Method for growing large-sized rare-earth-doped barium yttrium fluoride single crystals

Abstract

The invention provides a method for growing large-sized rare-earth-doped barium yttrium fluoride single crystals. The method comprises the following steps: in a heating furnace, putting polycrystals of {xReF3+(1-x)YF3} and BaF2 into a crucible according to a mass ratio, vacuumizing, and introducing argon gas into the heating furnace successively, wherein the mass ratio of {xReF3+(1-x)YF3} to BaF2 is 2 to 1 and x is 0-100%; controlling the heating power by a temperature control instrument to melt the polycrystals, performing heat exchange by flowing of a liquid surface in the crucible and the gas in the furnace to form an axial temperature difference, and forming a radial temperature difference of temperature on a wall of the crucible and temperature in the center of the crucible to cause natural convection of a melt; fixing BaY2F8 seed crystals to a seed crystal rod by a platinum chuck, and lowering the seed crystals to be contacted with the melt for fluoride crystal growth; when fluoride crystals grow to have set sizes, annealing, cooling to the room temperature at a speed of 20 DEG C / hour, adjusting the rotary speed and the heating power, separating the crystals from the melt until the crystal growth is ended, and annealing in the crucible to obtain the large-sized fluoride crystals. The method solves the problems of negative growth factors of difficulty for crystal growth, a large amount of air bubbles in the crystals and the like caused by poor flowability of the fluoride melt.

Description

technical field [0001] The invention belongs to the field of crystal growth, in particular to a rare earth-doped yttrium barium fluoride Re:BaY 2 f 8 Crystal, especially a large-size fluoride single crystal growth method with a single crystal size greater than 50mm. Background technique [0002] In recent years, rare earth-doped upconversion and laser materials have attracted great attention due to their broad application prospects in laser, optical display, atmospheric monitoring, laser remote sensing, imaging, laser medical treatment, and lidar. Rare earth doped yttrium barium fluoride crystal (Re:BaY 2 f 8 , Re: BYF) belongs to the monoclinic crystal system, biaxial crystal. The crystal has low phonon energy (maximum phonon energy 415cm －1 ), the spectral transmission range is wide (0.12-12 μm), and the grown crystal has direct output of mid-infrared band laser and high conversion efficiency. It is widely used in infrared solid-state lasers and detection fields. A ...

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Problems solved by technology

However, the disadvantage of this method is that the entire growth process cannot be observed, real-time adjustment cannot be made during the growth process, and the growth cycle is long, requiring harsh growth conditions.

[0005] The temperature gradient method can avoid the complex convection and temperature fluctuation of the solid-liquid interface caused by the interference of the irregular mechanical vibration source, so the quality of the grown crystal and the single crystal rate are better than the crucible drop method, but due to the crystal growth process Completely relying on diffusion transport, the crystal growth is relatively slow, and there is no relative movement between the growing crystal and the temperature field, which limits the height of the crystal; the traditional top seed crystal method grows during the seed crystal rotation and does not pull upward, and the growth cycle is long. At the same time, this method uses a fully enclosed crucible, the entire growth process is invisible, and the heating method uses graphite heating. The crucible is generally a graphite crucible, and graphite volatilization will affect the quality of the grown crystal.

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