The Hydrothermal Growth Of CaB₈O₁₁(OH)₄ & BSO Crystals And Their Properties

NLO crystal CaB8O11(OH)4 can be used in all-solid-state lasers. Bi12SiO20(BSO) is widely used in optical signal processing and information storage. This dissertation is comprised of two sections:1. Investigation on the hydrothermal growth of CaB8O11(OH)4 crystal and its properties. (1) Analytical grade H3BO3 and CaO were used as the starting materials. Pure water which was 45% the mass of H3BO3 and CaO were put into the autoclave. The temperature was raised to 280℃~350℃by a computer program. After 5 days, millimeter-size colorless CaB8O11(OH)4 crystal was obtained; (2) Structural aspects were discussed. The layered B-O skeleton in CaB8O11(OH)4 is composed of [B3tBB3ΔO10(OH)]3 - and [B2ΔO(OH)3]+ . The directions of BΔO3 groups in [B3tB3BΔO10(OH)]3- and [B2ΔO(OH)3]+ are almost the same, which causes the strong SHG effect; (3) Its properties were investigated by TG-DSC, FT-IR, SHG and UV-Vis-NIR. The SHG output of CaBB8O11(OH)4 crystals equals to 1~2 times that of KDP grains in similar size. Transmission is maintained below 200nm and the transmittance is up to 80% between 350nm~750nm.2. Investigation on the hydrothermal growth of BSO crystal and its properties. BSO glass was prepared by quenching method. BSO crystals formed by spontaneous nucleation were used as the starting material for hydrothermal growth. An aqueous solution of 5mol/L sodium hydroxide was used as the mineralizer and the filling degree was about 60%~70%. The temperature was raised to 380℃by a computer program and a typical growth period was 15 days. Cracked BSO was obtained when 1wt% and 2wt% SiO2 was added into the growth system, while good-quality BSO was obtained when SiO2 was 4.8wt%.