Study of New Infrared Non-Linear Optical Crystal BaGa4Se7 Based on First Principle

Xie Huang,Rong Dai,Junfeng Yan,Fuchun Zhang,Jing Ning,Lei Zhang

doi:10.3390/cryst12020143

Abstract

The electronic structure and optical properties of BaGa4Se7 crystals were studied by generalized gradient approximation (GGA) and Heyd–Scuseria–Ernzerhof (HSE). The electronic structure results showed that BaGa4Se7 is a nonlinear optical crystal with a direct wide band gap. The band gap was calculated to be 2.36 eV using the HSE06 method, which is basically equal to the experimental value. The band structure showed that the top of the valence band was largely contributed by Ga 4s, 4p and Se 4p states, while the bottom of the conduction band was mainly comprised of Ga 4s, 4p, Se 4p, and Ba 5d states. The optical properties showed strong absorption and reflection in the ultraviolet region and strong transmittance in the infrared region. The average static refractive index of BaGa4Se7 was 2.73, and the static birefractive index was 0.04. These values indicate that the material has a good phase-matching ability and a wide laser damage threshold. The above results indicate that BaGa4Se7 is a potential infrared nonlinear optical crystal material.

Highlights

Chalcogenides compounds have become the main research and application materials in the field of nonlinear infrared crystal materials due to their large nonlinear optical coefficients, suitable birefringence and sufficiently high laser damage thresholds [1,2,3,4].the characteristics of metal sulfide in the material’s light absorption and the construction of high nonlinear optical effect units make it a new type of mid-to-far infrared nonlinear optical material [5].BaGa4 S7 and BaGa4 Se7 show great second-harmonic generation (SHG) effect in chalcogenides when detected in laser pump, which is about 2–3 times that of the benchmark material AgGaS2 [6]
BaGa4 Se7 lattice constants were a = 7.739 Å, b = 6.635 Å, c = 14.936 Å, α = γ = 90, β = 121.048, and the BaGa4 Se7 crystal belongs to the orthorhombic crystal system, while the experimentally achieved results were a = 7.625 Å, b = 6.511 Å, c = 14.702 Å, α = γ = 90, β = 121.240, and the relative error was not more than 0.019
We used PBE, HSE06, HSE03 B3LYP, and PBE0 methods to analyzing the results of the four methods, the band gap values calculated by the HSE06 electronic and optical

Summary

Introduction

Chalcogenides compounds have become the main research and application materials in the field of nonlinear infrared crystal materials due to their large nonlinear optical coefficients, suitable birefringence and sufficiently high laser damage thresholds [1,2,3,4]. BaGa4 S7 and BaGa4 Se7 show great second-harmonic generation (SHG) effect in chalcogenides when detected in laser pump, which is about 2–3 times that of the benchmark material AgGaS2 [6]. This has attracted the wide attention of researchers. Yelisseyev [12] and others subsequently grew a large BaGa4 Se7 crystal, and used crystal optics and spectroscopy to study its optical properties, proving the possibility of controlling the luminescence parameters by annealing after growth in a Academic Editors: Yuri Kivshar and

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