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• Deep-UV nonlinear optical (NLO) crystals of NaBe 2 BO 3 F 2 were successfully grown. • Calculated refractive indices suggest NaBe 2 BO 3 F 2 is a viable deep-UV NLO crystal. • The structure-property relationships are compared across the entire KBBF family. The deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystal NaBe 2 BO 3 F 2 (NBBF) is grown by the spontaneous nucleation method with the dimensions up to 20 × 20 × 1.5 mm3. The crystal structure was determined using single-crystal x-ray diffraction analysis and its space group was defined as C2 , which belongs to the biaxial class. The optical properties including the transmittance and the NLO coefficients were first determined. The band structure and density of states of NBBF were also calculated. Based on the calculated refractive indices, the Sellmeier equations were fitted to evaluate its ability for deep-UV laser generation. Our results suggest that NBBF is a viable deep-UV NLO crystal. [ABSTRACT FROM AUTHOR]

A new chloride borate, Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl, was obtained when exploring potential phosphor materials. It belongs to orthorhombic system, Pnma space group, with cell parameters of a = 6.965(1) Å, b = 16.546(3) Å, c = 9.557(1) Å and Z = 4. Ba 5- x Sr x (BO 3 ) 3 Cl ( x = 0, 0.5, …to 5) was synthesized and the cell volumes of the solid solutions were obtained by Rietveld refinement. Detailed structure description of Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl was conducted and the structure comparison between Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl and M 5 (BO 3 )X (M = Ba or Sr, X = Cl or F) was illustrated. In Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl, there are hexagonal tunnels extending along a -axis, which is the main feature of apatite family compounds. The density functional theory calculation suggested that in Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl space group Pnma is more energy favourable than C 222 1 . DSC-TG showed that Ba 1.31 Sr 3.69 (BO 3 ) 3 Cl is stable up to 950 °C and Raman and Infrared spectroscopy demonstrate the existence of planar (BO 3 ) 3- in the structure. [ABSTRACT FROM AUTHOR]

• Single crystal structure of a novel ultraviolet NLO tourmaline was solved. • Sellmeier equations were obtained by fitting the measured refractive indices. • Phase matching range of the title crystal is obtained from the Sellmeier equations. • The linear and NLO properties were investigated by the experimental and theory calculation. Transparent tourmaline NaAl 9 (BO 3) 3 Si 6 O 21 OH is first reported by combining experimental and theory calculation methods, which exhibits potential ultraviolet nonlinear optical properties. [Display omitted] Tourmaline, as an important mineral, has received intensive interest, since it is not only a valuable gemstone, but also is a piezoelectric or pyroelectric material, due to the polar structural configuration. However, its nonlinear optical (NLO) properties were not explored so far, because a transparent crystal with high transmittance is scarce, being essential to optical functional materials. Here, we report a novel ultraviolet (UV) NLO tourmaline crystal with chemical composition NaAl 9 (BO 3) 3 Si 6 O 21 OH for the first time by combining first-principles analysis and experimental measurements. It exhibits a short UV absorption edge, considerable second harmonic generation effect and moderate birefringence, thereby facilitating its phase-matching coherent beam output in the range from visible to UV regions. [ABSTRACT FROM AUTHOR]

The new ternary sulfide Sn 2 SiS 4 has been synthesized via high-temperature solid state reaction. It crystallizes in the centrosymmetric space group P2 1 / c of the monoclinic system. In the structure, the Sn 2+ cations are coordinated to a heavily-distorted octahedron of six S atoms or a pentagonal pyramid of six S atoms, both geometries clearly demonstrating the effect of the stereo-chemically active electron lone pair on the Sn coordination environment. These SnS 6 polyhedra and the SiS 4 tetrahedra are connected to each other via corner and edge-sharing to generate a three-dimensional framework. Based on the diffuse reflectance measurement and the electronic structure calculation, Sn 2 SiS 4 has an indirect band gap of 2.00 eV. Interestingly, Sn 2 SiS 4 exhibits an efficient visible-light-driven photocatalytic activity pertaining to Rhodamine B (RhB) degradation, which is superior to the important photocatalyst C 3 N 4 . Moreover, the photocatalytic mechanism was also elucidated based on the active species trapping experiments. [ABSTRACT FROM AUTHOR]

The first two members in the quaternary A/A′/M/Q (A = alkali metal; A′ = alkaline-earth metal; M = As, Sb, Bi; Q = S, Se, Te) system, namely the KBaMSe 3 (M = As, Sb) selenides, have been synthesized by solid state reactions. They are isostructural and crystallize in the centrosymmetric space group P 2 1 / c of the monoclinic system. In the structure, the trivalent M atom (M = As, Sb) is coordinated to three Se atoms forming a trigonal pyramid with the Se atoms serving as the triangle base, showing the stereochemical activity of the ns 2 lone pair electron. The MSe 3 (M = As, Sb) trigonal pyramids are totally isolated from each other with K + and Ba 2+ cations located between them. The optical band gaps of 2.26 (2) eV for KBaAsSe 3 and 2.04 (2) eV for KBaSbSe 3 , were deduced from the diffuse reflectance spectra. The first principles calculations were performed to study the electronic structures of KBaMSe 3 (M = As, Sb) compounds and the results indicated that these two compounds are indirect band gap semiconductors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three new chalcohalides: Ba4Ge2PbS8Br2, Ba4Ge2PbSe8Br2 and Ba4Ge2SnS8Br2 have been synthesized. [•] The MQ5Br octahedra and GeQ4 tetrahedra form a three-dimensional framework with Ba2+ in the channels. [•] Band Gaps and electronic structures of the three compounds were studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new type of phosphomolybdate K2Bi(PO4)(MoO4) photocatalyst was successfully synthesized. [•] The products synthesized at 600°C were mainly composed of nano-cubes. [•] The indirect band gap of K2Bi(PO4)(MoO4) has been determined to be 2.93eV. [•] K2Bi(PO4)(MoO4) synthesized at 600°C exhibits the highest photocatalytic activity. [•] The electronic structure was calculated by density functional calculations. [ABSTRACT FROM AUTHOR]