Электронный каталог

Статья

Nematov, D.
Phonopy Calculations of Thermodynamic Properties and Phase Transitions of CsSnI&sub(3) Based on SCAN-Relaxed Structures / D.Nematov, A.Burhonzoda, K.Kholmurodov // Innovation Discovery [Electronic resource]. – 2024. – Vol. 1, No. 2. – P. 17. – URL: https://doi.org/10.53964/id.2024017. – Bibliogr.: 50.

In this work, the structural stability of cubic (α), tetragonal (β), and orthorhombic (γ) phases of perovskite CsSnI&sub(3)3 and their phase transitions have been studied by density functional theory (DFT) calculations, and the results obtained have been compared with the characteristics of nonperovskite orthorhombic (δ) modification of CsSnI&sub(3) compounds. The relaxed structures of the CsSnI3 phases were produced and their geometrical properties were assessed using the strictly constrained normalized potential (SCAN) functional. According to the results, the energetic hierarchy of CsSnI&sub(3) polymorphs is E&sub(β) > E&sub(α) > E&sub(γ) > E&sub(δ). The phonon and thermodynamic characteristics as well as the temperatures of phase transitions of CsSnI&sub(3) have been estimated using the Phonopy tool based on SCAN relaxed structures. The nature of the change in the total energy of the four phases of CsSnI&sub(3) from VASP package calculations justifies the trends of free energy, entropy, enthalpy, and heat capacity. In contrast, the β- phase, which has the highest energy among the perovskite phases, is extremely unstable. It was discovered that the tetragonal phase becomes stable at 450K and transitions to the cubic phase at lowering temperatures. CsSnI&sub(3) undergoes a phase transition between γ- and β-phases at 300-320K. At temperatures below 320K, a black-yellow transformation of CsSnI&sub(3) occurs, in which the black perovskite transforms into a yellow non-perovskite conformation. It was found that temperature phase transitions occur between two orthorhombic phases of CsSnI&sub(3) at 360K, although direct transitions of the α⟷γ and γ⟷δ types have not yet been reported in the literature, with the exception of γ→δ transitions under the influence of moisture.



ОИЯИ = ОИЯИ (JINR)2024
Спец.(статьи,препринты) = С 45 а - Термодинамические величины элементов и соединений
Бюллетени = 6/025