Lead-strontium borate halides with hilgardite-type structure and their SHG properties
- Department of Materials Science, Moscow State University, Leninskie Gory, Moscow 119991, GSP-1 (Russian Federation)
- Department of Chemistry, Moscow State University, Leninskie Gory, Moscow 119991, GSP-1 (Russian Federation)
- EaStChem, School of Chemistry, St. Andrews University, St. Andrews, KY16 9ST (United Kingdom)
Lead-containing members of the hilgardite family of borate halides, M{sub 2}B{sub 5}O{sub 9}X (M=Ca, Sr, Ba, Pb; X=Cl, Br) exhibit an abnormally large nonlinear optical response. In order to establish any underlying crystal-chemical rationale for this we have carried out detailed crystallographic characterisations of the representative members of this series, Sr{sub 2}B{sub 5}O{sub 9}Cl and Pb{sub 2}B{sub 5}O{sub 9}Cl, using powder neutron diffraction. Both adopt the orthorhombic hilgardite structure type, in space group Pnn2. The full solid solution range Pb{sub 2-x}Sr{sub x}B{sub 5}O{sub 9}Cl has also been prepared, and studied by X-ray Rietveld and second harmonic generation (SHG) measurements. The SHG response shows a linear decrease with increasing x, whereas the unit cell shows an increasing orthorhombic distortion. However, the crystallographic results suggest no significant or systematic changes in the nature of the borate sublattice between Sr{sub 2}B{sub 5}O{sub 9}Cl and Pb{sub 2}B{sub 5}O{sub 9}Cl. We conclude that the enhanced SHG response in Pb-containing hilgardites is due predominantly to the presence of the polarizable nature of Pb{sup 2+}, in particular the presence of a stereochemically active lone pair. - Graphical abstract: Sr{sub 2}B{sub 5}O{sub 9}Cl, Pb{sub 2}B{sub 5}O{sub 9}Cl and the solid solution range Pb{sub 2-x}Sr{sub x}B{sub 5}O{sub 9}Cl has been prepared, and studied by powder neutron and X-ray diffraction and SHG measurements.
- OSTI ID:
- 21128389
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 8; Other Information: DOI: 10.1016/j.jssc.2008.04.018; PII: S0022-4596(08)00207-7; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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