Predictions on structural, electronic, optical and thermal properties of lithium niobate via first-principle computations

ABSTRACT

In this work, we present our predictions on lithium niobate LiNbO₃ concerning its structural, electronics, thermal and optical properties. These predictions are done by means of first-principles calculations performed within the full potential linearised augmented plane wave plus local orbital (APW + lo) approach designed within the density functional theory (DFT). The generalised gradient approximation (GGA), to appraise the electron exchange–correlation, parameterised by Perdew–Burke and Ernzerhof is implemented. From our calculations, optimised results for lattice parameters are obtained by optimising the volume of the simulated hexagonal unit cell of lithium niobate. Our computed results for structural parameters are consistent with the data reported in the literature. On the other hand, for the better description of the band structure/energy band gap, calculations of the band structure are performed, as well, at the level of GGA-mBJ with and without the inclusion of spin–orbit coupling effect. Our calculations of electronic band structure and density of states (DOS) show that LiNbO₃ is a direct and wide bandgap material as the transition is found to be along (Γ-Γ) symmetry direction with numerical value about 4.084 eV. However, no significant influence of the spin–orbit coupling (SOC) is noted on the band gap energy. Furthermore, optical parameters like dielectric function, anisotropy, refractive index, birefringence, extinction and absorption coefficients, optical conductivity and the energy loss spectrum (EELS) have also been calculated for an energy range, 0–40 eV. Similarly, by employing the ‘Debye Quasi-Harmonic Model’ crucial thermal parameters of the LiNbO₃ are predicted.

KEYWORDS:

• Hexagonal crystal structure
• FP-LAPW
• electronic band structure
• optical
• and thermal parameters

PACS:

• 71.22.+i
• 71.15.Ap
• 65.40.-b
• 71.15.Nc
• 74.25.Gz
• 71.15.Mb
• 71.20.Nr

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author S. Bin Omran acknowledges the financial support of Research Supporting Project number (RSP-2019-82), at King Saud University, Riyadh, Saudi Arabia.