A new modification of Ba[B5O8(OH)] center dot H2O, the refined structure of Ba-2[B5O9]Cl center dot 0.5H(2)O, and the role of the pentaborate structural units in the formation of the quadratic optical nonlinearity

作者：Belokoneva E L^*; Stefanovich S Yu; Erillov M A; Dimitrova O V; Mochenova N N

来源：Crystallography Reports, 2008, 53(2): 228-236.

DOI：10.1134/S1063774508020107

The structure of a new modification of the barium pentaborate beta-Ba[B5O8(OH)] center dot H2O synthesized under hydrothermal conditions is investigated. This structure differs from the previously studied structure of the alpha-Ba[B5O8(OH)] center dot H2O compound by a shorter interlayer spacing and a higher degree of filling of the intersheet space with water molecules and barium atoms (the space group P (1) over bar is retained). The structure of the Ba-2[B5O9]Cl center dot 0.5H(2)O pentaborate from the family of orthorhombic hilgardites (space group Pnn2) is refined, and the property of this crystal to generate the second optical harmonic is revealed. It is found that the previously studied pentaborate Ba-5[B20O33(OH)(4)]H2O exhibits a nonlinear optical activity. The relationship between the structure and properties of hydrous and anhydrous pentaborates is discussed.

• 出版日期2008-4