A high intrinsic quality factor （Q0） of a superconducting radio-frequency cavity is beneficial to reducing the oper- ation costs of superconducting accelerators. Nitrogen doping （N-doping） has been demonstrated as...A high intrinsic quality factor （Q0） of a superconducting radio-frequency cavity is beneficial to reducing the oper- ation costs of superconducting accelerators. Nitrogen doping （N-doping） has been demonstrated as a aseful way to improve Q0 of the superconducting cavity in recent years. N-doping researches with 1.3 GHz single cell cavities are carried out at Peking University and the preliminary results are promising. Our recipe is slightly different from other laboratories. After 250μm polishing, high pressure rinsing and 3 h high temperature annealing, the cavities are nitrogen doped at 2.7-4.0Pa for 20rain and then followed by 15μm electropolishing. Vertical test results show that Q0 of a 1.3 GHz single cell cavity made of large grain niobium has increased to 4 ×10 10 at 2.0K and medium gradient.展开更多
Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile...Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2)) is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2) from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2) did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2) catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2) generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.展开更多
Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of pho...Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.展开更多
The establishment of an approach to design tunable yellow emission through singly doped single-phased phosphors to obtain white LED-based InGaN chip was reported. BaY2–xS4：xHo3＋ phosphors were prepared by the high ...The establishment of an approach to design tunable yellow emission through singly doped single-phased phosphors to obtain white LED-based InGaN chip was reported. BaY2–xS4：xHo3＋ phosphors were prepared by the high temperature solid state reaction and characterized by X-ray diffraction and photoluminescence spectra. Under the excitation of 465 nm,the emission spectra of these phosphors exhibited three sharp emission lines peaked at about 492,543 and 661 nm of Ho3＋ corresponding to 5F3,5F4 （5S2） and 5F5→5I8 transitions,respectively,with comparable intensities,resulting in a yellow light emission. The luminescence mechanism for Ho3＋ in BaY2S4 was explained.展开更多
ZnO single crystals were grown by vapor phase reaction of Zno powder with active carbon powdei at an elevated temperature The typical crystals were colorless and transparent with maximum size o4 0.1 mm in diameter and...ZnO single crystals were grown by vapor phase reaction of Zno powder with active carbon powdei at an elevated temperature The typical crystals were colorless and transparent with maximum size o4 0.1 mm in diameter and 25 mm in length, The gas-sensing characteristics of Na+-doped anc undoped single crystals were investigated in 1 %H2. Co and CH, in air between 1 50 and 600℃. It was found that the undoped ZnO single crystals showed little gas sensitivity in air. and Na+-doping can greatly enhance the senstivity by increasing the resistivities. The maximum sensitivity of the samples is 22 (Ra/ Rg) for H2. 1 2 for CO and 4 for CH4展开更多
Benzoyl glycine （BG） is a promising organic nonlinear optical （NLO） crystal, whose second harmonic generation （SHG） efficiency is much higher than that of KDP （potassium dihydrogen phosphate）. Single crystals ...Benzoyl glycine （BG） is a promising organic nonlinear optical （NLO） crystal, whose second harmonic generation （SHG） efficiency is much higher than that of KDP （potassium dihydrogen phosphate）. Single crystals of pure, Cu2＋ and Cd2＋ doped BG were grown by slow evaporation technique. Optically transparent and defect free single crystals of size up to 10 mm×15 mm×10 mm were harvested in a period of 40-60 days. The growth conditions of pure and doped crystals of BG were optimized and the grown crystals were confirmed by single crystal XRD （X-ray diffraction）. The grown crystals were characterized by FTIR （Fourier transform infrared spectroscopy）, optical absorption and microhardness studies. The microhardness studies confirm that BG has a moderate VHN （Vickers hardness number） value in comparison to the.other organic NLO crystals. The efficiency of frequency doubling was measured for the using Nd：YAG laser and the results were discussed.展开更多
Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheet...Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation screening.Due to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and OER.When assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral condition.These results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.展开更多
Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electroche...Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.展开更多
Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials b...Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials by doping with multiple elements,but the preparation method is complicated because a high maximum polarization(P_(max))is sacrificed,which affects the energy storage properties.In this work,we induced antiferroelectric-like relaxor behavior by replacing Bi^(3+)with the single rare-earth ion Pr^(3+)to obtain highly active polar nanoregions(PNRs)that increase the energy storage efficiency(ƞ).In addition,the 6s^(2)lone pair of electrons of Pr^(3+)can produce large ionic displacements similar to those of Bi^(3+).This could maintain the contribution of the A-site polarization to possess large P_(max).Moreover,the high energy gap(E_(g))and reliability increase the breakdown electric field(E_(b)).Consequently,the ultrahigh recoverable energy storage density(Wrec)of 11.01 J/cm^(3)at 552 kV/cm andηof 86.7%are achieved with(Bi_(0.5−x)Pr_(x)Na_(0.5))TiO_(3)component(BPNT-18),which is superior to many other multielement components.It also has fast charging and discharging speeds(t_(0.9)≈37 ns)and high power densities(P_(D)≈312 MW/cm^(3)).This research proposes a simple and effective approach in which a single element is used to obtain excellent energy storage performance in lead-free dielectric ceramics.展开更多
