Properties of a New Nonlinear Optical Crystal CdZn2B2O6

Cadmium dizinc diborate （CdZn2B2O6） single crystals have been grown for the first time. The crystal structure of CdZn2B2O6 is the same as that of the Cd3Zn3B4O12. The x-ray diffraction, infrared and Raman spectra, differential scanning calorimetry analysis and density indicate that the physical and chemical properties of both crystals are very similar. Especially, the nonlinear optical coefficients of CdZn2B2O6 and Cd3Zn3B4O12 crystals are 2.6 and 2.4 times as large as that of KH2PO4 crystal respectively. Chemical etching experiments indicated that these crystals are very stable in neutral solution and not hygroscopic in air at room temperature.

Hydrothermal growth of KTiOPO_(4) crystal for electro-optical application

"New"electro-optical(EO)crystals are hard to find,"old"EO crystals are scarce and each has its own problems,and the demand for high-performance EO crystals by higher power,higher repetition rate,and narrower pulse width laser is realistic and urgent.The EO performance of KTP was recognized as soon as it was discovered,but after more than 40 years of development,the reports,and products of EO devices based on KTP are less than those of other EO crystals,even though KTP is now almost the cheapest nonlinear optical crystal material.In this paper,based on our understanding of the crystal structure of predecessors and ourselves,especially the understanding and practice of quasi-one-dimensional ionic conduction mechanism,we think that crystal growth is the most important reason that affects the controllability of crystal performance.Through a series of science and technology,we realize the growth of large-size crystals with high-optical uniformity,then reduce the absorption of KTP to a very low level,and grow crystals with resistance to electric damage and laser damage.On this basis,reducing the conductivity and improving the uniformity of optical,electrical,piezoelectric,and ferroelectric properties are emphasized.The extinction ratio,piezoelectric ringing effect,and thermal influence of the EO switch based on KTP crystal are tested,and some publicly available progress of using KTP EO devices in high-repetition rate laser is listed.Finally,we are looking forward to the development of KTP EO crystal for the laser system to EO generator for integrated optics.

LnCu_(3)(OH)_(6)Cl_(3) (Ln=Gd, Tb, Dy): Heavy lanthanides on spin-1/2 kagome magnets

The spin-1/2 kagome antiferromagnets are key prototype materials for studying frustrated magnetism.Three isostructural kagome antiferromagnets LnCu_(3)(OH)_(6)Cl_(3)(Ln=Gd,Tb,Dy)have been successfully synthesized by the hydrothermal method.LnCu_(3)(OH)_(6)Cl_(3) adopts space group P3m1 and features the layered Cu-kagome lattice with lanthanide Ln3+cations sitting at the center of the hexagons.Although heavy lanthanides(Ln=Gd,Tb,Dy)in LnCu_(3)(OH)_(6)Cl_(3) provide a large effective magnetic moment and ferromagnetic-like spin correlations compared to light-lanthanides(Nd,Sm,Eu)analogues,Cu-kagome holds an antiferromagnetically ordered state at around 17 K like YCu_(3)(OH)_(6)Cl_(3).

Atomic structures and carrier dynamics of defects in a ZnGeP_(2) crystal

ZnGeP_(2)[ZGP] crystals have attracted tremendous attention for their applications as frequency conversion devices.Nevertheless,the existence of native point defects,including at the surface and in the bulk,lowers their laser-induced damage threshold by increasing their absorption and forming starting points of the damage,limiting their applications.Here,native point defects in a ZGP crystal are fully studied by the combination of high angle annular dark-field scanning transmission electron microscopy[HAADF-STEM] and optical measurements.The atomic structures of the native point defects of the Zn vacancy,P vacancy,and Ge-Zn antisite were directly obtained through an HAADF-STEM,and proved by photoluminescence[PL] spectra at 77 K.The carrier dynamics of these defects are further studied by ultrafast pump-probe spectroscopy,and the decay lifetimes of 180.49,346.73,and 322.82 ps are attributed to the donor V_(p)^(+)→valence band maximum[VBM] recombination,donor Ge^(+)_(Zn)→VBM recombination,and donor–acceptor pair recombination of V_(p)^(+)→V^(-)_(Zn),respectively,which further confirms the assignment of the electron transitions.The diagrams for the energy bands and excited electron dynamics are established based on these ultrahigh spatial and temporal results.Our work is helpful for understanding the interaction mechanism between a ZGP crystal and ultrafast laser,doing good to the ZGP crystal growth and device fabrication.

