Control of Melt Composition and Purity for Growth of LiTbF₄ Crystals by the Bridgman Method with a Pt Crucible Sealing Technique

High-quality LiTbF₄ crystals were successfully grown for the first time using the Bridgman method with a platinum (Pt) crucible vacuum-sealed technique. Using the laser sealing technique, the raw materials were sealed directly in a Pt crucible under high-vacuum conditions to control the composition and purity of the melt. A single-crystal rod with dimensions of Φ12 mm × 80 mm was grown using this method, and several samples were prepared to characterize the optical properties. The as-grown crystal exhibited a narrow full width at half-maximum (fwhm) of 0.038° on the (112) plane, low absorption coefficients (<0.005 cm^-1 at 1064 nm), and high transmittance in the 400-1500 nm wavelength range. The results indicated that the Bridgman method with the Pt crucible laser-sealed technique is an effective way for growing high-quality LiTbF₄ crystals, and is expected to be applied for growing other fluoride crystals.