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.

An Effective Strategy for Designing Nonlinear Optical Crystals by Combining the Structure‐Directing Property of Oxyfluorides with Chemical Substitution

“…Structurally, only the noncentrosymmetric (NCS) structure can exhibit the SHG response. As for the properties, the excellent NLO crystal must possess i) large SHG response ( d eff ≥ d 36 (KDP)=0.39 pm V −1 for UV; d eff ≥10× d 36 (KDP) for IR), ii) high transmission in the work region, iii) moderate birefringence (0.03–0.1), iv) large band gaps and high laser‐damage thresholds (LDTs) [11–18] . Therefore, it implies that the design of NLO crystals will consist of two aspects: i) constructing a NCS structure, ii) optimizing functional properties.…”

“…10 d 36 (KDP) for IR), ii) high transmission in the work region, iii) moderate birefringence (0.03-0.1), iv) large band gaps and high laser-damage thresholds (LDTs). [11][12][13][14][15][16][17][18] Therefore, it implies that the design of NLO crystals will consist of two aspects: i) constructing a NCS structure, ii) optimizing functional properties.…”

pH Controlled Pathway and Systematic Hydrothermal Phase Diagram for Elaboration of Synthetic Lead Nickel Selenites

“…However, two of them are protonated leading to strongly distorted (Se show a distorted square antiprismatic arrangement with lone pairs of electrons oriented toward the longest oxygen neighbors, similarly to lead coordination in PbMo 2 O 5 (SeO 3 ) 2 . 10 In the crystal structure of III, the NiO 6 octahedra are sharing their vertices with SeO 3 groups, forming a 3D framework encapsulating channels propagating along the [010] direction (Figure 8a). Four independent channels are occupied alternately by divalent lead cations and lone pairs of electrons of the Se 4+ cations.…”

Cation Size Effect on the Framework Structures in a Series of New Alkali-Metal Indium Selenites, AIn(SeO3)2 (A = Na, K, Rb, and Cs)

“…In fact, an examination of 36 examples of SeO 3 polyhedra found in indium selenites materials reveals that the dipole moments range from 6.99 D to 11.00 D, with an average value of 8.01 D. The values are consistent with those reported dipole moments for SeO 3 polyhedra. 25,26,38,39 A complete calculation of dipole moments for the SeO 3 polyhedra is listed in Table 3.…”