Research On The Synthesis, Growth And Properties Of New Ultraviolet And Deep-ultraviolet Nonlinear Optical Crystal Materials, K₃B₆O₁₀Cl And Ba₄B₁₁O₂₀F

Two new halogen complex borates, K₃B₆O₁₀Cl (KBOC) and Ba₄B₁₁O₂₀F (BBOF)have been found in the K₂O-KCl-B₂O₃and BaO-BaF₂-B₂O₃systems. The large singlecrystals have been grown by the top-seeded solution growth method and some propertieshave been characterized. In addition, other four novel borates and two organic-inorganichybrid borates have been synthesized by the high-temperature solution method and theslow evaporation of water solution at room temperature, respectively. The dissertationmainly consists of the discussions about their solid-state synthesis, crystal structuredetermination, crystal growth and measurement of properties.1. Research on UV nonlinear optical KBOC crystalPure phase of KBOC compound was synthesized by the solid-state reaction for thefirst time. The crystal structure of KBOC was determined by the single crystal X-raydiffraction. KBOC crystallizes in the rhombohedral system, space group R3m with unit-cellparameters a=10.0624(14), c=8.8361(18), Z=4, V=774.8(2)3. The structureexhibits an intricate3-dimensional (3D) network composed of [B₆O₁₀] units and [ClK₆]octahedra and can also be described as two networks (a [B₆O₁₀]∞and a ReO₃-type ClK₆network) that are interweaved.As-prepared KBOC has a powder second harmonic generation (SHG) effect aboutthree times that of KDP and is phase matchable as supported by powder SHGmeasurements. The large SHG response arises from the distortions of [B₆O₁₀] and ClK₆groups.The TG-DSC analysis proves that KBOC is an incongruently melting compound. Ahigh quality single crystal of KBOC with dimensions up to25mm×11mm×7mm wassuccessfully grown by the top-seeded solution growth method for the first time. By theminimum deviation technique, the refractive indices of the crystal were measured andfitted to the Sellmeier equations. The limit of type-I phase matching SHG wavelength wascalculated to be255nm. The transmittance spectrum shows that the as-grown crystal is transparent in the wavelength range of180-3460nm. The thermal properties and laserdamage threshold have been investigated. The two principal coefficients of thermalexpansion along a and c axes were measured to be3.08×10^-6and28.4×10^-6K^-1,respectively. The optical damage threshold was estimated, which is more than9.2GW/cm².The measured hardness of the KBOC crystal is approximately4-5Mohs.Experiments demonstrate that the KBOC crystal is nonhygroscopic, very stable in water orair.2. Research on UV nonlinear optical BBOF crystalPure phase of BBOF was synthesized by the solid-state reaction for the first time. Thecrystal structure of BBOF was investigated. It crystallizes in the orthorhombic system,space group Cmc21with unit-cell parameters a=18.8112(15), b=10.7151(6), c=8.6031(5), Z=4, V=1734.1(2)3. BBOF has a3D network structure, in which a newFunction Building Block (FBB) B11O24was observed. The FBBs are connected with eachother by sharing O atoms to form3D network with tunnels viewing along c axis, whereBa(1)-F(1)-Ba(2) chains are filled, and the Ba(3) atoms are located at symmetrical site inthe periphery of the tunnel.The SHG measurement suggests that BBOF has a powder SHG effect about10timesthat of KDP and is phase matchable.The TG-DSC experiment proves that BBOF melts incongruently. BBOF single crystalhas been grown by the high temperature solution method. The UV-vis-NIR transmittancespectrum of the BBOF crystal was measured, and the UV cutoff edge is about190nm. Themeasured hardness of the BBOF crystal is approximately5Mohs.3. Research on four new borate compoundsFour compounds, K₃ZnB₅O₁₀, Pb_xBa_9-xB₁₈O₃₆, K₃B₃O₃F₆and CsB₅O₈, have beenfound to crystallize in new structure types. Some properties of the compounds are reported.The DSC experiments prove that K₃ZnB₅O₁₀melts congruently. In Pb_xBa_9-xB₁₈O₃₆, the FBB is B₃O₆group. By comparing the structures of Pb_xBa_9-xB₁₈O₃₆with that of β-BaB₂O₄,it is found that the arrangement of B₃O₆groups in the compounds leads to different SHGeffect. In K₃B₃O₃F₆, the FBB is B₃O₃F₆, but scarcely see the linkage of B-F under ambientpressure. CsB₅O₈crystallizes in the orthorhombic space group Pccn. By comparing thestructures of CsB₅O₈with that of α-CsB₅O₈, β-CsB₅O₈andγ-CsB₅O₈, it is found that thedifference of FBB among the compounds leads to crystallize in different space groups.4. Research on two organic-inorganic hybrid borate compoundsSr[B(C₆H₅O₇)₂](H₂O)₄3H₂O and Ca[B(C₆H₆O₇)₂](H₂O)₄HCl have been synthesizedby the slow evaporation of water solution at room temperature. Their crystal structureswere established by single-crystal X-ray diffraction and optical properties were measured.