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Two new barium borogermanates with two types of novel structures, namely, Ba3[Ge2B7O16(OH)2](OH)(H2O) and Ba3Ge2B6O16, have been synthesized by hydrothermal or high-temperature solid-state reactions. They represent the first examples of alkaline-earth borogermanates. Ba3[Ge2B7O16(OH)2](OH)(H2O) crystallized in a polar space group Cc. Its structure features a novel three-dimensional anionic framework composed of [B7O16(OH)2]13- polyanions that are bridged by Ge atoms with one-dimensional (1D) 10-membered-ring (MR) tunnels along the b axis. The BaII cations, hydroxide ions, and water molecules are located at the above tunnels. Ba3Ge2B6O16 crystallizes in centrosymmetric space group P1¯. Its structure exhibits a thick layer composed of circular B6O16 units connected by GeO4 tetrahedra via corner sharing, forming 1D 4- and 6-MR tunnels along the c axis. Ba1 ions reside in the tunnels of the 6-MRs, whereas Ba2 ions are located at the interlayer space. Both compounds feature new types of topological structures. Second-harmonic-generation (SHG) measurements indicate that Ba3[Ge2B7O16(OH)2](OH)(H2O) displays a weak SHG response of about 0.3 times that of KH2PO4. Optical, thermal stability, and ferroelectric properties as well as theoretical calculations have also been performed. [ABSTRACT FROM AUTHOR]

Two new rubidium iodates, namely, β-RbIO3(HIO3)2 (1, P1) and Rb3(IO3)3(I2O5)(HIO3)4(H2O) (2, P21/c), have been synthesized by hydrothermal reaction and their structures determined by single-crystal X-ray diffraction. Compound 1 exhibits IO3- anions and neutral HIO3 molecules which are interconnected by Rb+ cations into three-dimensional structure. Compound 2 features a two-dimensional layered structure formed by IO3- anions and neutral HIO3 and dimeric I2O5 molecules interconnected by Rb+ cations. Large bulk crystal of 1 with dimensions of several millimeters has been grown. UV-vis-NIR transmission spectroscopy measurements on a slab of a polished crystal of 1 indicated that the crystal possesses a short-wavelength absorption edge onset at 305 nm. Powder second-harmonic generation (SHG) measurements on sieved crystals revealed that 1 is a type I phase-matchable material with an SHG response about 1.5 times that of KH2PO4. The Vickers hardness of crystal of 1 has been measured to be 110 HV, and the laser-induced damage threshold has been confirmed to be 18.26 J/cm² with a laser wavelength of 1064 nm and a pulse duration of 10 ns. Moreover, thermal stabilities and vibrational spectra for both 1 and 2 have also been studied. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis and nonlinear optical (NLO) properties of polar material BaNbO(IO3)5 using the calculation of a complex diaelectric function. It confirms the presence of an unparalleled phase in the material through power X-ray diffraction (XRD). It refers to the results of bond valence calculations, indicating that the Ba, Nb, and I atoms exhibit oxidation states of +2, +5, and +5 respectively.