Special Issue on the 120th Anniversary of Shandong University

This special issue is committed to celebrating the 120th Anniversary of Shandong University(SDU)(15th October,2021),as well as capturing the most fascinating research works and reviews from all aspects of optics and photonics,including but not limited to,optoelectronic functional crystals,basic science,applied and engineering research and applications.

Syntheses, characterization, and theoretical calculation of Rb2Mg3（P2O7）2 polymorphs with deep-ultraviolet cutoff edges

By the combination of the isolated P2O7 dimers and Mg O4 tetrahedra,α-andβ-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method.α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space group P212121,whileβ-Rb2Mg3(P2O7)2 crystallizes in centrosymmetric P21/c.Both structures contain a three dimensional[Mg3P4O14]^2- anionic framework,while Rb^+ cations are in the space.Structure analyses show that the isolated P2O7 dimers can easily adjust their variable configurations and orientations to fit the different coordination environments of the cations,which is conducive to the formation of polymorphs.The phase transformation process fromα-toβ-Rb2Mg3(P2O7)2 was further investigated by powder X-ray diffraction and thermal gravimetric/differential scanning calorimetry measurements.In addition,UV-vis-NIR diffusion spectra indicate both materials have deep-ultraviolet cut-off edges(below 190 nm).α-Rb2Mg3(P2O7)2 is second-harmonic generation(SHG)-active and the origin of SHG response was investigated by the SHG density calculations.The first-principle calculations were also carried out to illuminate their structure-property relationships.

Combustion synthesis of high-entropy carbide nanoparticles for tetracycline degradation via persulfate activation

The development of high-entropy carbide nanoparticles merits untold scientific and technological potential,yet their synthesis remains a challenge using conventional synthetic techniques.Herein we present a facile,rapid and low-cost route for the combustion synthesis of(Ta_(0.25)Nb_(0.25)-Zr_(0.25)Ti_(0.25))C high-entropy carbide(HEC-1)nanoparticles by self-propagating reaction of metal oxides,carbon and Mg mixture precursors in NaF salt media for the first time.The combustion synthesis possibility of HEC-1 is first analyzed theoretically from thermodynamic aspects,and then the ultrafine HEC-1 nanoparticles(average particle size:~19 nm)are synthesized successfully by the combustion synthesis technique at combustion temperature of~1487 K,duration of 63 s,and heating rate of~68 K s^(-1).The as-synthesized HEC-1 nanoparticles possess high compositional uniformity and low oxygen impurity content of 2.98 wt%.To prove their utility,the as-synthesized HEC-1 nanoparticles are utilized as an effective persulfate activation catalyst for the degradation of tetracycline pollutant in groundwater or wastewater and a removal efficiency of~65.5%for tetracycline is obtained after10 h.

Syntheses,characterization and calculations of LimAnM6O15(A=Rb,Cs;M=Si,Ge;m+n=6)

Alike phosphates,silicates and germanates exclusively containing tetrahedral basic building units(BBUs)can also exhibit ultraviolet(UV)even deep-UV transitions.They are important for the design of new UV or deep-UV nonlinear optical(NLO)materials.In this paper,four new alkali metal silicates and germanates,Li2Rb4Si6O15,Li2Cs4Si6O15,Li3Rb3Ge6O15 and Li3Cs3Ge6O15 were successfully synthesized by a high temperature solid state reaction.They obey the general formula of LimAnM6O15(A=Rb,Cs;M=Si,Ge;m+n=6)and all exhibit the Sr2Be2B2O7(SBBO)-like structures.More importantly,Li3Rb3Ge6O15 and Li3Cs3Ge6O15 crystallize in the noncentrosymmetric(NCS)structures and exhibit remarkable phase-matched second harmonic generation(SHG)effect,0.8×KH2PO4(KDP)and 1×KDP,respectively.These indicate that they are potential as UV or deep-UV NLO materials.Furthermore,their optical and NLO properties as well as thermal properties were measured.The structure-property relationships were studied by the dipole moment calculations and the first-principles calculations.

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.

