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It is generally considered difficult for traditional sulfates to exhibit strong second harmonic generation (SHG) responses and large birefringence values because SO4 groups are nonpolar tetrahedral structures.

To obtain new nonlinear optical (NLO) materials with a large second harmonic generation (SHG) effect has always been a great challenge. We have synthesized the first metal borate-iodate NLO crystal, Be2 (BO3 )(IO3 ) (BBIO), by multicomponent modification of KBe2 BO3 F2 (KBBF), in which the structural features of KBBF were maintained and (IO3 )- groups were connected to honeycomb [Be2 BO3 O2 ]∞ layers. As the first KBBF family member with mixed anionic groups, BBIO benefited from the synergistic effect of (IO3 )- , (BO3 )3- and (BeO4 )6- groups, and exhibited a very strong SHG response of ≈7.2×KH2 PO4 (KDP, @1064 nm) and a large birefringence (Δn) of 0.172 at 1064 nm. BBIO may, unexpectedly, optimize growth habits via van der Waals forces. This study presents borate-iodate as a new NLO material and it demonstrates opportunities in KBBF structural engineering.

The first tellurium(II) thiourea sulfate semiorganic nonlinear optical (NLO) material, Te(CS(NH2)(2))(4)SO4 center dot 2H(2)O, was successfully obtained using the slow evaporation technique. The structure of this metal-free crystal featured three types of NLO-active units, namely CS(NH2)(2), (SO4)(2-), and (TeS4)(6-), which synergistically contributed to its moderate second harmonic generation response (2.4 x KDP@1064 nm) and large birefringence (0.210@ 546.1 nm). Remarkably, this is the first example in which the quadrangular (TeS4)(6-) groups significantly contributed to the SHG effect and birefringence, and the first principles calculations revealed its special mechanism of NLO activity. These findings highlighted the exploration of semiorganic NLO materials and provide new opportunities for the discovery of new NLO crystals.

[PO4]3− possesses small microscopic second-order susceptibility and polarizability anisotropy, which inherently result in weak second-harmonic generation (SHG) and small birefringence. Herein, a new noncentrosymmetric phosphate, [C(NH2)3]3PO4·2H2O, was successfully designed and synthesized by a solution evaporation method. [C(NH2)3]3PO4·2H2O without metal ions is composed of planar conjugated guanidine cations and PO4 tetrahedrons, which are connected by hydrogen bonds, forming a three-dimensional network. Physical property measurements indicate that the title compound displays an SHG response of 1.5 × KH2PO4 (KDP) and a larger birefringence (0.055@546.1 nm) compared with most reported ultraviolet nonlinear optical phosphates. Furthermore, first-principles calculations reveal that the π-conjugated planar [C(NH2)3]+ cations and [PO4]3− groups are responsible for its excellent linear and NLO properties.

An alkaline-earth-metal iodate fluoride, Ba(IO3)F (1), was discovered by introducing F atoms into alkaline-earth-metal iodates via a hydrothermal method. The pseudo-two-dimensional (2D) [BaF]+ laye...

An ammonium-containing metal iodate fluoride compound, (NH4 )Bi2 (IO3 )2 F5 , featuring a two-dimensional double-layered framework constructed by [BiO2 F5 ]6- and [BiO4 F4 ]9- polyhedra, as well as [IO3 ]- groups, was successfully synthesized. The well-ordered alignment of these SHG-active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (Eg =3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS2 ). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.

Robinia pseudoacacia (R. pseudoacacia) is a well reported plant species for heavy metal phytoremediation, and it was capable to improve Cd uptake efficiency after inoculated with plant growth promoting endophytes. However, the knowledge on R. pseudoacacia associated endophytes in field condition and the relationship between these microbial communities and heavy metal uptake capacities are still scarce. In this study, the characteristics of heavy metal bioaccumulation and translocation in R. pseudoacacia, and the structure and function of its endophytic bacterial communities were revealed. The results showed that heavy metal pollution made microbes more sensitive to the environment as the diversity (Shannon) of endophyte community decreased but the abundance (Chao) increased. Redundancy analysis (RDA) also showed that heavy metals were the key factor affecting the composition of endophyte. In the co-occurrence network, 27 keystone taxa mainly from Actinobacteria, Proteobacteria and Firmicutes occupied the dominant niches, among which 16 OTUs mainly from lactobacillus, bacteroides, staphylococcus, methylorubrum and bifidobacterium were positively related to bioaccumulation and translocation of Cd, Cu, Pb and Zn. Besides, heavy metal stress enhanced the functional adaptability of endophytic bacteria community. Related predicted genes were enriched in immune response, physiological metabolism pathway and stress-resistant enzyme synthesis. This study showed that heavy metal stress enhanced the structural and functional adaptability of endophyte community and keystone taxa played significant role in improving the efficiency of phytoremediation.

