“… Here, E s (A), E s (Ge), and E s (F) are the energy of A (= K, Rb), Ge, and F atoms, respectively, whereas, E tot (AGeF 3 ) represents the unit cell total energy of AGeF 3 , and N is the number of atoms in the unit cell. The negative values of Δ E f at all applied pressures reveal the thermodynamic stability of titled halide systems 42 . Figure 1 The optimized crystal structure of halide perovskites KGeF 3 and RbGeF 3 .…”
The current study diligently analyzes the physical characteristics of halide perovskites AGeF3 (A = K, Rb) under hydrostatic pressure using density functional theory. The goal of this research is to reduce the electronic band gap of AGeF3 (A = K, Rb) under pressure in order to improve the optical characteristics and assess the compounds’ suitability for optoelectronic applications. The structural parameters exhibit a high degree of precision, which correlates well with previously published work. In addition, the bond length and lattice parameters decrease significantly leading to a stronger interaction between atoms. The bonding between K(Rb)–F and Ge–F reveal ionic and covalent nature, respectively, and the bonds become stronger under pressure. The application of hydrostatic pressure demonstrates remarkable changes in the optical absorption and conductivity. The band gap becomes lower with the increment of pressure, resulting in better conductivity. The optical functions also predict that the studied materials might be used in a variety of optoelectronic devices operating in the visible and ultraviolet spectrum. Interestingly, the compounds become more suitable to be used in optoelectronic applications under pressure. Moreover, the external pressure has profound dominance on the mechanical behavior of the titled perovskites, which make them more ductile and anisotropic.
“… Here, E s (A), E s (Ge), and E s (F) are the energy of A (= K, Rb), Ge, and F atoms, respectively, whereas, E tot (AGeF 3 ) represents the unit cell total energy of AGeF 3 , and N is the number of atoms in the unit cell. The negative values of Δ E f at all applied pressures reveal the thermodynamic stability of titled halide systems 42 . Figure 1 The optimized crystal structure of halide perovskites KGeF 3 and RbGeF 3 .…”
The current study diligently analyzes the physical characteristics of halide perovskites AGeF3 (A = K, Rb) under hydrostatic pressure using density functional theory. The goal of this research is to reduce the electronic band gap of AGeF3 (A = K, Rb) under pressure in order to improve the optical characteristics and assess the compounds’ suitability for optoelectronic applications. The structural parameters exhibit a high degree of precision, which correlates well with previously published work. In addition, the bond length and lattice parameters decrease significantly leading to a stronger interaction between atoms. The bonding between K(Rb)–F and Ge–F reveal ionic and covalent nature, respectively, and the bonds become stronger under pressure. The application of hydrostatic pressure demonstrates remarkable changes in the optical absorption and conductivity. The band gap becomes lower with the increment of pressure, resulting in better conductivity. The optical functions also predict that the studied materials might be used in a variety of optoelectronic devices operating in the visible and ultraviolet spectrum. Interestingly, the compounds become more suitable to be used in optoelectronic applications under pressure. Moreover, the external pressure has profound dominance on the mechanical behavior of the titled perovskites, which make them more ductile and anisotropic.
“…In addition to the vacancy formation energy, we further investigate the dynamical stability of the perfect α‐Ga 2 O 3 , O vacancy and Ga vacancy. Generally speaking, the dynamical stability of a solid is estimated by phonon dispersion 48‐51 . No imaginary phonon frequency indicates the dynamical stability of a solid.…”
The Ga 2 O 3 is a promising semiconductor, which is used in electric vehicles and 5G. However, the role of point defect of α-Ga 2 O 3 is unknown. To solve the problem, here, the influence of vacancy on the electronic and optical properties of α-Ga 2 O 3 is studied by the first-principles calculations. Two typical vacancies, O vacancy and Ga vacancy, were designed. The calculated resultsshow that the α-Ga 2 O 3 prefers to form O vacancy in comparison to the Ga vacancy. Furthermore, the calculated band gap of α-Ga 2 O 3 is 2.970 eV. However, the calculated band gap of O vacancy and Ga vacancy is 3.556 and 3.201 eV, which is bigger than the perfect α-Ga 2 O 3 . Essentially, the wide band gap is that the removed atom results in a band shift from the Fermi level to the high-energy regions. The change of band gap of these oxides is affirmed by the dielectric function. Finally, it is found that the α-Ga 2 O 3 oxide shows ultraviolet properties, which are in good agreement with the Ping and Berhanuddin's result. However, the calculated optical adsorption coefficient shows that the O vacancy induces the movement from the ultraviolet region to the visible light. The O vacancy and Ga vacancy weaken the storage optical properties of α-Ga 2 O 3 based on the analysis of loss function functional.
K E Y W O R D Sα-Ga 2 O 3 , electronic properties, first-principles calculations, optical properties, vacancy
“…The stability of the predicted phase is estimated from the first‐principles calculation at the electronic level 34‐38 . Here, the first‐principles based on the density functional theory were calculated in the CESTEP code 39 .…”
Section: Model and Methodsmentioning
confidence: 99%
“…The stability of the predicted phase is estimated from the first-principles calculation at the electronic level. [34][35][36][37][38] Here, the first-principles based on the density functional theory were calculated in the CESTEP code. 39 The Perdew-Burke-Ernzerhof functional of AlH 3 hydrides in the framework of all electron projector augmented was used.…”
Summary
AlH3 hydride is a typical hydrogen storage material due to the high storage, low density and low temperature decomposition temperature, but the structural feature of AlH3 remains controversial. In addition, the optical properties of AlH3 are unclear. In this work, the first‐principles method is used to study the structural, optical and electronic properties of AlH3 hydride. Two possible AlH3 hydrides, viz. rhombohedral and cubic structures are considered. The stability of the rhombohedral AlH3 is demonstrated based on the analysis of phonon dispersion. Moreover, the band gap of rhombohedral and cubic AlH3 is 2.170 and 0.656 eV, respectively. Naturally, the semiconductor feature of AlH3 is related to the band separation of H‐s state and Al‐3p state. The dielectric functional diagram demonstrates the semiconductor properties of AlH3 hydride. Furthermore, it is found that the AlH3 shows the ultraviolet response.
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