Two Isostructural Multi-metal Borates: Syntheses, Crystal Structures and Characterizations of M_3LiNa_4Be_4B_(10)O_(24)F(M = Sr, Cd)

Two new isostructural multi-metal beryllium borates, m^3 Li Na4Be4B10O24F（M = Sr（1）, Cd（2））, have been synthesized by spontaneous crystallization. The structures were verified by single-crystal X-ray crystallography. The compounds crystallize in the trigonal space group R 3, with a = b = 9.4645（1） A, c = 38.842（8） A, V = 3013.2（6） A3, Z = 6, F（000） = 2568, Dc = 3.005 g/cm^3, Mr = 908.9, R = 0.0327, w R = 0.0678, μ = 8.160 mm-1 for Sr3 Li Na4Be4B10O24F and a = b = 9.3019（8） A, c = 37.782（7） A, V = 2831.12（9） A3, Z = 6, F（000） = 2748, Dc = 3.459 g/cm^3, Mr = 983.24, R = 0.0158, w R = 0.0455, μ = 3.586 mm-1 for Cd3 Li Na4Be4B10O24F. The structures are characterized by an infinite two-dimensional [Be8B16O40F2]∞ double layer bridged by [B12O24] groups like a sandwich structure, while the cations reside in tunnels along different directions. UV-vis-IR diffuse reflectance spectroscopy demonstrates that their cut-off edges are below 200 nm. Thermal analysis shows that they melt incongruently and their melting points are around 740-770 ℃.

Growth and optical properties of Pr^(3+):La_2CaB_(10)O_(19) crystal

Pr3+ doped La2CaB10O19 crystal were grown by the top-seeded solution growth(TSSG) method.The absorption spectra,emission spectra and lifetime were measured at room temperature.The J-O parameters(Ωt,t=2,4,6),the radiative transition probabilities AJ,J ,oscillator strengths PJ,J ,radiative lifetime τ,fluorescence branch ratios βJ and the value of integrated emission cross section have also been calculated.Five main absorption bands,3H4 to 3P1+3P2,3P0,1D2,3F3 + 3F4 and 3F2,were observed in the absorption spect...

Synthesis of Polycrystalline Nd∶YAG Nanopowders Used for Sintering Transparent Ceramics via Gel Combustion

Polycrystalline nano-sized neodymium doped yttrium aluminum garnet (Nd∶Y3Al5O12, Nd∶YAG) powders were synthesized via a gel combustion method using nitrates and citric acid as starting materials. The evolution of phase composition and micro-structure of the powders were characterized by X-ray powder diffraction, thermogravimetry/differential thermal analysis and scanning electron microscopy. Well-crystallized Nd∶YAG nano-sized powders could be obtained at 950 ℃ for 2 h. The resultant powders are well dispersed, have a relatively narrow size distribution with an average particle size of approximately 50 nm, and show excellent sinterability. These powders can be densified to 99.2% of the theoretical density by HP sintering at 1700 ℃ for 3 h under 20 MPa nitrogen pressure.

Generation of Ultraviolet Radiation at 266 nm with RbBe_(2)BO_(3)F_(2) Crystal

High-average-power fourth-harmonic generation (4thHG) of an Nd:YAG laser is achieved with a RbBe_(2)BO_(3)F_(2) (RBBF) costal.A maximum output power of 3 W at 266nm is obtained.To our knowledge,this is the first time that efficient 4th HG is realized with RBBF.The angular bandwidth of 4th HG is also measured.

Deep Ultraviolet Harmonic Generation with KBe_(2)BO_(3)F_(2) Crystal

A special prism coupling technique with the KBe_(2)BO_(3)F_(2) crystal is adopted to produce deep ultraviolet light including the fourth harmonic from an Nd:YAG laser,for which a conversion efficiency as high as 10%has been obtained.

