Optical Floating Zone Growth of β-BaB₂O₄ from a LiBa₂B₅O₁₀-Based Solvent

Abstract

Low-temperature barium metaborate β-BaB2O4 has been grown using a LiBa2B5O10-based solvent in a four-mirror optical floating zone furnace with a traveling solvent zone configuration. The β-BaB2O4 rods grown are composed of several different crystal domains, ranging from 100 μm to 1 mm in diameter, and lithium, a component of the flux, was present only at the contaminant level. The technique demonstrates that thermal decomposition of the incongruently melting phase LiBa2B5O10 can be used to grow β-BaB2O4.

Borates: A Rich Source for Optical Materials

“…For this purpose, large size and optically perfect β-BaB 2 O 4 crystals are in great demand and thus many techniques have been proposed over the past 35 years. Several techniques have been used in order to optimize the crystal growth process of β-BaB 2 O 4 crystal, including Czochralski, top-seeded solution, laser-heated pedestal, optical floating zone, traveling solvent-zone melting, and immersion-seeded solution crystal growth technique. − Among them, the top-seeded solution growth method is more appropriate, in particular, for the growth of large size β-BaB 2 O 4 crystals without inclusions. Most of above method should involve suitable flux system, and thus there are a number of fluxes that have been applied with different advantages for the growth of β-BaB 2 O 4 crystals up to now. − For example, monocomponential B 2 O 3 , Li 2 O, Na 2 O, NaF, and BaF 2 as well as dicomponential Na 2 O-NaF and Na 2 O-B 2 O 3 are the most common fluxes used for growing β-BaB 2 O 4 crystals.…”

“…Poeppelmeier et al . demonstrated that the thermal decomposition of the incongruently melting phase LiBa 2 B 5 O 10 can be used to grow β-BaB 2 O 4 crystals with different scales in 2007 . By 2019, Simonova et al .…”

Phase equilibria in the ternary reciprocal system Li, Ba // BO2, F and growth of bulk β-BaB2O4 crystals

“…The BaB 2 O 4 , BaF 2 , LiF and LiBO 2 compounds melt congruently at 1100, 1353, 848 and 843 C, respectively. The eutectic coordinates of the BaB 2 O 4 -(LiBO 2 ) 2 e 1 system are 25 mol% BaB 2 O 4 and 75 mol% (LiBO 2 ) 2 , 777 C (Pan et al, 2007); (LiBO 2 ) 2 -(LiF) 2 e 2 -59 mol% LiBO 2 and 41 mol% LiF, 725 C (Petit & Jaeger, 1957); (LiF) 2 -BaF 2 e 3 -72 mol% LiF and 28 mol% BaF 2 , 760 C (Berezhnaya & Bukhalova, 1957); BaB 2 O 4 -BaF 2 e 4 -41 mol% BaB 2 O 4 and 59 mol% BaF 2 , 760 C (Bekker et al, 2011).…”

Viewpoint: Inorganic Materials for UV and Deep-UV Nonlinear-Optical Applications

“…With respect to size, a minimum of 5 mm in all three dimensions is necessary, and with respect to high quality, a rocking curve measurement around a Bragg reflection should generate a peak with a full-width at half-maximum (fwhm) of less than 100 arcseconds (0.0278°), ideally less than 50 arcseconds (0.0139°). There are a myriad of ways to grow crystals including top-seeded solution growth, Czochralski, Bridgman, and floating zone. − As such, no one method is suitable for all materials. In addition to growing the crystal, the crystal must be cut, indexed, and polished to measure its linear-optical and NLO properties.…”