高熵二硼化物纳米颗粒的组分设计与催化降解抗生素研究

开发高熵硼化物材料的功能特性对于拓宽其在极端环境中的潜在应用至关重要.为此,本文通过调控材料的组分开发出具有高效催化性能的高熵二硼化物(HEB_(2))纳米颗粒:首先基于对HEB_(2)的尺寸差异因子、混合焓以及体系自蔓延燃烧模式的理论分析,我们采用一种简便、快速、低成本的燃烧合成方法合成了6种不同组分的HEB_(2)纳米颗粒;然后,通过对材料的组分进行调控实现了HEB_(2)纳米颗粒活化过硫酸盐降解抗生素的高效催化能力(四环素的最高去除效率可达93.5%).不同吸附位点的吸附能和差分电荷密度的第一性原理计算结果进一步证实了HEB_(2)优异的催化性能主要归因于Ti组元,而非高熵效应.此外,基于检测到的活性氧和计算的反应能垒,我们提出了HEB_(2)活化过硫酸盐降解抗生素的潜在催化机理.本研究不仅为HEB_(2)高效催化降解抗生素的组分设计提供了理论依据,而且显示出HEB_(2)在去除自然水体中新污染物方面的潜在应用前景.

Recent advances in F-containing iodate nonlinear optical materials

Metal iodates containing I(Ⅴ)with lone electron pairs in an asymmetric coordination geometry exhibit excellent second-harmonic generation(SHG)responses,wide transmission range and large band gaps.During the past ten years,metal iodates have been widely studied,and introducing large electronegative fluorine atoms into metal iodates has also attracted much attention.These F-containing iodates are different from pure iodates in terms of composition,symmetry and transmittance.Especially because oxide-fluoride heterolepic anion groups can exhibit interesting structure-directing properties,e.g.trans-and cis-directing properties,these F-containing iodates also have better structure designability.Therefore,in this review,we will review the research progress of F-containing iodates and address the effect of structure-directing properties of oxide-fluoride anions on the crystal structures of F-containing iodates.Since the valence of the central cations will greatly affect the distortions and configurations of the oxide-fluoride anion groups,these F-containing iodates will be classified and introduced according to the different valences of the central cations.

Thermal stable and ultralow dielectric loss in(Gd_(0.5)Ta_(0.5))_(x)Ti_(1-x)O_(2)giant permittivity ceramics by defect engineering

High dielectric loss and poor temperature stability are the current barriers to the application of dielectric materials.In present work,we synthesized a system of acceptor Gd^(3+)and donor Ta^(5+)co-doped(Gd_(0.5)Ta_(0.5))_(x)Ti_(1-x)O_(2)(GTTOx,x=0,0.01,0.02,0.04,0.06)ceramics to enhance dielectric response.It was found that a colossal permittivity(CP,2.65×10^(4)@1 kHz,2.37×10^(4)@1 MHz),a very low dielectric loss(tanδ,0.007@1 kHz,0.03@1 MHz),good stability of frequency(20–10^(6)Hz)and temperature(RT–250°C,Δε′(T)/ε′30<±15%,at 1 kHz)were achieved simultaneously in GTTO0.01 ceramic.Complex impedance spectroscopy,XPS,SEM,and Raman spectroscopy were used to investigate the reasons for the improved dielectric properties.The result indicated that the main reasons for CP and low dielectric loss are the synergistic effect of the electron pinning defect-dipole(EPDD)model,the internal blocking layer capacitance(IBLC)mechanism,and electrode response.This work provides a promising approach for the design of defect-related high-performance giant dielectric ceramics.

Effective warm white-light emission with Dy:YAlO3single crystal

Dysprosium-doped orthorhombic yttrium aluminate(Dy:YAlO3or Dy:YAP)single crystals were grown by the Czochralski method with a size ofΦ43 mm×150 mm.Based on the measurements of spectra and theoretical analysis,the white-light emission was investigated with different doping concentrations.The optimal white emission was achieved at Dy^(3+)doping concentration of 1.0%under 450 nm excitation.Combining with residual pumping light,the white-light output was successfully obtained with Commission Internationale de l'Eclairage(CIE)coordinates x=0.3797,y=0.3685,the color temperature of 4000 K,and the largest fluorescence quantum yield of 46.9%.With the development of the GaN laser diode,the Dy:YAP single crystal has proven applicable in white-light-emitting diodes.

