Composition Dependent Structural, Electronic, Mechanical and Optical Properties of Sr₃P_l-_xAs_xCl₃ using DFT Calculations

The work illustrates structural, mechanical and optoelectronic properties of Sr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</inf>-<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Cb using Density Functional Theory (DFT) calculation by CASTEP software. GGA-PBE has been selected as the functional. To investigate the resulting changes in mechanical, electrical, and optical properties as a function of the Arsenic addition percentage, the initial investigation on Sr3PCb involved converting its unit cell into a supercell structure and doping it with varying concentrations of Arsenic (As). When Arsenic (As) was added in place of Phosphorus (P), significant variations were observed in those properties. Phonon dispersion, formation energy and elastic constant evaluation, conducted according to the Born Stability Criteria, indicate that Sr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</inf>-<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Cb perovskites remain mechanically and thermally stable up to the As concentration of 30%. In order to assess the material's ductility or brittleness, we calculated the mechanical properties of the material using the elastic constant. Band gap decreases when As is substituted in Sr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</inf>-<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Cb from 0% to 30%. The band gap varied while the level of arsenic increased. We have calculated that Sr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</inf>-<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Cb has a direct band gap structure that extends from the valence band maximum point to the conduction band minimum point. We also studied optical characteristics like reflection and absorption. Arsenic is added, the study finds that the reflectivity and absorption coefficient of Sr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</inf>-<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Cb both rise noticeably, from 0% to 30%.