First-principle investigations of structural, electronic, thermal, and mechanical properties of AlP1-xBix alloys

CONTEXT

In this work, a comprehensive study concerning the physical properties of ternary alloys system (AlP_1-xBi_x) at different concentrations is presented. The obtained results from our first-principle calculations are compared with previously reported studies in the literature and discussed in detail. Our computed results are found in a nice agreement where available with earlier reported results. Electronic band structures at the above-mentioned concentrations are also determined. Likewise, the impact of the varying temperature and pressure on Debye temperature, heat capacity, and entropy is analyzed as well. Furthermore, elastic constants and related elastic moduli results are also computed. Our results show that alloys are stable and found to be in brittle nature. This is the first quantitative study related to ternary alloys (AlP_1-xBi_x) at mentioned concentrations. We soon expect the experimental confirmation of our predictions.

METHOD

The calculations are performed, at concentrations x=0.0, 0.25, 0.5, 0.75, and 1.0 by using the "full potential (FP) linearized (L) augmented plane wave plus local orbital (APW+lo) method framed within density functional theory (DFT)" as recognized in the "WIEN2k computational code". The "quasi-harmonic Debye model" approach is employed to determine the thermal properties of the title alloys.

Electronic structure and optical properties of the dialkali metal monotelluride compounds: Ab initio study

Structural parameters, electronic structure and optical properties of the dialkali metal monotelluride M₂Te (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure were investigated via ab initio calculations using the all electron linearized augmented plane wave approach based on density functional theory with and without including spin-orbit coupling (SOC). The exchange-correlation interactions were described within the PBEsol version of the generalized gradient approximation and Tran-Blaha modified Becke-Johnson potential (TB-mBJ). Optimized equilibrium lattice parameters are in excellent accordance with existing measured ones. Computed energy band dispersions show that the studied compounds are large band gap materials. Inclusion of SOC reduces the band gap value compared to the corresponding one calculated without including SOC. Determination of the energy band character and interatomic bonding nature are performed using the densities of states diagrams and charge density distribution map. Linear optical function spectra are predicted for a wide energy range and the origin of the dielectric function spectrum peaks are determined.

The influence of strain on the polarization of epitaxial (Ba(0.70)Sr(0.30))TiO(3) ultrathin film obtained from first principles

A first-principles-derived approach is used to investigate the temperature-versus-misfit strain phase diagram of (Ba(0.70)Sr(0.30))TiO(3) ultrathin film. Our predicted phase diagram is qualitatively similar to those developed by Shirokov et al (2009 Phys. Rev. B 79 144118) and Ban and Alpay (2002 J. Appl. Phys. 91 9288). However, there are some quantitative differences that are microscopically revealed and explained. The results also indicate that the electrical polarization is very sensitive to the applied strain. Moreover, the polarization components show a strong dependence on the surface/interface, thickness, and electrical boundary conditions.