiology and radiotherapy quality assurance purposes. From the results, the Kerma coefficients for solid phantoms are highly dependent on photon energy.