A new nonlinear optical (NLO) material, BiTeBO (BTBO), is successfully grown from high temperature solution method. BTBO crystallizes in a polar space group of P6 with a framework structure composed of [BiO] blocks, with TeO and BO interconnection. It is interesting that in the BTBO structure three types of NLO-active units, including stereochemically active lone pair cations (Bi cations), second-order Jahn-Teller distorted octahedra (TeO octahedra) and π-orbital planar groups (BO groups), simultaneously exist. The additive contribution from these three types of groups results in an extremely large second harmonic generation (SHG) response in BTBO (about 20 times that of KDP), exhibiting the largest SHG effect among the known borate NLO materials. The enhancement of the nonlinear optical property is elucidated by the first-principles analysis.

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Single crystals of the birefringent material Ba 2 Ca(B 3 O 6 ) 2 (BCBO) with dimensions up to 40 × 28 × 10 mm 3 were successfully grown by top-seeded solution growth (TSSG) method from B 2 O 3 −NaF flux. It exhibits high transmittance in the range of 190−3000 nm with UV cutoff of 178 nm, which is much shorter than that (189 nm) of the commercial UV birefringent crystal, the high-temperature phase of BaB 2 O 4 (α-BBO). Meanwhile, BCBO crystal has large birefringence (Δn = n o − n e = 0.2524−0.0862) in the wavelength range from 178 to 3000 nm and without phase transition from room temperature to the melting point. A prototype of Glan−Taylor polarizer made from BCBO crystal showed an optical extinction ratio of 10 4 :1, which is comparable to those of commercial birefringence crystals. The experimental results demonstrate that the BCBO crystal can be a new promising birefringent crystal for UV, especially the sub-200 nm deep-UV range.

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D eep-ultraviolet (DUV) coherent light sources (λ < 200 nm), which are always rare resources, have attracted much attention because of the significant role played in semiconductor photolithography, high density storage, laser micromachining, material processing, photochemical synthesis and scientific equipment. 1−4 As is well accepted, the most efficient way to produce practical DUV laser is using solid-state lasers with nonlinear optical (NLO) crystal through cascaded second-harmonic generation (SHG) conversion. Hence, an appropriate DUV NLO crystal that can produce SHG below 200 nm is the key to generating high quality DUV lasers.According to the anionic group theory proposed by Chen, 5−8 a good DUV NLO crystal should possess the following three optical properties: (1) wide transparent range in the UV region with the UV cutoff wavelength far below 200 nm; (2) a moderate birefringence (Δn ∼ 0.08) to ensure the phasematching ability; (3) a sufficient second-order nonlinear coefficient. Specifically, the first two conditions are indispensable for a DUV NLO material. Taking the famous LiB 3 O 5 (LBO) crystal as an example, 9 the transmittance spectrum is wide and the UV absorption edge is down to about 155 nm.

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The two new metal cyanurates Ba2M­(C3N3O3)2 (M = Sr, Pb) were successfully grown by a solid-state cyclotrimerization reaction. The electronic energy bands of Ba2M­(C3N3O3)2 are totally divergent in spite of their same structures and similar interlayer distances. Theoretical calculations show the narrowing band gap of Ba2Pb­(C3N3O3)2 stems from the strong interaction between Pb 6p orbitals and anti-π orbitals in (C3N3O3)3– groups.