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Lead‐free double perovskites are unique materials for transport and optoelectronic applications that use clean resources to generate energy. Using first‐principle computations, this study thoroughly investigates the structural, thermoelectric, and optical attributes of A2TlAgF6 (A = Rb, Cs). Tolerance factor and formation energy estimates are used to verify that these materials exist in the cubic phase. Elastic constants with high melting temperature values are ductile when evaluated for mechanical stability using the Born stability criterion. The optical absorption band is adjusted from 2 to 4 eV via band gaps of 1.88 and 1.99 eV, as indicated by band structures. Analysis of optical properties reveals perfect absorption in the visible spectrum, whole polarization, and low optical loss. Furthermore, thermoelectric properties are assessed at 300, 500, and 700 K in the range of −0.5 to 3 eV for chemical potential (μ). The materials exhibit significant improvements in the Figure of Merit scale due to their elevated electrical conductivity, Seebeck coefficient, and extremely low thermal conductivity values. [ABSTRACT FROM AUTHOR]

The double perovskites are become the emerging aspirant to fulfill the demand of energy. Therefore, the optoelectronic, elastic and transport characteristics of Ba2XMoO6 (X = Zn, Cd) are addressed systemically. The elastic constants show the mechanical stability. The nature of Ba2ZnMoO6 is brittle and Ba2CdMoO6 is ductile with large values of Debye temperature covalent bonding. The electronic band structures exhibit band gaps of 2.81 and 2.98 eV, which increase their importance for optoelectronic applications. The absorption of light energy, optical loss, refractive index, polarization of light energy are addressed in the energy range zero to 14 eV. Furthermore, thermoelectric characteristics are computed against chemical potentials at 300, 600, and 900 K. The chemical potential decides the p‐type nature, with holes as majority carriers. The increasing temperature increases the power factor and figure of merit. Therefore, the optoelectronic and thermoelectric characteristics reveals the importance of studied DPs for energy applications. [ABSTRACT FROM AUTHOR]

In this study, structural, electronic, optical, thermoelectric, and thermodynamics properties of vacancy‐ordered double perovskites Rb2XCl6 (X = Se, Ti) were explored theoretically. The results revealed that Rb2SeCl6 and Rb2TiCl6 are indirect band gap (Eg) semiconductors with Eg values of 2.95 eV, and 2.84 eV respectively. The calculated properties (phonons, elastic constant, Poisson's ratio, and Pugh's ratio) revealed that both materials are dynamically and chemically stable and can exhibit brittle (Rb2SeCl6) and ductile (Rb2TiCl6) nature. From the analysis of optical parameters, it was noticed that the refractive index of the materials has a value of 1.5–2.0 where light absorption was found from the visible to the ultraviolet region. The thermoelectric properties determined by using the BoltzTrap code demonstrated that at room temperature, the Figure of merit (ZT) was found to be 0.74 and 0.76 for Rb2SeCl6 and Rb2TiCl6, respectively. Despite a moderate value of ZT in such materials, further studies might explore effective methods for tuning the electronic band gap and improving the thermoelectric response of the material for practical energy production applications. [ABSTRACT FROM AUTHOR]

The variant double perovskites are considered novel materials for solar cells and optoelectronic applications. Here, we explored electronic, mechanical, and optical characteristics of Cs2SeX6 (X = Cl, Br, I) by density functional theory (DFT) analysis. The tolerance factor between 0.97–1.0 signifies the structural stability of the investigated compounds while thermodynamic and mechanical stabilities were ensured by positive frequencies of phonon dispersion as well as elastic constants. Moreover, the Poisson and Pugh's ratios are explored for brittle and ductile behavior. The Debye and melting temperatures have also been reported through mechanical analysis. The tuning of the bandgap takes place from 3.10 to 2.64 eV and then 1.15 eV by substitution of Cl with Br and I, respectively. The optical spectra show a shift in absorption region from ultraviolet-to-visible. In addition, the low light reflection and optical energy loss range (0.0–3.0 eV) promises potential of the studied potential for solar cells and optoelectronics uses. [ABSTRACT FROM AUTHOR]

Abstract: Storage capacity of carbon dioxide (CO2) in deep saline aquifers is a challenging task. However, an assessment must be performed to determine whether there is sufficient capacity in a storage site for any CO2 sequestration project. We evaluated the CO2 storage capacity for a simplified reservoir system, which the layered potential storage formations are overlaid by sealing cap rock. In this paper, we aim to investigate numerically the storage of CO2 at supercritical conditions in deep saline aquifer reservoirs. Numerical simulations were carried out on non-deformable saturated porous material inside a vertical enclosure, assumed to be impermeable and isolated on three sides. The porous medium is considered to be homogeneous and isotropic with constant thermo-physical properties with the exception of the density of the fluid varying according to Boussinesq approximations. A dynamic model assuming that flow is two-dimensional and obeying to Darcy's law for motion has been used. We assume also that the thermal equilibrium assumption is valid. The set of the conservation equations along with the appropriate initial and boundary conditions have been resolved numerically by the classical finite volume method [1]. Spatio-temporal variations of different state variables such as pressure, velocity, temperature and concentration were numerically simulated and plotted versus different controlling parameters particularly, thermal and solutal Rayleigh numbers and Lewis number. Great attention was paid to examine the sensitivity of heat and mass transfer rates according to the reservoir form and the operating conditions. [Copyright &y& Elsevier]

The present communication aims to provide a theoretical examination of the structural, electronic, optical, transport, and mechanical characteristics of Li 2 AgAsX 6 (X = Cl, Br, I) to check their potential for optoelectronic and thermoelectric applications. The structural analysis reveals their cubic symmetry, and their structural and thermodynamic stability is verified through assessments of their tolerance factors (0.96, 0.94, and 0.93) and formation energies (-3.63, -3.10, and -2.16 eV). Their mechanical stability and ductile nature are confirmed using elastic constants, Poisson's ratio, and Pugh's criterion. Analysis of the band structure exhibits bandgaps of 0.86, 0.56, and 0.22 eV for Cl-, Br- and I-based compositions. Analysis of their optical behavior is carried out in terms of complex dielectric constant, complex refractive index, optical conductivity, reflectivity, and loss, providing better insight into material characteristics. The highest absorption in the infrared region underscores their prospects as infrared detectors. Additionally, the materials exhibit high electrical conductivity, and ultra-low lattice thermal conductivity with a considerable figure of merit, highlighting their feasibility for thermoelectric devices., Competing Interests: On behalf of all authors, the corresponding author states that there is no conflict of interest., (This journal is © The Royal Society of Chemistry.)

In ferromagnetic semiconductors, the coupling of magnetic ordering with semiconductor character accelerates the quantum computing. The structural stability, Curie temperature (T c ), spin polarization, half magnetic ferromagnetism and transport properties of ZnX 2 Se 4 (X = Ti, V, Cr) chalcogenides for spintronic and thermoelectric applications are studied here by density functional theory (DFT). The highest value of T c is perceived for ZnCr 2 Se 4 . The band structures in both spin channels confirmed half metallic ferromagnetic behavior, which is approved by integer magnetic moments (2, 3, 4) μ B of Ti, V and Cr based spinels. The HM behavior is further measured by computing crystal field energy ΔE crystal , exchange energies Δ x ( d ), Δ x ( pd ) and exchange constants (N o α and N o β). The thermoelectric properties are addressed in terms of electrical conductivity, thermal conductivity, Seebeck coefficient and power factor in within a temperature range 0-400 K. The positive Seebeck coefficient shows p-type character and the PF is highest for ZnTi2Se4 (1.2 × 10 11 W/mK 2 ) among studied compounds.