Syntheses, crystal structures and optical properties of the first strontium selenium(IV) and tellurium(IV) oxychlorides: Sr3(SeO3)(Se2O5)Cl2 and Sr4(Te3O8)Cl4

Zn[Htma][ddm]: An Interesting Three-Dimensional Chiral Nonlinear Optical-Active Zinc-Trimesate Framework

“…However, considering that the discrepancy may be due to the difference between the single crystal model and polycrystalline sample, , the calculation value above is reasonable. Such dielectric function will result in the anisotropic refractive index because the correlations between both are linked by the formula of n 2 (ω) = ε(ω), where n , ω, and ε refer to refractive index, frequency, and dielectric constant, respectively . Figure shows the calculated dispersion of linear refractive index of 1 .…”

AAl(Te4O10) (A = Na, Ag) and K2Ga2(HTe6O16)(HTeO3): Three Aluminum/Gallium Tellurites with Large Birefringence and Wide Band Gap

“…Two Te2O 3 and one Te1O 4 units are interconnected to form a Te 3 O 8 trimer, and the 2D sodium/aluminum tellurite layered structures are further connected into a 3D structure through the Te 3 O 8 trimers (Figure ). It is worth noting that Te 3 O 8 trimers were reported in Hg 3 (Te 3 O 8 )­(SO 4 ) and Sr 4 (Te 3 O 8 )­Cl 4 . , However, the difference is that, in Hg 3 (Te 3 O 8 )­(SO 4 ) and Sr 4 (Te 3 O 8 )­Cl 4 , the lone-pair electrons of Te 3 O 8 are aligned in the same direction, while in 1 , they are arranged along different directions (Figure S7).…”

“…They may be used as nonlinear-optical (NLO) materials, birefringent materials, magnetic materials, and other applications. − Te IV cations when coordinated with O atoms can form three different basic anionic building blocks, namely, [TeO 3 ] 2– , [TeO 4 ] 4– , and [TeO 5 ] 6– , such as the tellurite groups in Ba­(MoO 2 F) 2 (TeO 3 ) 2 , Li 7 (TeO 3 ) 3 F, Ba­(MoOF 2 )­(TeO 4 ), Bi 2 TeO 5 , and so on. These basic anionic building blocks can be further polymerized into zero-dimensional (0D) clusters, one-dimensional (1D) chains, two-dimensional (2D) layers, and even three-dimensional (3D) network structures, such as 0D clusters in Sr 4 (Te 3 O 8 )­Cl 4 , Rb­[Te 2 O 4 (OH) 5 ], CsYTe 3 O 8 , and Ba 2 V 4 O 8 (Te 3 O 10 ), 1D chains in BaLiTe 2 O 5 Cl, Y 2 (Te 4 O 10 )­(SO 4 ), Cd 7 Cl 8 (Te 7 O 17 ), and Nd 2 (MoO 4 )­(Te 4 O 10 ), 2D layers in Zn 4 (Te 3 O 7 ) 2 (SO 4 ) 2 (H 2 O), NdTe 2 O 5 Br, Ba 3 PbTe 6 O 16 , and RbNaTe 8 O 14 (OH) 6 ·8H 2 O, and 3D networks in Ag 3 F 3 (TeF 6 )­(TeO 2 ) 12 (Figure S1). Additionally, when Te IV is coordinated with F and O atoms simultaneously, new basic building blocks TeO 2 F, TeO 2 F 2 , and TeF 3 will be formed, such as the fluorotellurite groups in AgTeO 2 F, Bi 3 F­(TeO 3 )­(TeO 2 F 2 ) 3 , HgTeO 2 F­(OH), and BaF 2 TeF 2 (OH) 2 …”

Rb2SeOCl4·H2O: a polar material among the alkali metal selenite halides with a strong SHG response

“…Moreover, it is reported that the metal selenite halides often form low dimensional structures such as chains and layers because the Se 4+ and halide anions can act as "chemical scissors". 24 So far, many halides of alkaline earth selenite, lead selenite and bismuth selenite have been reported, such as Pb 3 (SeO 3 ) 2 Cl 2 , 25 Pb 3 (SeO 3 )Br 2 , 26 Bi(SeO 3 )Cl, 27 Bi 8 (SeO 3 ) 9 Br 6 , 28 Sr 3 (SeO 3 ) 2 Cl 2 , 29 Sr 3 (SeO 3 )(Se 2 O 5 )Cl 2 30 and InSeO 3 Cl. 31 Almost all of these compounds, unfortunately, are centrosymmetric, except the compound Bi(SeO compounds (where M = alkali cation and X = halide) with the following hopes: (1) in these compounds, the Se 4+ cation may form bonds with halogen anions in addition to bonding to oxygen atoms so as to form noncentrosymmetric anionic groups, and this may strengthen the polarization of the structure and align local asymmetric microscopic units in the favored direction to form a macroscopic polar compound; (2) the alkali metals are more or less different from the alkaline earth metals and the other metals, in terms of electronic behaviour, and they may favor the establishment of a noncentrosymmetric crystal structure and excellent comprehensive properties, as evidenced by the fact that many famous SHG crystals are alkali salts, such as KH 2 PO 4 (KDP), 32 KTiOPO 4 (KTP), 33 LiNbO 3 , 34 KBeBO 3 (KBBF), 35 LiBO 3 (LBO), 36 LiInS 2 , 37 etc.…”