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Four new phosphates with a PbM(PO4)X formula were synthesized and characterized. Their crystal symmetry, thermal stability and band gap are decreased with an increase of the atomic number of halogen, while the rule for birefringence is the opposite.

AgTeO2F and Ag2(TeO2F2) are the first silver fluorotellurites, while Ag3F3(TeF6)(TeO2)12 is the first silver fluoride tellurite. Ag3F3(TeF6)(TeO2)12 features an NCS mixed valence Te oxyfluoride with an SHG intensity of about 70% that of commercial KDP.

A new polar iodate, Ba2Ce(IO3)8(H2O), with flower-shaped [Ce(IO3)8(H2O)]4− polyanions, exhibits a second-harmonic-generation (SHG) response about 0.2 times that of KH2PO4. The SHG response is closely related to the arrangement of the iodate groups.

The designed [M(OH)2]3(IO3)(SeO4)·H2O (M = Ga and In) feature ∞[MO2(OH)2]3− layers composed of M3O6(OH)9 trimeric units capped by SeO4 and IO3 groups from different sides of the layers. They exhibit moderate SHG effects and large LIDT values.

LaBS3 possesses a large SHG effect, high laser-induced damage threshold, wide band gap, and high thermal stability.

Three new potassium rare earth carbonates KRE(CO3)2 (RE = Eu, Gd, Tb) with strong photoluminescence and large birefringence were synthesized successfully.

Cd4REO(BO3)3 (RE = Sm, Eu, Tb) obtained by introducing non-centrosymmetric (NCS) groups into borates have high stability and good SHG signals and fluorescence performance.

K3V2O3F4(IO3)3, which is the first metal vanadium iodate containing two different V-centered polyhedra, exhibits a strong SHG effect of 1.3 × KTP and a large birefringence of 0.158 @ 2050 nm.

The first metal iodate-phosphates, namely, Cd2(IO3)(PO4) and Cd1.62Mg0.38(IO3)(PO4), display novel crystal structures and comprehensive SHG performance.

With reference to Sr2Be2B2O7, two new short-wave ultraviolet beryllium-free Sr2Be2B2O7-type zincoborates, Na3AEZn2B3O9 (AE = Mg and Ca), were successfully designed by a cosubstitution strategy and synthesized by a molten-salt method.

A promising nonlinear optical material, CaCe(IO3)3(IO3F)F, containing both IO3− and IO3F2− anions, has been reported.

Two alkali tin(II) phosphates, namely, Rb[SnF(HPO4)] and Rb(Sn3O)2(PO4)3, were synthesized through mild hydrothermal methods. They belong to the orthorhombic Pnma and Pbcn space groups, respectively. Rb[SnF(HPO4)] features a layered structure based on 1D [SnF(HPO4)]∞ chains interconnected by hydrogen bonds, with Rb+ cations located at the interlayer space. For Rb(Sn3O)2(PO4)3, each pair of [Sn3O]4+ clusters is bridged by a pair of [P(1)O4]3- tetrahedra to build a 1D [Sn-P-O]∞ chain. These 1D [Sn-P-O]∞ chains are further cross-linked though [P(2)O4]3- tetrahedra to construct a 3D network with 7- and 10-membered-ring channels. The tin(II) ions in Rb[SnF(HPO4)] and Rb(Sn3O)2(PO4)3 with stereochemically active lone pairs (SCALPs) significantly enhance the birefringences of metal phosphates: Δn = 0.147@1064 nm for Rb[SnF(HPO4)] and 0.082@1064 nm for Rb(Sn3O)2(PO4)3.

A novel barium zinc borate contains π-conjugated [B

An organic-inorganic hybrid polyiodate, namely, [o-C5 H4 NHOH]2 [I7 O18 (OH)]⋅3 H2 O (I), featuring a novel branched polyiodate chain has been obtained by evaporation method. [o-C5 H4 NHOH]2 [I7 O18 (OH)]⋅3 H2 O (I) crystalizes in the polar space group Ia and features an [I7 O18 (OH)] ∞2- branched polyiodate chain in which [I3 O9 ]3- trimers are grafted on the same side of the one-dimensional (1D) chain based on [I4 O11 (OH)]3- tetramers. The asymmetric organic amine groups are beneficial to the polymerization of iodate groups and inducing the formation of the non-centrosymmetric (NCS) structure. Compound I exhibits a rather large Second-Harmonic- Generation (SHG) signal of 8.5×KH2 PO4 (KDP) upon 1064 nm laser radiation, a moderate band gap of 3.90 eV and a high laser-induced-damage-threshold (LIDT) of 182.34 MW cm-2 , hence it is a promising new SHG material. The relationship between the structures of the organic amine groups and the overall structures has been also analyzed.

A novel salt-inclusion fluoroiodate [GaF(H2O)][IO3F] derived from CsIO2F2 was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H2O)]2+ framework serves as a template for the favorable assembly of the polar [IO3F]2− groups and contributes to the nonlinear coefficient, [GaF(H2O)][IO3F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH2PO4 (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO2F2 (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H2O)][IO3F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS2 of the reported iodates. All these results signify that [GaF(H2O)][IO3F] is a promising nonlinear optical (NLO) crystal. This work also proposes that anisotropic polycation substitution is an effective approach to optimize the SHG effect and develop excellent NLO materials., A novel salt-inclusion fluoroiodate nonlinear optical material, [GaF(H2O)][IO3F], is derived from CsIO2F2 through polycation substitution, and it exhibits an intense SHG effect of 10 times that of KH2PO4 and improved overall performance.

