In this study, a series of tetrafluoroborates with non-pi-conjugated [BF4] tetrahedra are investigated systematically by first-principles calculations. Theoretical studies demonstrate that tetrafluoroborates with alkali and/or alkaline-earth metals are more favorable for deep-ultraviolet transmission and are comparable to the classical deep-ultraviolet (deep-UV) material, MgF2. Furthermore, bandgap decrease with the increasing of ionic radii in alkali and/or alkaline-earth metals. Introducing highly polarizable cations with d(10)-configuration or cations with lone pair electrons into the structure will decrease the bandgaps. The birefringence and second harmonic generation effects are not large enough in tetrafluoroborates because polarizability anisotropy and hyperpolarizability in non-pi-conjugated [BF4] tetrahedra are much smaller than those in pi-conjugated groups. However, the second harmonic generation effect for [BF4] tetrahedra has a higher contribution in comparison with that due to birefringence. To effectively synthesize the borate fluorides or fluorooxoborates in the deep-UV region, raw materials with B-F bonds are preferred.

The discovery of new borates with unique structures has always been a growing part of solid-state chemistry, especially for polyborates. Herein, a new aluminoborate, Cs3AlB6O12, has been discovered by a high-temperature solution in a vacuum system. The highly polymerized [B12O24] cluster, unlike the annular configuration in previously reported polyborates, is found in Cs3AlB6O12 for the first time. The different linkage reflected by the local symmetry in cluster makes these borates not isotypic, although the formula of [B12O24] is identical. Experimental measurement performed on Cs3AlB6O12 powder reveals the deep-ultraviolet transparent spectral feature.

Four new alumino-/galloborates RbMT3 (BO3 )2 O3 (M=Ba, Sr; T=Al, Ga) have been synthesized for the first time by using a high-temperature solution method. All the title compounds have Sr2 Be2 B2 O7 -like structures, in which the [BO3 ] triangles and [TO4 ] tetrahedra form the final double-layered configurations with the M- and Rb-site atoms located between and in the double layer, respectively. The structure evolution from Sr2 Be2 B2 O7 to RbMT3 (BO3 )2 O3 series is discussed. The broader energy bandgaps in Al-based borates when compared with Ga-based ones can be entirely attributed to the location of Al/Ga s orbitals near the Fermi surface. Both experimental and computational approaches were used to study their structure-property relationships.

A new alkali-metal iodate, K6(IO6H4)(HI2O6)(HIO3)2(IO3)4·2H2O (KIOH), was successfully grown at room temperature by a slow evaporation method. To our knowledge, the title compound is the first alkali-metal iodate containing isolated [I5+O3] and [I7+O6] units in one structure. Both the bond valence sum and X-ray photoelectron spectroscopy confirmed this phenomenon, which is consistent with the single-crystal data. Also, the theoretical calculation results showed that the title compound is a potential birefringent material. What is more, the low-cost growth of centimeter-sized crystals for the title compound greatly enriches the structural chemistry of the iodate system.

A new telluroborate Rb3BaTeB7O15, with a new type of fundamental building block, namely [B7O16] units, has been synthesized by the high-temperature flux method, and it crystallizes in the monoclinic space groupP2(1)/n(no. 11) with a three dimensional network. To the best of our knowledge, Rb(3)BaTeB(7)O(15)is the first telluroborate that is constructed only by using [TeO3] polyhedra. Meanwhile, the stereochemical activity of the [TeO3] polyhedra was demonstrated by employing theoretical calculations. The UV-vis-NIR diffuse reflectance spectrum, thermal gravimetric results, differential scanning calorimetry curves and infrared spectrum of Rb(3)BaTeB(7)O(15)were characterized and analyzed. In addition, the electronic structures and birefringence were discussed by using the first-principles calculations.

We report the experimental characterization and first principles calculation of linear and nonlinear optical properties of two orthophosphates A3Al2(PO4)3(A = Rb, K).

P–O units are shown to feature distinct polyanionic configurations from [PO3]∞ chains to [P4O12]4− rings.