P-006

Miglė Minalgaitė1

migle.minalgaite@chgf.stud.vu.lt

Skirmantė Tutlienė2, Martynas Misevičius1,2, Ramūnas Skaudžius1

1Department of Inorganic Chemistry, Vilnius University, Lithuania.

2Department of Chemical Engineering and Technology, Center for Physical Sciences and Technology (FTMC), Vilnius, Lithuania

Lithium fluoride single crystal growth using the Czochralski method

According to the definition, a single crystal is a solid object in which an ordered three-dimensional arrangement of atoms, ions or molecules is repeated throughout the entire volume. Single crystals represent a pivotal component within technological applications, with utilisation spanning domains such as optoelectronics, laser technology [1] and X-ray detection [2], amongst numerous others. The Czochralski method was a major breakthrough in the field of crystal growing, enabling the production of crystals of unparalleled quality[3].

Lithium fluoride (LiF) is an inorganic compound that crystallises in a face-centred cubic structure described by the space group Fm3 ̅m. The lattice parameters of the LiF crystal are a = b = c = 4.027 Å [4].

LiF crystals are an essential material for advanced optical systems, including lasers [5], X-ray optics, spectroscopy equipment and ultraviolet (VUV) components. These crystals exhibit a broad transmittance range (0.120 - 7 μm) [6] making them indispensable in high-precision optical instruments.

The objective of this study is to gain insight into the Czochralski method. This is a process that is used to produce single crystals from a melt. The material is melted in a crucible, after which the seed crystal is immersed in the melt, slowly rotated and extracted. The melt that is pulled with the crystal seed crystallises on its surface, and the crystal continues to grow. In addition to the capabilities of the existing equipment, the process of LiF single crystal growth is discussed.

References:

[1] J. Yan et al., “Advances in the Synthesis of Halide Perovskite Single Crystals for Optoelectronic Applications,” Chemistry of Materials, vol. 35, no. 7, pp. 2683–2712, Apr. 2023, doi: 10.1021/ACS.CHEMMATER.2C03505.

[2] D. Liu et al., “Universal growth of perovskite thin monocrystals from high solute flux for sensitive self-driven X-ray detection,” Nature Communications 2024 15:1, vol. 15, no. 1, pp. 1–10, Mar. 2024, doi: 10.1038/s41467-024-46712-y.

[3] C. D. Brandle, “Czochralski growth of oxides,” J Cryst Growth, vol. 264, no. 4, pp. 593–604, Mar. 2004, doi: 10.1016/J.JCRYSGRO.2003.12.044.

[4] L. Mei, X. Cai, D. Jiang, J. Chen, W. Guo, and W. Xiong, “Investigation of thermal neutron scattering data for BeF2 and LiF crystals,” J Nucl Sci Technol, vol. 50, no. 4, pp. 419–424, Apr. 2013, doi: 10.1080/00223131.2013.773169/ASSET/8D3B0DBB-8E83-4FD8-A7CF-8777FA07C174/ASSETS/IMAGES/TNST_A_773169_O_F0006G.JPG.

[5] G. Baldacchini, “Colored LiF: an optical material for all seasons,” J Lumin, vol. 100, no. 1–4, pp. 333–343, Dec. 2002, doi: 10.1016/S0022-2313(02)00460-X.

[6] M. A. Vincenti, “Advanced spectroscopic investigation of color centers in LiF crystals exposed to 6 MV X-ray clinical beams”, doi: 10.1393/ncc/i2017-17093-6.