Verneuil growth of TiO2 (rutile) crystals of large size and low dislocation density at low gas flow rate

Rapid Growth of High-Quality Rutile TiO2 Single Crystals through a Laser Floating Zone Method

“…transmittance of the crystal remained at 70% in a transmittance range of 0.41-4.54 which is consistent with the results previously reported [1].…”

“…Figure 7 is the transmission spectrum of the crystal grown in this experiment. The results show that the crystal had no transmittance in the ultraviolet band, and the transmittance of the crystal remained at 70% in a transmittance range of 0.41-4.54 µm, which is consistent with the results previously reported [1].…”

“…Four modes were observed here: B 1g (142 cm −1 ), the multi-phonon peak (236 cm −1 ), E g (447 cm −1 ), and A 1g (610 cm −1 ), and the results were roughly in line with those formerly covered [23,28]. Moreover, B 1g (142 cm −1 ), E g (447 cm −1 ), and A 1g (610 cm −1 ) were in accordance with the rocking vibration, twisting vibration, and axial antisymmetric contraction of the O-Ti-O bonds, respectively [1,23]. The remaining B 2g mode was confirmed to be at 825 cm −1 by Porto et al, although it was not detected in the present spectra [27].…”

“…TiO 2 crystals have widespread applications in optical telecommunications, photocatalysis, photoelectric detection, optical polarizers, and so on [1][2][3]. For example, rutile TiO 2 single crystals can be made into polarizing devices from visible to mid-infrared, owing to their large birefringence (∆n = 0.26) [4], fine chemical resistance [3], and high transmittance in the wide band (0.4-4.5 µm) [1]. Therefore, many types of polarizers made of rutile single crystals are now available in various optical devices [5].…”

“…The growth rate is not easy to control in the conventional Verneuil method [13]. In the latest research, an intelligent control system was introduced and a numerical simulation was used to optimize the growth parameters, to improve crystal quality [1]. However, the etching pit density (EPD) is slightly higher than that of crystals grown using the floating zone method, which is still a problem to be overcome.…”