Growth of lithium triborate crystals. II. Experimental results

doi:10.1016/0022-0248(95)00462-9

Journal of Crystal Growth

Volume 158, Issue 4, 1 February 1996, Pages 523-533

https://doi.org/10.1016/0022-0248(95)00462-9 Get rights and content

Abstract

In Part I [C. Parfeniuk, I.V. Samarasekera and F. Weinberg, J. Crystal Growth 158 (1996) 514], a mathematical model of the flux growth of lithium triborate (LBO) crystals was used to calculate the temperature distribution and fluid flow in the melt during growth. In this report the model results are related to experimental observations. Temperature measurements in the melt, for different crucible rotation rates, are compared to the corresponding temperatures determined from the model. Direct observations of fluid flow in the melt, using a transparent glycerol/water solution as a physical model, are related to the calculated flow paths and velocities. As the LBO crystal grows, the rejected MoO₃ flux concentrates ahead of the interface leading to the formation of eutectic phases. The factors leading to the formation of these phases are examined, using flow velocity values determined from the model. A number of LBO crystals were grown, first using convenient growth parameters, and then using parameters determined from the model results. The size and quality of the crystals obtained are discussed and related to the growth conditions.

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In 2010, Kokh et al obtained over 1.3 kg large-sized LBO crystals using the method of heat-field symmetry control [11]. In 2011, several large LBO crystals were grown with the weight of 2 kg level [10,17]. In the present work, in order to obtain large aperture LBO element for OPCPA, after many trials, growth along [1 0 0] direction has successfully been used to modify crystal morphology and enhance crystal yield for OPCPA schemes.
LBO crystal up to 192 × 130 × 89 mm³ in size and 2327 g in weight has been grown by TSSG method and cut into an optical element with a size of 100 mm × 100 mm × 17 mm for critically phase-matched type I (θ = 90°, Ø = 13.85°). Near phase-matching direction growth was introduced to promote yield of the final large aperture LBO elements greatly from the limited mass of crystal. Take into consideration of crystallographic symmetry, the linear thermal expansion coefficients and crystal growth habit, LBO grown along [1 0 0] direction was proved to be the best choice to produce large element which meet the demands of high power OPCPA schemes. The grown LBO crystal possesses high optical quality, and shows no evidence that crystal growth modifications have detrimental influence on the crystal property. The laser-induced damage threshold (LIDT) at λ = 1064 nm and τ = 5 ns is 42 J/cm² for 1-on-1 type tests. Absorption at 1064 nm has been found to be 10–20 ppm/cm at 1064 nm). Especially, the optical homogeneity reached 1.9 × 10⁻⁷ cm⁻¹ in full aperture for the optical elements mentioned above, to the best of our knowledge, the highest optical homogeneity in borate crystals. This extremely high optical homogeneity, large aperture optical element of LBO is more favorable in the high power laser schemes.
Czochralski and Flux Growth of Crystals for Lasers and Nonlinear Optics
2015, Handbook of Crystal Growth: Bulk Crystal Growth: Second Edition
In this chapter, the Czochralski and flux growth of laser and nonlinear optical crystals is reviewed, including Ho-, Tm-, and co-doped Gd₃Ga₅O₁₂; the vanadate family; and a series of important borate crystals. The growth conditions and basic properties of these crystals are summarized. In vanadate family growth, the relationship of spiral growth to crystal seed orientation was determined. In the case of flux growth, growth conditions for barium metaborate, lithium triborate, cesium triborate, cesium lithium triborate, potassium beryllium borate fluoride, bismuth triborate, and related crystals were collected. Among these, many high-quality crystals are widely used and represent a good reference model for researchers into crystal growth.
Large LBO crystal growth at 2 kg-level
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All these are benefits for the growth of a large LBO crystal. Although MoO3 flux could reduce the viscosity of LBO–MoO3 system [10,11], the viscosity of Li2O–B2O3–MoO3 system has not been measured. The crystallization region in this system was determined by Pylneva et al. [12], but this region was too broad for crystal growth.
The growth of large size and high quality LBO crystal is always the research hotspot in nonlinear optical crystal field. In order to obtain large size LBO crystal, it is very important to explore a suitable region in a good flux system. The suitable region for LBO crystal growth in the Li₂O–B₂O₃–MoO₃ ternary system was investigated by the viscosity measurement. LBO crystal, up to 160×150×77 mm³ in size and 1988 g in weight, was successfully grown by seeding in [011] direction. The LBO single crystal processed was of high quality. Optical homogeneity reached 3.8×10⁻⁶ cm⁻¹, transmittance was more than 90% from 200 nm to 380 nm and the laser-induced surface damage threshold was 11.2 GW/cm² (λ=1064 nm, τ=7.5 ns).