Crystal Structure of Lithium Yttrium Borate LiY_6O_5(BO_3)_3

Single crystals of LiY6O5（BO3）3 were obtained by the flux method and its structure was determined by a four-circle automatic diffractometer with a MoKα radiation. It crystallizes in monoclinic, space group P21/n with a = 8.330（3）, b = 15.444（4）, c = 8.780（3）°A,β = 91.85（3）°, V = 1129.0（6）°A^3, Z = 4, Mr= 796.83, F（000） = 1456, μ = 30.567 mm^-1, Dc= 4.688 g/cm^3, the final R = 0.0722 and wR = 0.1304. It exhibits a three-dimensional fiamework of yttrium-oxygen polyhedra interconnected by common edges and corners. B and Li atoms are located in the planes and cavities formed by oxygen atoms, respectively.

Polymorphism of LiCdBO_(3):Crystal structures,phase transitions and optical characterizations

1.Introduction Inorganic borate crystals have received considerable attention in many applications as nonlinear optical(NLO)crystals,birefringence crystals and scintillator materials[1-3].Recently,it is a well-known strategy for designing new NLO materials by utilizing NLO-active units.

Nanostructured yttrium aluminum garnet powders synthesized by co-precipitation method using tetraethylenepentamine

Tetraethylenepentamine(C8H23N5,TEPA) has been used as a novel precipitant to synthesize yttrium aluminum garnet(Y3Al5O12,YAG) precursor from a mixed solution of aluminum and yttrium nitrates via a normal-strike co-precipitation method without controlling the pH value during precipitation process.The original precursor was analyzed by thermogravimetry/differential scanning calorimetry(TG/DSC).The evolution of phase composition and micro-structure of the as-synthesized YAG powders were characterized by X-ray ...

Widely tunable continuous-wave visible and mid-infrared light generation based on a dual-wavelength switchable and tunable random Raman fiber laser

Nonlinear frequency conversion of wavelength agile and high-power random fiber lasers can provide a promising way to generate continuous-wave(CW)visible and mid-infrared(MIR)light with unique properties such as the continuous modeless spectrum,low temporal/spatial coherence,and high temporal stability.Here,we report a dual-wavelength switchable and tunable random Raman fiber laser(RRFL)based on a phosphosilicate fiber that has two Raman gain peaks for the first time and demonstrate its superior capability to generate widely tunable CW visible and mid-infrared light via nonlinear frequency conversions.By using the combination of a tunable pump and two tunable gratings in Littrow configuration that can provide separated point feedback for the two Stokes wavelengths corresponding to silica-and phosphorus-related Raman peaks,the spectrum of an RRFL can be flexibly manipulated for the aim of nonlinear frequency conversions,including single-wavelength tunable emission at the 1.1μm or 1.2μm band for second-harmonic generation(SHG),dual-wavelength simultaneously tunable emission at the 1.1μm and 1.2μm bands for the sum-frequency generation(SFG),and dual-wavelength separation tunable emission for difference-frequency generation(DFG).As a result,with the combination of SHG and SFG in a periodically poled lithium niobate crystal array,we experimentally demonstrate the broadest tuning range(560-630 nm)of visible light generated from an RRFL,to the best of our knowledge.The tunable MIR light in the range of 10.7-12.3μm is also demonstrated through DFG of an RRFL operating in separation tunable dual-wavelength emission mode in a Ba Ga4Se7(BGSe)crystal,which is the first realization of>10μm CW DFG in the BGSe crystal.We believe the developed dual-wavelength switchable and tunable RRFL can provide a new compact,robust,and cost-effective platform to realize broadly tunable light in both the visible and MIR regions,which can also find potential applications in imaging,sensing,and temporal ghost imaging in various spectral bands.

Design and Exploratory Synthesis of Infrared Nonlinear Optical Metal Chalcogenides: Recent Advances and Future Perspectives

Design and exploratory synthesis of novel infrared nonlinear optical chalcogenides have drawn extensive concerns owing to their excellent overall performance and important role in laser industry.During the past decades,a large number of infrared nonlinear optical chalcogenides have been developed and many effective design strategies have been summarized,which illuminates the path of future explorations.In this perspective,we discuss the feasibility and effectiveness of the representative design ideas.Moreover,we point out some topics to be investigated and discuss the future research directions.