Crystal growth,structure and properties of bismuth triborate BiB3O6 crystal

BiB3O6 (BIBO) single crystals with size of 46 × 23 × 10 mm3 and weight of 26.0 g have been successfully grown by top-seeded method.Problems encountered in the growth process of this crystal have been discussed in detail,and the methods of growing high-quality large crystals have been put forward.The relationship between their structure and properties is studied.The space group of monoclinic BiB3O6 is C2 and 03(7),b=4.9948(7),c=6.5077(7),the cell parameters are a=7.1293(5)3.The density of BIBO is 4.8965 g/cm3.β=105.586(8)″,and V=222. The Mohs's scale of hardness is 5.5-6.There is no cleavage face in the crystal.The transmittance of BIBO is about 80 percent in the range from visible coherent light to near-infrared light.The ultraviolet cutoff wavelength is at 276 nm.BiB3O6 is a biaxial crystal and has two sets of axes,and the relative orientation of (X,Y,Z) with regard to (a,b,c) is: X//b,(Y,c)=47.2°,(Z,a)=31.6°,determined by X-ray analysis combined with polarized microscopy.Second-harmonic-generation (SHG) experiments were carried out for the first time.In type I phase-matching (PM) directions (11.1°,90°) and (168.9°,90°),SHG conversion efficiencies of two directions for 1.064 μm light are up to 67.7 % and 58%,respectively.We have also obtained the third-harmonic-generation (THG) of 1.064 μm.The comparative experiments between BIBO and KTP were carried out on conversion efficiency,transmittance and hardness.All the above results indicate that BiB3O6 is a kind of excellent nonlinear optical (NLO) crystal.