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Crystal Growth, Characterization, and Properties of Nonlinear Optical Crystals of Li 0.5 Ag 0.5 GaTe 2 for Mid-Infrared Applications.

Authors :
Tang G
He Y
Liao H
Zhang S
Chu X
Si R
Jin Z
Du Y
Wang C
Chen B
He Z
Huang W
Source :
ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2024 Nov 02. Date of Electronic Publication: 2024 Nov 02.
Publication Year :
2024
Publisher :
Ahead of Print

Abstract

LiGaTe <subscript>2</subscript> is a promising nonlinear optical crystal with a large figure of merit ( d <subscript>36</subscript> <superscript>2</superscript> / n <superscript>3</superscript> ), but it is difficult to grow the LiGaTe <subscript>2</subscript> single crystal due to its extreme instability. In this work, we used Ag to replace Li and successfully grew a Li <subscript>0.5</subscript> Ag <subscript>0.5</subscript> GaTe <subscript>2</subscript> crystal by the modified Bridgman method for the first time. We found it has thermal stability below 200 °C in an atmospheric environment, and the thermal expansion coefficient is positive. This is different from LiGaTe <subscript>2</subscript> and AgGaTe <subscript>2</subscript> which have a negative thermal expansion coefficient along the c -axis. When the temperature exceeds 200 °C, Li <subscript>0.5</subscript> Ag <subscript>0.5</subscript> GaTe <subscript>2</subscript> is easily decomposed and oxidized. Under closed vacuum conditions, the melting and solidifying points of Li <subscript>0.5</subscript> Ag <subscript>0.5</subscript> GaTe <subscript>2</subscript> are measured to be 719 and 694 °C. XPS spectra show that the binding energies of Li, Ga, and Te are higher than LiGaTe <subscript>2</subscript> , and the surface is easily oxidized. The A1 vibration modes are found at 117.72 and 135.44 cm <superscript>-1</superscript> by the Raman spectrum which is related to the Te and Ga-Te bond in [GaTe <subscript>4</subscript> ] <superscript>5-</superscript> tetrahedra. Li <subscript>0.5</subscript> Ag <subscript>0.5</subscript> GaTe <subscript>2</subscript> has a wide transmittance range from 0.94 to 20 μm, and there was two-photon absorption near 16 μm. The phonon spectrum and PDOS were simulated by the DFT calculation to study the phonon vibration modes in the lattice, which shows that the density of the Raman vibration is higher than those of AgGaTe <subscript>2</subscript> and LiGaTe <subscript>2</subscript> . The SHG test results showed that the SHG response intensity of Li <subscript>0.5</subscript> Ag <subscript>0.5</subscript> GaTe <subscript>2</subscript> is 1.5 times that of AgGaS <subscript>2</subscript> , which shows its excellent nonlinear optical properties for mid-IR applications.

Details

Language :
English
ISSN :
1944-8252
Database :
MEDLINE
Journal :
ACS applied materials & interfaces
Publication Type :
Academic Journal
Accession number :
39487779
Full Text :
https://doi.org/10.1021/acsami.4c14743