First-Principles Study on Structural, Electronic, Elastic, Phonon, and Thermodynamic Properties of Tungsten Oxide-Based Perovskite NaWO₃

The structural, electronic, elastic, phonon, and thermodynamic properties of the cubic perovskite structure of the NaWO₃ compound were calculated from first-principles studies based on density functional theory (DFT). These properties were computed within localized density approximation (LDA). The lattice constant (a) and bulk modulus (B) for NaWO₃ are found as 3.857 Å, 225.314 GPa, respectively. The band structure displayed that the NaWO₃ compound exhibits metallic behavior at zero pressure. For elastic properties, elastic constants (C_ij), isotropic shear modulus (G), Young’s modulus (Y), Poisson’s ratio (\(v\)), and anisotropy factor (A) were studied. At zero pressure, the calculated C₁₁, C₁₂, and C₄₄ are 558.933, 88.681, and 66.245 GPa, respectively. According to the results, NaWO₃ is mechanically stable. A is not equal to 1. This reveals that NaWO₃ is an anisotropic compound. Because of the Cauchy pressure and B/G ratio, NaWO₃ behaves ductilely. The shear constants (C₁₂ and C₄₄) are less sensitive to pressure than C₁₁ which indicates little resistance to shear deformation. The negative phonon frequencies were observed in phonon dispersion curves. Therefore, NaWO₃ is dynamically unstable. Finally, heat capacity (C_V), entropy (S), and Helmholtz-free energy (F) were also calculated and discussed at 0–1000 K. Consequently, NaWO₃ is a potential candidate for future new device designs.