论文部分内容阅读
非线性光学晶体Ca2 B6O11·H2 O(或者 2CaO·3B2 O3 ·H2 O) ,Ca[B3 O5 (OH) ]的阴离子基团为(B3 O8) 7-。虽然 (B3 O8) 7-基团的 2级极化率小于 (B3 O6) 3 -和 (B3 O7) 5 -,但其结构中 ,每个(B3 O8) 7-基团的排列方位一致 ,有利于微观 2级极化率的叠加 ,并且其单位体积内含阴离子基团 (B3 O8) 7-的个数达到 0 .97× 1 0 -2 个 / 1 0 -3 nm3 ,其值是BBO ,LBO的 1 .5倍左右 ,因而仍具有较大倍频效应。该化合物中的阴离子基团 [B3 O7(OH) ]6-含有一个 (OH)基 ,(OH)基取代氧原子不仅对晶体的非线性系数影响不大 ,而且使 (B3 O8) 7-上的 4个终端氧原子分别与硼原子和氢原子相连 ,致使阴离子基团中无“孤氧”存在 ,即 (OH)基取代氧原子反而有利于晶体吸收边的紫移。在CaO B2 O3 H2 O水热体系中存在着如下反应 :3H3 BO3 [B3 O3 (OH) 4]-+H++ 2H2 O ( 1 )[B3 O3 (OH) 4]+H2 O [B3 O3 (OH) 5 ]2 -+H+( 2 )n[B3 O3 (OH) 5 ]2 -[B3 O4(OH) 3 ]n2n-+nH2 O ( 3)[B3 O4(OH) 3 ]2n-n [B3 O5 (OH) ]2n-n +nH2 O ( 4)方程 ( 3) ( 4)受温度控制和硼酸的浓度控制 ,方程 ( 1 ) ( 2 )还要受到pH值的影响。当体系中存在着CO2 时 ,由于CO2 与H2 O的作用气液两相中pH值均降低 ,在降低 [B3 O3 (OH) 5 ]2 -形成速度的同时 ,增加?
The anionic group of the nonlinear optical crystals Ca2B6O11.H2O (or 2CaO.3B2O3.H2O), Ca [B3O5 (OH)] is (B3O8) 7-. Although the (B3 O8) 7- group has a 2-level polarizability less than (B3 O6) 3 - and (B3 O7) 5 -, the orientation of each (B3 O8) 7- group in the structure is uniform, Which is conducive to the superposition of the microscopic 2-level polarizations, and the number of anionic groups (B3 O8) 7- in the unit volume reaches 0 .97 × 10 -2 / 1 0 -3 nm 3, and the value is BBO , LBO 1.5 times, so it still has a larger frequency-doubling effect. The anionic group [B3O7 (OH)] 6- in this compound contains an (OH) group. The substitution of (OH) for oxygen atoms not only has little effect on the nonlinearity of the crystals, Of the four terminal oxygen atoms are connected to the boron atom and the hydrogen atom, respectively, resulting in no “isolated oxygen” in the anionic group. That is to say, instead of the oxygen atom, the (OH) group favors violet absorption along the crystal side. The following reaction exists in the CaO B2 O3 H 2 O hydrothermal system: H 3 BO 3 [B 3 O 3 (OH) 4] - + H ++ 2H 2 O (1) [B3O3 (OH) 4] 5] 2 - + H + (2) n [B3O3 (OH) 5] 2- [B3O4 (OH) 3] n2n- + nH2O (3) [B3O4 (OH) 3] 2n-n [B3O5 (OH)] 2n-n + nH2O (4) Equation (3) (4) Under temperature control and boric acid concentration control, equation (1) and (2) are also affected by the pH. When CO2 is present in the system, the pH value of both gas and liquid phases decreases due to the action of CO2 and H2 O, and the rate of formation of [B3 O3 (OH) 5] 2 increases at the same time.