Topology of liquidus surface in B<inf>2</inf>O<inf>3</inf>-Li<inf>2</inf>O·B<inf>2</inf> O<inf>3</inf>-Li<inf>2</inf>O·MoO<inf>3</inf>-MoO<inf>3</inf> system: Implications to the growth of lithium triborate single crystals
2001, Materials Research Bulletin
The paper presents the literature-based review of phase diagrams for the B₂O₃-Li₂O, B₂O₃-MoO_3, LiO₂-MoO₃ binary systems and B₂O₃-Li₂O-MoO₃ ternary system and the results of the experimental studying the polythermal sections of Li₂O·B₂O₃ - Li₂O·MoO_3, Li₂O·3B₂O₃ - MoO₃ and Li₂O·3B₂O₃ - 2Li₂O·5MoO₃ systems. The section of Li₂O·B₂O₃ - Li₂O·MoO₃ was confirmed to be quasi-binary: it divides the ternary phase diagram into two subsystem diagrams, which can be investigated independently. Basing on original and published data the topological analysis of liquidus surface in the B₂O₃ - Li₂O·B₂O₃ - Li₂O·MoO₃ subsystem –which is of special interest for the growth of lithium triborate (LBO) single crystals –was performed. Due to the lack of information several topologies of the surface may be provided which accord well with the available experimental data. It was shown that to choose a correct version of topology one could use the data on the subsolidus triangulation of the compositional tetragon of the subsystem under investigation. The relevant experiment was carried out and the triangulation scheme was determined through the phase composition of one sample. The topological scheme of liquidus surface and the subsolidus triangulation scheme in the compositional tetragon of the B₂O₃ - Li₂O·B₂O₃ - Li₂O·MoO₃ - MoO₃ subsystem were plotted. We succeeded to define the region of LBO primary crystallization on the phase diagram and to grow optically good-quality LBO single crystals.
Effect of NaCl melt-additive on the growth and morphology of LiB<inf>3</inf>O<inf>5</inf> (LBO) crystals
2001, Journal of Crystal Growth
The growth of nonlinear optical crystals of large size and excellent quality is of prime importance for frequency conversion applications. In the flux growth of LiB₃O₅ (LBO), the presence of extended BO₃ and BO₄ chain-like structures gives rise to highly viscous melts. As a consequence, mass transport is restricted and the depletion of material at the melt–crystal interface results in unstable hopper growth. The addition of small amounts of NaCl to the melt is effective in breaking BO₄ bond chains. The resulting reduction in viscosity facilitates an increase in growth rate by up to a factor of 3. However, the incorporation of NaCl into the lattice may have an adverse effect on crystal quality. In the present study, LBO crystals of typical dimension 30×30×26 mm³ were grown by top-seeded solution from borate fluxes doped with 2 and 4 mol% NaCl, and without NaCl. Changes in growth and morphology are described as a function of melt dopant concentration. Laser damage threshold will be discussed in relation to the concentration of NaCl in the crystal.
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1999, Journal of Crystal Growth
The Li₂O–B₂O₃–MoO₃ ternary system was investigated to determine the region of growth of lithium triborate Li₂O·3B₂O₃ (LBO) crystals with good optical properties. The top-seeded solution growth method, the method of spontaneous crystallisation and solid-state reactions were used in this investigation. The phases were defined by the method of X-ray power diffraction. The data obtained in these experiments made it possible to choose the region of compositions of solutions in the Li₂O–B₂O₃–MoO₃ system for the successful growth of LBO single crystals. LBO single crystals, up to 100×82×45 mm³ in size and 290 g in weight, were grown free of cracks, bubbles and inclusions. These single crystals were of high optical quality: wavefront distortion (fringe per mm for λ=0.633 μm) was lower than $1150$ , absorption losses (0.25 μm<λ<2.5 μm) in the resultant LBO single crystals were lower than 0.005 cm⁻¹, and the damage threshold at λ=1.06 μm, τ=10 ns in the LBO single crystals was more than 10.0 GW/cm². High performance non-linear optical elements of various optical orientations, up to 20×20×20 mm³ in size, were fabricated on our LBO crystals.

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Electronic materialGrowth of lithium triborate crystals. II. Experimental results

Abstract

J. Crystal Growth

J. Crystal Growth

Chim. Ital.

J. Am. Ceram. Soc.

J. Crystal Growth

Z. Anorg. Allg. Chem.

Yogo-Kvokai-Shi

Electronic material
Growth of lithium triborate crystals. II. Experimental results