DFT Study of Structural, Electronic, Optical and Elastic Properties of the YxB1–xP Ternary Alloy

The current paper provides a first principle study about the structural, electronic, optical and elastic properties of the ternary alloys \({{{\text{Y}}}_{x}}{{{\text{B}}}_{{1 - x}}}{\text{P}}\) using the full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT) with the Wu–Cohen generalized gradient approximation (WC–GGA) and the modified Becke–Johnson potential (mBJ) approach in the structure zinc blend or NaCl. The lattice parameter versus yttrium Y concentration was calculated and was examined by Vegard’s law. Next, we applied the mBJ method to calculate electronic properties, accordingly we found that BP and \({{{\text{Y}}}_{{0.25}}}{{{\text{B}}}_{{0.75}}}{\text{P}}\) exhibit an indirect band gap, while the alloys \({{{\text{Y}}}_{{0.5}}}{{{\text{B}}}_{{0.5}}}{\text{P}}\), \({{{\text{Y}}}_{{0.75}}}{{{\text{B}}}_{{0.25}}}{\text{P}}\) and the compound YP behave like metals. A transition from semiconductor to metal occurs when the yttrium concentration exceeds 50%. According to our calculated optical spectra, a significant reflection in both visible and ultraviolet domains is noticed, allowing for a promising application in optoelectronics. The elastic constants are obtained using the methodology of Charpin. We found that the alloy \({{{\text{Y}}}_{{0.5}}}{{{\text{B}}}_{{0.5}}}{\text{P}}\) is brittle. In contrast, the other ternary alloys and the two binary compounds BP and YP are ductile. Furthermore, for the binary compounds BP and YP, our calculations indicate that the lattice parameter a, Bulk modulus B, energy gap \({{E}_{g}}\), dielectric function \({{{{\varepsilon }}}_{1}}\left( 0 \right)\) and \(n\left( 0 \right)\) refractive index, the elastic constants \({{C}_{{11}}}\), \({{C}_{{12}}}\), and \({{C}_{{44}}}\), the shear constant Cs, the shear modulus G, the anisotropy factor A, the Poisson’s ratio ν, the Young’s modulus Y, and the Kleinman parameter ζ, are close to the experimental and theoretical data.