Ab-initio calculations of physical properties of alkali chloride XCl (X = K, Rb and Li) under pressure

Khalil

et al. 2020

Mater. Res. Express

We have examined structural, electronic and optical properties of TM-GaO 3 (TM=Sc, Ti, Ag) perovskite oxides by means of first Principles study based on density functional theory (DFT). TM represents transition metal elements. To investigate structural properties, exchange correlation potential was determined by employing Full Potential Linearly Augmented Plane Wave (FP-LAPW) technique along with Perdew-Burke-Ernzerhof -GeneralizedGradient Approximation (PBE-GGA) functional. Moreover, Hubbard U eff parameter LDA+U was used to overcome limitations of PBE-GGA functional. All compounds TM-GaO 3 (TM=Sc, Ti, Ag) seem semi-conductor in nature because indirect band gap in each case has been observed with energies 1.33 eV, 0.75 eV and 1.95 eV, respectively. Partial density of states (PDOS) analyses portrayed that 3d orbitals of Sc & Ti, 4d orbital of Ag, and 2p orbital of anions contribute mainly to increase electronic conductivity of the studied compounds. Charge density contour plots depicted ionic nature of TM-cations, while, significant sharing of isolines between O and Ga atoms showed covalent character between them. These contours have also confirmed accumulation of charges around O atoms. Optical analysis revealed that the considered perovskite oxides show sharp increase in optical conductivity and absorptivity in higher energy range when energetic photons are incident upon. Remarkably, they displayed poor reflectivity. However, defect states introduced in the band gap region might be due to cations. These composites are suitable for photovoltaics and other optoelectronic applications OPEN ACCESS RECEIVED

Section: Structural and Electronic Propertiesmentioning

confidence: 99%

Investigations of structural, electronic and optical properties of TM-GaO₃ (TM = Sc, Ti, Ag) perovskite oxides for optoelectronic applications: a first principles study

Khalil

et al. 2020

Mater. Res. Express

“…In general, magnetism in materials occurs due to orientation of the magnetic domains associated with their constituent atoms. Additionally, the electronic band gap energy and density of states are reckoned to be more reasonable to comprehend the crystal structure of any solid material, 36,37 which portrays magnetic behavior of such materials, so these parameters need to be invoked. We have, therefore, presented here spin-polarized band structures, total and projected density of states (PDOSs) along high symmetry paths of the first BZ for considered tantalate perovskite oxides XTaO 3 (X = Rb, Fr).…”

Section: Magnetic and Electronic Propertiesmentioning

confidence: 99%

DFT ‐based insight into the magnetic and thermoelectric characteristics of XTaO ₃ (X = Rb, Fr) ternary perovskite oxides for optoelectronic applications

et al. 2020

Summary Nowadays, there exists an increasing trend of investigating ternary perovskite oxide materials because of their wide applications in solar cells and similar electronic and optoelectronic devices. This work describes a systematic study performed through state‐of‐the‐art ab initio density functional theory (DFT) approach associated with the magnetic, electronic, and thermoelectric behavior of XTaO3 (X = alkali metals i.e., Rb, Fr) tantalate perovskite oxides. These compounds are found to be semiconductor because both materials have shown significant values of the band gap energy, that is, indirect energy band gap of 1.12 eV (↑↓) in RbTaO3 and direct band gap of 1.08 eV (↑↓) in FrTaO3. The calculated formation energies appear to be decreasing such as −3.54 and −1.92 eV for RbTaO3 and FrTaO3, respectively. The analysis through projected density of states discloses that Fr‐6p and 2p states from anion sites have shown overall contribution in forming the highest edge of the valence band (VBM), while, Ta‐5d states have depicted chief role to form major part of the conduction band minima, thereby, contributing in electronic conductivity. The much better values of thermoelectric parameters such as power factor of (5.5062 × 1013 W.m−1.K−2.s−1) and figure of merit (0.82) demonstrate that RbTaO3 is more dominating and promising semiconducting material which would, comparatively, be deemed an appropriate candidate for application in developing efficient thermoelectric devices. Finally, on the bases of above cited facts and the already existing data on similar perovskite oxides, it can be speculated that the studied compounds seem potential candidates to understand underlying physics and for possible applications in thermoelectric and other allied devices.

“…KCl is employed in optical windows for laser applications [8], and as a scintillator or in dosimetry by adding impurities [9][10][11]. At the end of the 1960s, several experimental and theoretical studies on the optical properties of KCl and other AH crystals were presented [12][13][14][15][16][17][18][19]. Recently, theoretical predictions on novel KCl phases under pressure have been proposed [20].…”

Section: Introductionmentioning

confidence: 99%

Cu-Doped KCl Unfolded Band Structure and Optical Properties Studied by DFT Calculations

Castillo-Quevedo¹,

Cabellos²,

Aceves³

et al. 2020

Preprint

The unfolded band structure and optical properties of Cu-doped KCl crystals were computed by first principles within the framework of density functional theory, implemented in the ABINIT electronic structure package utilizing pseudopotential approximation and a plane-wave basis set. From a theoretical point of view, Cu substitution into pristine KCl crystals requires calculation by the supercell (SC) method. This procedure shrinks the Brillouin zone, resulting in a folded band structure that is difficult to interpret. To solve this problem and gain insight into the effect of copper ions (Cu+) on electronic properties, the band structure of SC KCl:Cu was unfolded to make a direct comparison with the band structure of the primitive cell (PC) of pristine KCl. To understand the effect of Cu substitution on optical absorption, we calculated the imaginary part of the dielectric function of KCl:Cu through a sum-over-states formalism and broke it down into different band contributions by partially making an iterated cumulative sum (ICS) of selected valence and conduction bands. Consequently, we identified those interband transitions that give rise to the absorption peaks due to the Cu+ ion. These transitions involve valence and conduction bands formed by the Cu-3d and Cu-4s electronic states