Lattice engineering of LiNb1-xTaxO₃ solid solutions: Comprehensive exploration of the structural, electronic, optical, piezoelectric, and mechanical properties

In order to explore the variations of structural properties and physical properties of the solid solutions of lithium niobate and lithium tantalate (LNT, LiNb 1-x Ta x O 3 ), LiNb 1-x Ta x O 3 ( x = 0, 0.083, 0.167, 0.25, 0.333, 0.417, 0.5, 0.583, 0.667, 0.75, 0.833, 0.917, 1) crystal structures with different Nb/Ta ratios were constructed. A combined approach of experimental research and first-principles calculations was employed. The structural and physical properties of LNT single crystals were computationally analyzed using the DS-PAW software. The geometric structure and electronic structure were analyzed by the calculated lattice constant, band structure, and state density (DOS); the piezoelectric coefficient e 33 and elastic constant C ij of the LNT system were calculated, and the mechanical parameters such as Young's modulus (Y), bulk modulus (B), shear modulus (G), and Poisson's ratio ( ν ) were obtained from C ij to analyze the effects of tantalum content on piezoelectric and mechanical properties; the optical performance indexes of the LNT system, such as the real part ε 1 and the imaginary part ε 2 of the dielectric function, absorption coefficient α, extinction coefficient k(ω), reflectance R(ω), refractive index n(ω), optical conductivity σ, and energy loss L(ω), were calculated to study its optical properties. Through calculation and analysis in this paper, a database of basic physical properties of LNT single crystals with different Nb/Ta ratios has been constructed to guide the research on the properties of LNT related devices.