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Zintl materials have received enormous attention in recent time due to their unique structure and thermoelectric efficiency. In this work, quaternary Zintl compounds LaAgZnX2 (X = P, As) have been comprehensively investigated using the FP-LAPW + lo method through first principles approximation. The dynamic stability of the samples is performed through phonon analysis. Birch–Murnaghan equation of states is used to determine ground state parameters. The lattice constant increases while formation energy and bulk modulus B(GPa) decrease by anion replacement from P to As. Band structure calculation shows that LaAgZnP2 is an indirect bandgap semiconductor while LaAgZnAs2 is a direct bandgap semiconductor. The density of states (DOS) demonstrates that the valence band (V.B) is mainly comprised of Zn-d and X-p states while the La-f state is in the conduction band (C.B) along with the minor contribution of the La-d state. Substantial absorption is observed in the low-frequency ultraviolet and visible spectrums for these compounds. Red shifting of the hallmark optic peak occurs due to the anion replacement from P to As. To investigate the electric and thermal conductivities, Seebeck coefficients, and thermopower factor, the Boltzmann transport theory is used to quantify them for these materials. High absorption peaks and figures of merits of these compounds highlight their potential usage in optoelectronics and thermoelectric systems. [ABSTRACT FROM AUTHOR]

Using density-functional theory calculations, we determined the pressure domain of stability of beryllium metasilicate, BeSiO 3 , an elusive compound for which no stable polymorph is known until now. We found that BeSiO 3 is stable at pressures above 9 GPa, a condition that makes it accessible with a large-volume press. After considering the cubic, orthorhombic, and hexagonal perovskite structures and the Ilmenite structure, known from related compounds, we propose that the most stable structure among them is the orthorhombic perovskite structure described by space group Pnma . The unit-cell parameters of this structure are a = 4.966 Å, b = 7.160 Å, and c = 4.374 Å. We also determined the frequencies of Raman and infrared phonons, the elastic constants and modulus, and the electronic band structure for the orthorhombic perovskite structure. Finally, the pressure dependence of unit-cell parameters was calculated. Compression was found to be slightly anisotropic, with the axial compressibilities decreasing following the sequence κ b > κ c > κ a . In addition, we found that BeSiO 3 is quite incompressible with a bulk modulus of 242 GPa, which makes it one of the less compressible silicates. To understand, such a large bulk modulus, both the quantum theory of atoms in molecules and the electron localization function decomposition were utilized to analyze the bonding and to relate it to the mechanical properties.

Finding green energy resources that contribute to the battle against global warming and the pollution of our planet is an urgent challenge. Thermoelectric electricity production is a clean and efficient method of producing energy; consequently, scientists are currently researching and creating thermoelectric materials to increase the efficiency of thermoelectric electricity production and expand the potential of the thermoelectric effect for clean energy production. This work focuses on a comprehensive study of the thermoelectric properties of two-dimensional ScYCBr 2 . We report here a computational analysis of this Janus-like MXene, which is predicted to exhibit outstanding thermoelectric properties. The study uses density-functional theory to provide evidence of the important role played by symmetry breaking to promote low-thermal transport by favoring certain phonon scattering channels. Compared to its symmetric parent compounds, the asymmetric Janus-type ScYCBr 2 displays additional phonon scattering channels reducing the thermal conductivity. An exhaustive investigation of the dynamical stability for both zero-temperature and high-temperature conditions was also performed to support the stability of ScYCBr 2 . Our analysis shows that thanks to its asymmetric structure, the ScYCBr 2 MXene has thermoelectric properties that largely surpass those of its parent symmetric counterpart Sc 2 CBr 2 , being a material with a remarkable thermoelectric high figure of merit. Another advantage of ScYCBr 2 is its high carrier mobility. This work not only demonstrates that this material is a promising thermoelectric material but also shows that ScYCBr 2 can operate efficiently at high temperatures up to 1200 K., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

We report a computational study where we explore the possibility of tuning the electronic properties of orthorhombic methylammonium tin iodide CH 3 NH 3 SnI 3 using strains. According to our findings, a moderate [001] strain, smaller than 2%, would open the band gap up to 1.25 eV and enhance the exciton binding energy, opening up new possibilities for the use of CH 3 NH 3 SnI 3 in technological applications. To better understand the impact of strain, we also examined its influence on bonding properties. The results reveal that the directional pnictogen and the hydrogen bonding are not altered by strains and that the tuning of the electronic properties is the result of changes induced in the orbital contributions to states near the Fermi level and the tilting of the SnI 6 octahedral units., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Identifying and evaluating novel and extremely stable materials for catalysis is one of the major challenges that mankind faces today to rapidly reduce the dependence on fossil fuels. To contribute to achieving this goal, we have evaluated within the density-functional framework the properties of a new two-dimensional MXene structure, the asymmetric MXene YZrCOF monolayer. Phonon dispersion calculations at 0 K and 300 K indicate that the studied material is dynamically stable. The calculations also indicate that the material has a rigid crystal structure with a wide band gap, a strong potential difference, and a band-gap alignment that favors the production of both H 2 and O 2 molecules from water splitting. We also report the outcome of the strain effect on the electrical and photocatalytic characteristics of the studied material. We will demonstrate that even under a large strain, the YZrCOF monolayer is stable and useful for photocatalytic applications.