Characterization of unidirectionally grown NaCl1−xBrxO3 crystals

Abstract

NaCl1−xBrxO3 single crystals were prepared by unidirectional crystallization. The influences of the composition on structure, quality, and optical properties of NaCl1−xBrxO3 crystals were investigated. X-ray powder diffraction analysis revealed that the diffraction patterns for the NaCl1−xBrxO3 crystals have almost the same set of peaks as those of NaClO3 and NaBrO3, except that an extra very weak forbidden (100) diffraction peak was detected at about 13.3° 2θ for crystals grown from solutions of BrO3−∼15–70 at. % (i.e., x=0.15–0.70). These crystals can, therefore, be considered to have a distorted cubic structure closely related to the cubic structures of NaClO3 (x=0) and NaBrO3 (x=1). Our study also found that good-quality crystals can only be obtained in two doping ranges (x>0.75 or x<0.10). Outside these two ranges, the crystals tended to crack and even became opaque. Lattice distortions in the crystals were the probable cause as revealed by X-ray powder diffraction patterns. The optical activity of NaCl1−xBrxO3 crystals measured by a laser was found to decrease from 2.89 to 2.01°/mm with increasing value of x from 0 to 0.02. Stimulated Raman scattering of NaBr0.90Cl0.10O3 crystals was measured using a 0.532-μm ps laser as a pump source and four anti-Stokes lines plus six Stokes lines were observed. The fourth anti-Stokes emission was found to be at 454.5 nm and the sixth Stokes emission at 713.6 nm. Its Raman gain coefficient was determined to be 18.4 cm/Gw.