A Cubic Non-Centrosymmetric Mixed-Valence Iron Borophosphate-Phosphite
A first member of a new family of metal borophosphate-phosphite Fe1.834 IIFe0.166 IIIB0.5[PO3(OH)]0.8(HPO3)2.033 has been successfully synthesized by using the boric acid-phosphorous acid flux. The compound crystallizes in the cubic crystal system in a non-centrosymmetric space group I4¯3d (No. 220) with unit cell parameters of a = 21.261(3) Å, and Z = 48, featuring a very condensed network of FeO6 octahedra and disordered phosphate-phosphite moieties with mixed valency of iron. The compound contains a novel fundamental building unit (FBU), a cyclic borophosphate-phosphite ring which is further connected to form a propeller like partial anionic structure. Metal polyhedra also form a propeller-like structure through edge-sharing and are further connected to the partial anionic structure to form the three-dimensional structure. Thermal analyses, infrared and Mössbauer spectroscopy, magnetic and second harmonic generating (SHG) measurements using 1064 nm radiation have been performed on this compound. SHG measurements indicate that the compound has an efficiency approximately equal to α-SiO2.
H. Yaghoobnejad Asl et al., "A Cubic Non-Centrosymmetric Mixed-Valence Iron Borophosphate-Phosphite," Crystal Growth and Design, vol. 16, no. 3, pp. 1187-1194, American Chemical Society (ACS), Jan 2016.
The definitive version is available at http://dx.doi.org/10.1021/acs.cgd.5b01106
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