Ab initiocalculations of the structural, electronic, thermodynamic and thermal properties of BaSe_1−xTe_xalloys

Abstract

The alkaline earth metal chalcogenides are being intensively investigated because of their advanced technological applications, for example in photoluminescent devices. In this study, the structural, electronic, thermodynamic and thermal properties of the BaSe1−xTex alloys at alloying composition x = 0, 0.25, 0.50, 0.75 and 1 are investigated. The full potential linearized augmented plane wave plus local orbital method designed within the density functional theory was used to perform the total energy calculations. In this research work the effect of the composition on the results of the parameters and bulk modulus as well as on the band gap energy is analyzed. From our results, we found a deviation of the obtained results for the lattice constants from Vegard’s law as well as a deviation of the value of the bulk modulus from the linear concentration dependence. We also carried out a microscopic analysis of the origin of the band gap energy bowing parameter. Furthermore, the thermodynamic stability of the considered alloys was explored through the measurement of the miscibility critical temperature. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the BaSe1−xTex alloys, and these investigations comprise our first theoretical predictions concerning the BaSe1−xTex alloys.

Theoretical investigation of electronic performance, half-metallicity, and magnetic properties of Cr-substituted BaTe

“…The agreement is very good between our computed E X for BaTe and calculations [37,38] using the same GGA-WC and TB-mBJ approaches. Also, our result for E X with TB-mBJ is better than other calculations [39,40] using the GGA-PBE [42] and LDA [43] approximations. Note that the calculated E X , G HMF , and G HM gaps obtained with TB-mBJ are higher than obtained with the GGA-WC, because the TB-mBJ semilocal exchange correlation potential can provide perfect bandgaps compared with the LDA and different versions of the GGA approxima- a direct half-metallic ferromagnetic (HMF) gap and halfmetallic (HM) gap.…”

“…We chose the average of the muffin-tin radii of Ba, Te, and Cr atoms in such a way that the muffin-tin spheres do not overlap. Besides, the charge density was Fourier results of these parameters are better than recent calculations [39,40] using the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) [42] and local density approximation (LDA) with Teter-Pade parameterization [43]. This is due to the precise GGA-WC exchange potential for structural properties.…”

“…Structural parameters of BaTe and Ba 1−x Cr x Te at various concentrations were determined by fitting the variation of the total energy as a function of volume using the Murnaghan equation [36]. The structural parameters such as the lattice constant (a), bulk modulus (B), and its pressure derivative (B ) calculated for BaTe and Ba 1−x Cr x Te at different concentrations using the GGA-WC approximation, together with other theoretical [37][38][39][40] and experimental data [41], are summarized in Table 1. The a and B parameters obtained for BaTe are in good agreement with experimental [41] and recent theoretical calculations [37,38] using the GGA-WC approximation [31].…”

“…The minorityspin bands of Ba 1−x Cr x Te reveal two types of bandgap, viz. tions, using the GGA-WC and TB-mBJ exchange potentials, together with other theoretical [37][38][39][40] and experimental [48,49] data, are presented in Table 2. The agreement is very good between our computed E X for BaTe and calculations [37,38] using the same GGA-WC and TB-mBJ approaches.…”

Extreme pressure conditions of bas based materials: Detailed study of structural changes, band gap engineering, elastic constants and mechanical properties

“…In the recent years, barium chalcogenides based materials have attracted great scientific and industrial interest due to their potential technological applications e.g. in microelectronics and magneto-optical devices [1][2][3][4][5][6][7][8][9][10]. Furthermore, due to their strong ionic character and metallization behaviour under high pressures [11,12] these compounds are promising candidates for various electrical and optical devices in the future [13,14].…”