Structure Design and Crystal Growth of UV Nonlinear Borate Materials. In: Wu X, Chen L, editors. Structure-Property Relationships in Non-Linear Optical Crystals I. Berlin: Springer Berlin Heidelberg; 2012. pp. 181-221. [DOI: 10.1007/430_2011_69]

Incongruent Melting La xY ySc4-x-y(BO3)4: LYSB Nonlinear Optical Crystal Grown by the Czochralski Method

Nonlinear optical (NLO) crystals with incongruent melting of La _xY _ySc _z(BO₃)₄ ( x + y + z = 4) (LYSB)-type were grown for the first time, to the best of our knowledge, by the Czochralski method. A special thermal assembly was used and the melt composition, growth direction, and the pulling and rotation rates have been optimized. Good optical quality LYSB crystal with a diameter of about 13 mm and a length of 25 mm has been grown from the La_0.765Y_0.485Sc_2.75(BO₃)₄ starting melt composition, along the c-axis direction, using a slow rotation rate of 8-10 rpm and a high pulling rate of 2 mm/h. The grown crystal has an acentric huntite-type structure (space group R32, Z = 3) with cell dimensions a = 9.8098(4) Å and c = 7.9802(3) Å, and its chemical composition was determined to be La_0.78Y_0.32Sc_2.90(BO₃)₄. The optical transmission and the refractive indices were determined, and the second harmonic generation (SHG) and sum frequency generation (SFG, ω + 2ω) properties were reported. The laser damage threshold was also determined to be ∼2.0 GW/cm² at 1064 nm (6 ns pulses). The main nonlinear properties of Czochralski-grown LYSB crystal were found to be similar to those of flux-grown LYSB, and comparable to YAl₃(BO₃)₄ (YAB) nonlinear properties. The big advantage of Czochralski-grown LYSB crystals is that they can be grown with large size and high quality, making them promising candidates for various NLO applications, including frequency conversion of high-average power radiation sources.

Structural Design of Two Fluorine-Beryllium Borates BaMBe2(BO3)2F2 (M = Mg, Ca) Containing Flexible Two-Dimensional [Be3B3O6F3]∞ Single Layers without Structural Instability Problems

Molecular structural design is a compelling strategy to develop new compounds and optimize the crystal structure by atomic-scale manipulation. Herein, two fluorine-beryllium borates, BaMgBe₂(BO₃)₂F₂ and BaCaBe₂(BO₃)₂F₂, have been rationally designed to overcome the structural instability problems of Sr₂Be₂B₂O₇ (SBBO). When relatively large Ba atoms were introduced, the [Be₆B₆O₁₅]_∞ double layers of SBBO were successfully broken, generating flexible [Be₃B₃O₆F₃]_∞ single layers. Also, the strategy adopted in this work has many implications in understanding the structural chemistry and designing novel optical functional materials in a beryllium borate system.

KB(PO4)F: a novel acentric deep-ultraviolet material

A rational design using the [PO₄] group to replace the [BeO₄] group in KBBF results in a new acentric deep-UV material KB(PO₄)F, free of beryllium.