A new phase of dibarium copper disilicate, b-Ba2CuSi2O7, was obtained by the solid-state reaction. Crystal data: Mr = 506.4, tetragonal, P421m, a = 8.284(2), c = 5.313(3) ? V = 364.6(4) ?, Z = 2, Dc = 4.61 g/cm3, l(Mo...A new phase of dibarium copper disilicate, b-Ba2CuSi2O7, was obtained by the solid-state reaction. Crystal data: Mr = 506.4, tetragonal, P421m, a = 8.284(2), c = 5.313(3) ? V = 364.6(4) ?, Z = 2, Dc = 4.61 g/cm3, l(MoKa) = 0.71703 ? ?= 13.91 mm-1, F(000) = 450 and T = 293(2) K; the final R = 0.0343, wR = 0.0382 and S = 1.02 for 512 observed reflections (I > 3s(I)) refined by 34 variables. The compound was characterized by a layered structure composed of CuO4 tetrahedra and Si2O7 anions with the Ba cations filling the cavities between the layers. The building blocks of the present structure are similar to those in the a-Ba2CuSi2O7, but the linkage of CuO4 tetrahedra and Si2O7 anions is significantly different. In particular, the double-tetrahedral anions of Si2O76- form an orthogonal arrangement in the present structure, in contrast to the parallel arrangement reported in the a-Ba2CuSi2O7.展开更多
The microscopic defects have been investigated for crystal Tm3+/Yb3+:YVO4. These defects mainly include the inclusions (solid inclusions, bubbles and inclusions of the liquid phase), dendrites and growth stripes. They...The microscopic defects have been investigated for crystal Tm3+/Yb3+:YVO4. These defects mainly include the inclusions (solid inclusions, bubbles and inclusions of the liquid phase), dendrites and growth stripes. They are caused by in-pure raw materials, unstable growth conditions, super-cooling component and so on. Tm3+/Yb3+:YVO4 crystals of large size and excellent optical quality are grown by improving the growth conditions to eliminate these defects.展开更多
基金the Innovative Project (No.IP01007) and Hundred-Talent Program (No. 990168) of the Chinese Academy of Sciences
文摘A new phase of dibarium copper disilicate, b-Ba2CuSi2O7, was obtained by the solid-state reaction. Crystal data: Mr = 506.4, tetragonal, P421m, a = 8.284(2), c = 5.313(3) ? V = 364.6(4) ?, Z = 2, Dc = 4.61 g/cm3, l(MoKa) = 0.71703 ? ?= 13.91 mm-1, F(000) = 450 and T = 293(2) K; the final R = 0.0343, wR = 0.0382 and S = 1.02 for 512 observed reflections (I > 3s(I)) refined by 34 variables. The compound was characterized by a layered structure composed of CuO4 tetrahedra and Si2O7 anions with the Ba cations filling the cavities between the layers. The building blocks of the present structure are similar to those in the a-Ba2CuSi2O7, but the linkage of CuO4 tetrahedra and Si2O7 anions is significantly different. In particular, the double-tetrahedral anions of Si2O76- form an orthogonal arrangement in the present structure, in contrast to the parallel arrangement reported in the a-Ba2CuSi2O7.
基金The work was supported by the National Natura1 Science Foundation of China(5997203)
文摘The microscopic defects have been investigated for crystal Tm3+/Yb3+:YVO4. These defects mainly include the inclusions (solid inclusions, bubbles and inclusions of the liquid phase), dendrites and growth stripes. They are caused by in-pure raw materials, unstable growth conditions, super-cooling component and so on. Tm3+/Yb3+:YVO4 crystals of large size and excellent optical quality are grown by improving the growth conditions to eliminate these defects.