Two new borogermanate/borosilicate fluorides, namely, NaBa

The first NLO-active metal iodate-phosphates, namely, Cd

A new anhydrous rare-earth metal iodate fluoride, Ce(IO3)2F2, was rationally designed and synthesized. Ce(IO3)2F2 features unique zigzag ∞[CeF2]2+ chains that are bridged by IO3– groups, creating a...

Explorations of new types of borates are important because of their promising application in diverse fields. A new bismuth-containing boroselenite, Bi2[B2(SeO3)6], has been obtained through high-te...

Playing a crucial role in light-emitting diode (LED) illumination sources, the blue light-emitting materials are commonly obtained by doping rare-earth metal ions. Considering the high price, non-r...

Two new antimonous phosphates, namely Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2, have been successfully prepared through mild hydrothermal reactions. Ba3Sb2(PO4)4 features a 1D [Sb(PO4)2]3- chain structure separated by Ba2+ cations while Cd3Sb2(PO4)4(H2O)2 presents a 2D [Sb(PO4)2]3- layered structure with Cd2+ located at the interlayer space. The [Sb(PO4)2]3- chain in Ba3Sb2(PO4)4 is the first example of 1D antimonous phosphate structure, and Cd3Sb2(PO4)4(H2O)2 represents the first d10 transition metal antimonous phosphate. Based on UV-vis-NIR spectra, both Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2 can display large optical band gaps (4.30 and 4.36 eV, respectively). But their transparent ranges are quite different because of the coordination water of Cd3Sb2(PO4)4(H2O)2 (500-2000 and 500-1300 nm for Ba and Cd compounds). The anhydrous Ba3Sb2(PO4)4 shows high thermal stability in the nitrogen atmosphere (900 °C). Because of the incorporation of the lone pair cation of Sb(III), the birefringence of Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2 has been enhanced to 0.086 and 0.053 at 532 nm, respectively.

Cyanurate motifs are emerging functional basic blocks (FBBs) for nonlinear optical (NLO) materials and birefringent materials. Herein, we report two new potassium lead(II) hydroisocyanurates, namely, K2Pb(H2C3N3O3)4(H2O)4 (I) and K3Pb(H2C3N3O3)5(H2O)6 (II). I and II belong to acentric Cm and centric C2/m, respectively. Compound I features a novel 3D network formed by 2D [K2PbO8(H2O)4]12− anionic layers interconnected by (H2C3N3O3)− anions. The 2D [K2PbO8(H2O)4]12− anionic layer is composed of 1D chains of edge-sharing K(1)O6 and K(2)O8 being further interconnected by 8-coordinated Pb2+ ions. Compound II exhibits a characteristic 3D framework based on 2D [K3PbO11(H2O)6]17− anionic layers interlinked through (H2C3N3O3)− groups, and the 2D [K3PbO11(H2O)6]17− anionic layer is based on K–O/H2O chains bridged by Pb2+ ions. Powder second harmonic generation (SHG) measurements of I revealed a moderate SHG response of approximately 2.6 × KDP with a type I phase-matching behavior under 1064 nm laser radiation. Theoretical calculations of I and II revealed their birefringence to be 0.325 and 0.193@532 nm, respectively. Their impressive optical properties mainly stem from stereochemically active lone pair (SCALP) Pb2+ cations and the planar π-conjugated (H2C3N3O3)− groups.

A new SHG material, Ba3[Al(PO4)3], has been rationally designed by expanding the anionic condensation design strategy from atom-sharing to anionic-group-sharing. As the first Ba3[B(PO4)3]-type acentric phosphate, Ba3[Al(PO4)3] is characterized by moderate second-order optical nonlinearity, beneficial type I phase-matching behavior, deep-UV transparency and high thermal stability, favourable for practical applications.

Our exploration of novel inorganic solids with large birefringence in the d10 Metal–Te4+–SO42− system afforded four new sulfate tellurites, Ga2(TeO3)(SO4)(OH)2, In2(TeO3)2(SO4)(H2O), Zn4(Te3O7)2(SO4)2(H2O) and Hg3(Te3O8)(SO4). Notably, Hg3(Te3O8)(SO4) exhibits the largest birefringence at 532 nm (0.184) and 1064 nm (0.166) among the reported metal sulfate tellurites.

A new noncentrosymmetric iron-iodate-fluoride Ba2[FeF4(IO3)2]IO3 was ingeniously obtained based on the centrosymmetric Ba[FeF4(IO3)] through chemical tailoring. Ba2[FeF4(IO3)2]IO3 exhibits a strong phase-matchable second-harmonic generation effect, a large band gap, and a wide mid-infrared transparent window. The chemical tailoring design based on oxide-fluoride anions affords a feasible approach to design nonlinear optical materials.

Fluorine, as the most electronegative element, can replace the oxygen ligands of functional groups under given conditions. These fluoride groups are more or less different from the pure oxide groups in composition, symmetry, polarizability, transmittancy, etc. The rational use of these differences is expected to improve the probability of noncentrosymmetric structures and the comprehensive performance of second-harmonic-generation (SHG) materials. In this feature article, we introduce the recent developments in fluoride selenite and tellurite SHG materials together with highlighting our contributions, including Se(IV) and Te(IV) compounds with (i) d0 transition metal oxyfluoride octahedron, (ii) IIIA metal oxyfluoride octahedron, (iii) fluoride lone pair cation polyhedron, and (iv) other fluoride polyhedron. The future perspectives of fluoride selenite and tellurite SHG materials are also discussed.

The first examples of zirconium fluoroantimonites, namely, K

Through systematic experiments, two novel mercury iodate sulfates, namely, Hg

The first polar molybdenum oxyfluoride in selenite and tellurite systems, namely, Ba(MoO2F)2(SeO3)2 and Ba(MoO2F)2(TeO3)2, was achieved successfully by partial fluorination of MoO6 octahedra under ...