To obtain new nonlinear optical (NLO) materials with a large second harmonic generation (SHG) effect has always been a great challenge. We have synthesized the first metal borate-iodate NLO crystal, Be

An alkaline-earth-metal iodate fluoride, Ba(IO

Two unprecedented metal borate-iodates, Sr[B(OH)4](IO3) (SBIO) and Li4Sr5[B12O22(OH)4](IO3)2 (LSBIO), were synthesized via the strategy of introducing (IO3)− into borates. In particular, the LSBIO possessed a new B12O26 fundamental building block (FBB). The two compounds integrated the advantages of both pure iodates and borates, showing enlarged band gaps and birefringence. Moreover, diverse B–O FBBs achieved the modulation of birefringence. This work reported the first two examples of borate-iodates.

[SO4]2−, a tetrahedral anionic group similar to [PO4]3−, possesses small microscopic second order polarizability and polarizability anisotropy, which tends to result in a weak second harmonic generation effect and small birefringence. Here, three non-centrosymmetric A2Bi2(SO4)2Cl4 (A = NH4, K, Rb) compounds were obtained by an evaporation solution method, which exhibit strong SHG effects of about 4.8, 5.5, and 5.3 × KDP, as well as a large birefringence of 0.055, 0.056 and 0.047 at 1064 nm, respectively. The three compounds exhibit the largest SHG effects among the reported sulfate NLO materials. The first-principles calculations elucidated that the large SHG effects and birefringence were mainly attributed to the synergistic effect of the BiO5Cl2 and [SO4]2− groups. This work may give feasible guidance for the subsequent exploration of sulfate NLO crystals with a large SHG effect and birefringence.

Pr3+-doped LaMgAl11O19 (LMA) crystals have been successfully grown by the Czochralski method with different concentrations ranging from 0.5 to 10.0 mol%. Crystalline quality and the phonon energy were determined by X-ray diffraction and Raman measurements. Spectroscopic parameters based on absorption spectra were systematically calculated using the modified Judd-Ofelt theory. The fluorescence results indicate a large dependence on the factor of doping concentration. The 3P0→3F2 transition red laser channel has the largest emission cross section at 10.7 × 10−20 cm2 for 5.0 mol% Pr:LMA. The fluorescence lifetime of the 3P0 energy level is determined to be 32.6 μs at room temperature with a quantum efficiency of 82.9% for a 5.0 mol% Pr3+-doped sample. The overall spectral properties confirm that Pr:LMA is a promising candidate for visible laser operation.

An ammonium-containing metal iodate fluoride compound, (NH

Two unprecedented metal borate-iodates, Sr[B(OH)

The palladium-catalyzed direct arylation of polyfluoroarenes with organosilicon reagents was achieved by establishing general reaction conditions. This protocol was compatible with a broad range of functional groups and offered the desired products in moderate to good yields.

The crystal structures of a series of new compounds with the composition FeSr(2)LnCu(2)O(7+delta) (Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, and Yb) that were successfully synthesized by solid-state reaction are investigated. The Rietveld refinement of the X-ray diffraction data shows that the samples exhibit a transition from a tetragonal system with space group P4/mmm for light rare earths Ln = La, Nd, Sm, Eu, and Gd to an orthorhombic system with space group Pmmm for heavy rare earths Ln = Dy, Ho, Er, and Yb. The oxygen contents of the samples are chemically determined by the iodometric titration. The room-temperature Mossbauer spectroscopy of (57)Fe in FeSr(2)GdCu(2)O(7+delta) is used to study the site distribution of Fe between the 1a and 2g sites in the as-synthesized in the air samples and O(2)-annealed samples, respectively. In the as-synthesized sample, there are about 67% of Fe ions residing in the la site, whereas in the 02-annealed sample, there are about 61% of Fe ions residing on the la site. Magnetization measurements indicate that Z changes with temperature in a Curie-type manner. Resistance measurements indicate that these samples have a semiconductor-like behavior and their band gap is related to their structural type and the radius of rare earth ions.