Study of elastic, structural, thermoelectric and optoelectronics characteristics of Na₂YCuX₆(X = Br, Cl) halide double perovskites

Abstract

The structural, electronic, optical, elastic, and thermoelectric (TE) characteristics of Na2YCuX6 (X=Br, Cl) halide double-perovskites were investigated by using first principle approach within WIEN2K code. Perdew, Burke and Ernzerhof generalized-gradient approximation (PBEsol-GGA) with modified Becke-Johnson (mBJ) potential were used in the investigations. Enthalpy of formation energies determined for Na2YCuBr6 and Na2YCuCl6 were -2.29 eV and -1.955 eV, correspondingly which verify the stability of both compounds. It is found that Na2YCuCl6 has a semiconducting nature with direct bandgap (Eg) of 2.571 eV and Na2YCuBr6 has for indirect Eg of 2.492 eV. Absorption coefficient shows largest values at 5.74 and 6.92 eV for Na2YCuBr6 and Na2YCuCl6 , correspondingly, which lie in UV range. Pugh’s ratio (B/G) values were calculated as 2.00 and 4.62 for Na2YCuCl6 and Na2YCuBr6 , respectively which confirm the ductile nature and ionic bond in the compounds. From the thermoelectric calculations, ZT shows maximum values of 0.74 and 0.73 for Na2YCuBr6and Na2YCuCl6, respectively. Results showed that investigated compounds are efficient candidates for optical and TE applications.

First-Principles Calculations to Investigate Direct-Band Novel Cobalt-Based Double Perovskite Materials for Optoelectronic Applications

“…Shear modulus G is much larger than B and the decisive modulus of elasticity affecting the mechanical stability . Moreover, ductility and brittleness can be differentiated by the Pugh’s ratios ( B / G ) and Poisson’s ratio. , The critical values are 1.75 and 0.26, respectively, which means ductile materials of the Pugh’s ratios are larger than 1.75 or Poisson’s ratio are larger than 0.26, and are otherwise brittle materials. Based on the results, the F-based materials are ductile and promising candidates in flexible devices.…”

Investigation of structural, electro-magnetic and optical properties of cubic SmXO3 (X=Fe, Mn, Cr) perovskites

“…The σ (ω) gives information about the bonds breaking in the compound due to striking light. As σ(ω) reveals the generation of unbound carriers upon the absorption of incoming light, there exists an inseparable connection between σ(ω) and absorption [42,43]. The highest peaks of σ (ω) are obtained with magnitude of 5560 (Ω cm) -1 (at 7.81 eV) for SmCrO 3 , 5623 (Ω cm) -1 (at 7.52 eV) for SmMnO 3 and 4963 (Ω cm) −1 (at 7.53 eV) for SmFeO 3 (see figure 5(b)).…”