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A new alkaline earth–rare earth iodate, Ba2Ce(IO3)8(H2O), has been synthesised by a hydrothermal method and its structure has been determined by single-crystal X-ray diffraction. Ba2Ce(IO3)8(H2O) crystallises in the polar space group Pna21 (No. 33) with unit cell parameters of a = 15.5042(5) Å, b = 7.8841(3) Å, c = 19.5359(8) Å, V = 2388.00(15) Å3, and Z = 4. The structure of Ba2Ce(IO3)8(H2O) is characterised by zero-dimensional (0D) [Ce(IO3)8(H2O)]4− units separated by Ba2+ cations. Large crystals of Ba2Ce(IO3)8(H2O) with dimensions of a few millimetres have been grown. The UV-vis-NIR transmission spectroscopy measurements of the compound showed that it has a short wavelength absorption edge at 381 nm. Ba2Ce(IO3)8(H2O) exhibits a relatively weak second-harmonic-generation (SHG) response, about 0.2 times that of KDP, which is mainly due to the fact that the polarisation effects of the IO3 groups in the structure largely cancel each other out. The relationships between the structure and the physical properties of Ba2Ce(IO3)8(H2O) have also been calculated theoretically. Ba2Ce(IO3)8(H2O) has a band gap of 2.44 eV, which is determined by the Ce–O and I–O interactions and is larger than those of many simple metal iodates. The introduction of alkaline earth metals favours an increase in band gap. Our work shows that the SHG and birefringence properties are closely related to the arrangement of the functional groups in the compounds. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The first alkali‐metal vanadium iodate fluoride, CsVO2F(IO3), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO2F(IO3)]− framework in CsVO2F(IO3) is built from 0D Λ‐shaped cis‐[VO3F(IO3)2]4− polyanions via corner‐sharing of oxo anions and bridging of the iodate groups. CsVO2F(IO3) displays both a strong second‐harmonic generation (SHG) 1.1 times as strong as KTiOPO4 (KTP) under 2.05 μm laser radiation and high laser‐induced damage threshold (LIDT) of 107.9 MW cm−2. This work provides a new route to design SHG crystals with stable 3D anionic structures from low‐dimensional structural building units. [ABSTRACT FROM AUTHOR]

The first divalent-metal iodate-phosphate, Pb2(IO3)(PO4), has been prepared via the strategy of introducing (IO3)− into phosphate. The structure features a unique 3D network where [Pb(IO3)]∞+ and [Pb(PO4)]∞− layers are alternatively interconnected. The birefringence of Pb2(IO3)(PO4) is greatly increased to 0.060 at 1064 nm. [ABSTRACT FROM AUTHOR]

The first examples of rare‐earth polyiodates, namely, REI5O14 (RE=Y and Gd), have been prepared by hydrothermal reactions of RE2O3 and H5IO6 in H3PO4 (≥85 wt % in H2O), with extremely high yields (>95 %). They crystalize in the polar space group Cm and feature a brand‐new semicircle‐shaped [I5O14]3− pentameric polyiodate anion composed of two IO3 and three IO4 polyhedra. Remarkably, both compounds exhibit very large second‐harmonic generation (SHG) signals (14× and 15×KH2PO4 (KDP) upon 1064 nm laser radiation for Y and Gd compounds, respectively). Our work shows that the hydrothermal reaction in a phosphoric acid medium facilitates the formation of rare‐earth polyiodates. [ABSTRACT FROM AUTHOR]

The first metal iodate fluoride, Bi(IO3)F2, with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO3)F2 crystallizes in the polar space group C2 and features a three-dimensional [BiF2]+ cationic framework with IO3 groups capping the inner walls of the one-dimensional tunnels. This [BiF2]+ cationic framework acts as a template for the assembly of the polar IO3 units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO3)F2 displays a rather wide transmittance window (0.3-11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH2PO4 (KDP) under 1064 nm laser radiation and the same as that of KTiOPO4 (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO3)F2 is a promising nonlinear optical material in the visible and mid-IR region. [ABSTRACT FROM AUTHOR]