Influence of the cation size on the framework structures and space group centricities in AMo2O5(SeO3)2 (A = Sr, Pb, and Ba).
ABSTRACT Two new quaternary mixed-metal selenites, SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2), have been synthesized as crystals and pure polycrystalline phases by standard solid-state reactions using SrMoO(4), PbO, MoO(3), and SeO(2) as reagents. The crystal structures of the reported materials have been determined by single-crystal X-ray diffraction. SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2) are isostructural and crystallized in the triclinic centrosymmetric space group P1̅ (No. 2). The reported materials exhibit chain structures consisting of MoO(6) octahedra and asymmetric SeO(3) polyhedra. Complete characterizations including IR spectroscopy and thermal analyses for the compounds are also presented, as are dipole moment calculations. In addition, the powder second-harmonic-generating (SHG) properties of noncentrosymmetric polar BaMo(2)O(5)(SeO(3))(2) have been measured using 1064 nm radiation. Through powder SHG measurement, we are able to determine that BaMo(2)O(5)(SeO(3))(2) has a SHG efficiency of approximately 80 times that of α-SiO(2). Additional SHG measurements reveal that the material is phase-matchable (type 1). A detailed cation size effect on the symmetry and framework structure is discussed.
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ABSTRACT: The replacement of NbO6 octahedra in Pb2NbO2(SeO3)2Cl by the TiO5F octahedra in Pb2TiOF(SeO3)2Cl induced a very large SHG enhancement from 2.3 × to 9.6 × KDP (KH2PO4), and both materials are type-I phase matchable. Theoretical calculations based on DFT methods indicate that the inclusion of F(-) anions in the d(0)-TM octahedral coordination unit has a great impact on the band structure and the SHG enhancement of the material.Chemical Communications 09/2013; · 6.38 Impact Factor