Ba(SO_(3)CH_(3))-(2):A Deep-Ultraviolet Transparent Crystal with Excellent Optical Nonlinearity Based on a New Polar Non-π-Conjugated NLO Building Unit SO_(3)CH_(3)^(−)

In this study,the first methyl sulfonate deepultraviolet(DUV)nonlinear optical(NLO)crystal,Ba(SO_(3)CH_(3))_(2),was successfully synthesized with the polar non-π-conjugated tetrahedron,SO_(3)CH_(3)^(−),as a novel DUV NLO building unit.Results showed that Ba(SO_(3)CH_(3))_(2)not only had a very short absorption edge of 159 nm,which is the shortest among reported phase-matchable sulfates or sulfonates,but also exhibited excellent optical properties.(Powder X-ray diffractionwas ca.1.5×KH_(2)PO_(4)and birefringence was 0.04 at 589.3 nm.)It also exhibited high thermal stability and remarkable stability against air and moisture.Additionally,bulk Ba(SO_(3)CH_(3))_(2)crystal could be obtained conveniently from a simple solution evaporation process.Therefore,Ba(SO_(3)CH_(3))_(2)should have great potential as a DUV NLO crystal in the near future.

Ultra-stable carbon-coated sodium vanadium phosphate as cathode material for sodium-ion battery

Based on the excellent sodium ion mobility of sodium superionic conductor structures,Na_(3)V_(2)(PO_(4))_(3)materials have become promising cathode materials in sodium-ion batteries(SIBs).However,inadequate electronic transport of Na_(3)V_(2)(PO_(4))_(3)limits the cycling stability and rate performances in SIBs.In this work,high-performance conductive carbon-coated Na_(3)V_(2)(PO_(4))_(3)materials are obtained via a simple and facile ball-milling assisted solid-state method by utilizing citric acid as carbon sources.The carbon-coated composite electrodes display a high initial specific capacity of 111.6 mAh·g^(-1),and the specific capacity could retention reach 92.83%after 100 cycles at 1C with the high coulombic efficiency(99.95%).More importantly,the capacity of conductive carbon-coated nano-sized Na_(3)V_(2)(PO_(4))_(3)can remain 48.5 mAh·g^(-1) at 10℃after 3000 cycles(initial capacity of 101.2 mAh·g^(-1)).At the same time,high coulombic efficiency(near 100%)has little decay even at a high rate of 20℃during 1000 cycles,demonstrating the excellent cycling stability and remarkable rate performances,and showing potential in largescale productions and applications.

BaYOBO_(3):A deep-ultraviolet rare-earth oxy-borate with a large second harmonic generation response

Deep-ultraviolet(UV)nonlinear optical(NLO)crystals with excellent performances are of great importance in laser science and technology.However,to design and synthesize an ideal deep-UV NLO material with a balance between second harmonic generation(SHG)response and UV cut-off edge is still a huge challenge.Herein,a new oxy-borate BaYOBO_(3)(BaYBO)was designed and synthesized by substituting Be^(2+)with Y^(3+)from Sr_(2)Be_(2)B_(2(O_(7).The BaYBO features a stable three-dimensional framework and satisfies the property balance between a large SHG response(~2.6×KH_(2)PO_(4)KDP))and a short UV cut-off edge(<190 nm)as a promising deep-UV NLO candidate.The study of structure-property relationship indicates that the large SHG response of BaYBO is mainly attributed to the coplanar arrangement and large number density of BO_(3 )triangles.These results demonstrate that substituting Be^(2+)with Y^(3+)cations is also a feasible strategy for developing new deep-UV NLO crystals.

Broadband 1T-polytype tantalum disulfide saturable absorber for solid-state bulk lasers

1T-polytype tantalum disulfide(1T-TaS_(2)),an emerging strongly correlated material,features a narrow bandgap of 0.2 e V,bridging the gap between zero-bandgap graphene and large-bandgap 2D nonlinear optical(NLO)materials.Combined with its intense light absorption,high carrier concentration,and high mobility,1T-TaS_(2) shows considerable potential for applications in broadband optoelectronic devices.However,its NLO characteristics and related applications have rarely been explored.Here,1T-TaS_(2) nanosheets are prepared by chemical vapor deposition.The ultrafast carrier dynamics in the 400–1100 nm range and broadband NLO performance in the 515–2500 nm range are systematically studied using femtosecond lasers.An obvious saturable absorption phenomenon is observed in the visible to IR range.The nonlinear absorption coefficient is measured to be-22.60±0.52 cm MW-1under 1030 nm,which is larger than that of other typical 2D saturable absorber(SA)materials(graphene,black phosphorus,and MoS_(2))under similar experimental conditions.Based on these findings,using 1T-TaS_(2) as a new SA,passively Q-switched laser operations are successfully performed at 1.06,1.34,and 1.94μm.The results highlight the promise of 1T-TaS_(2) for broadband optical modulators and provide a potential candidate material system for mid-IR nonlinear optical applications.