Mid-infrared（MIR） emissions of 2.4 and 3.5 μm from Tm3＋：LiYF4 single crystals attributed to3H4 →3H5 and3H5 →3F4 transitions as well as MIR emissions of 4.2,4.3,and 4.5 μm from Nd3＋：LiYF4 lasers attributed to...Mid-infrared（MIR） emissions of 2.4 and 3.5 μm from Tm3＋：LiYF4 single crystals attributed to3H4 →3H5 and3H5 →3F4 transitions as well as MIR emissions of 4.2,4.3,and 4.5 μm from Nd3＋：LiYF4 lasers attributed to4I15/2 →4I13/2,4I13/2 →4I11/2,and4I11/2 →4I9/2 transitions,respectively,are observed.LiYF4 single crystals possess high transmittance of over 85% in the 2.5-6 μm range.The large emission crosssections of Tm-doped crystals at 2.4 μm（1.9×10-20cm2） and Nd-doped crystals at 4.2 μm（0.84×10-20 cm2） as well as the high rare-earth doping concentrations,excellent optical transmission,and chemicalphysical properties of the resultant samples indicate that Nd3＋and Tm3＋singly doped crystals may be promising materials for application in MIR lasers.展开更多
A highly transparent Eu3＋-doped CaGdA104 （CGA） single crystal is grown by the floating zone method. The segregation coefficient, x ray diffraction, and x ray rocking curve are detected, and the results reveal that ...A highly transparent Eu3＋-doped CaGdA104 （CGA） single crystal is grown by the floating zone method. The segregation coefficient, x ray diffraction, and x ray rocking curve are detected, and the results reveal that the single crystal is of high quality. The f-f transitions of Eu3＋ in the host lattice are discussed. The 5D0-7F2 emis- sion transition at 621 nm （red light） is dominant over the 5D0-7F1 emission transitions at 591 and 599 nm （orange light）, agreeing well with the random crystal environment of Eu3＋ ions in a CGA crystal. The decay time of Eu：5D0 is measured to be 1.02 ms. All the results show that the Eu：CGA crystal has good optical char- acterization and promises to be an excellent red- fluorescence material.展开更多
The X-ray crystal structure of [(dtma)ZnImZn(dtma)]ClO_4·2.5H_2O (Hdtma=4-Diethyl- enetriamineacetic acid) was determined.The crystal is of orthorhombic,space group Pbcn with a- 14.104(5),b=14.897(5),c=25.384(9),...The X-ray crystal structure of [(dtma)ZnImZn(dtma)]ClO_4·2.5H_2O (Hdtma=4-Diethyl- enetriamineacetic acid) was determined.The crystal is of orthorhombic,space group Pbcn with a- 14.104(5),b=14.897(5),c=25.384(9),and Z=8.The least-square refinement of the structure leads to conventional R factor of 0.066.The magnetic properties of [(dtma)CulmZn(dtma)]CIO_4·2.5H_2O were investigated.From the single crystal ESR spectra of Zn—Im—Zn dimer doped with Cu—Im—Zn complex,the anisotropic g and A tensors and electronic spin-density of the Cu—Zn complex are obtained and the bonding nature of Cu is discussed.展开更多
基金Supported by the National Key Program for S&T Research and Development under Grant No 2016YFA0400400the National Natural Science Foundation of China under Grant No 11575012
文摘A high intrinsic quality factor （Q0） of a superconducting radio-frequency cavity is beneficial to reducing the oper- ation costs of superconducting accelerators. Nitrogen doping （N-doping） has been demonstrated as a aseful way to improve Q0 of the superconducting cavity in recent years. N-doping researches with 1.3 GHz single cell cavities are carried out at Peking University and the preliminary results are promising. Our recipe is slightly different from other laboratories. After 250μm polishing, high pressure rinsing and 3 h high temperature annealing, the cavities are nitrogen doped at 2.7-4.0Pa for 20rain and then followed by 15μm electropolishing. Vertical test results show that Q0 of a 1.3 GHz single cell cavity made of large grain niobium has increased to 4 ×10 10 at 2.0K and medium gradient.
文摘Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2)) is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2) from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2) did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2) catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2) generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.
基金financially supported by the National Natural Science Foundation of China (No.52071146)Guangdong Provincial Natural Science Foundation (No.2023A1515010989)the Science and Technology Projects in Guangzhou (No.202201000008)。
文摘Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.
基金Project supported by the National Natural Science Foundation of China (20971042 and 50772035)the Science and Technology Office of Educa-tion Department of Hunan Province (10A070)the Science and Technology Bureau of Changsha City Government (K0902014-11)
文摘The establishment of an approach to design tunable yellow emission through singly doped single-phased phosphors to obtain white LED-based InGaN chip was reported. BaY2–xS4：xHo3＋ phosphors were prepared by the high temperature solid state reaction and characterized by X-ray diffraction and photoluminescence spectra. Under the excitation of 465 nm,the emission spectra of these phosphors exhibited three sharp emission lines peaked at about 492,543 and 661 nm of Ho3＋ corresponding to 5F3,5F4 （5S2） and 5F5→5I8 transitions,respectively,with comparable intensities,resulting in a yellow light emission. The luminescence mechanism for Ho3＋ in BaY2S4 was explained.
文摘ZnO single crystals were grown by vapor phase reaction of Zno powder with active carbon powdei at an elevated temperature The typical crystals were colorless and transparent with maximum size o4 0.1 mm in diameter and 25 mm in length, The gas-sensing characteristics of Na+-doped anc undoped single crystals were investigated in 1 %H2. Co and CH, in air between 1 50 and 600℃. It was found that the undoped ZnO single crystals showed little gas sensitivity in air. and Na+-doping can greatly enhance the senstivity by increasing the resistivities. The maximum sensitivity of the samples is 22 (Ra/ Rg) for H2. 1 2 for CO and 4 for CH4
文摘Benzoyl glycine （BG） is a promising organic nonlinear optical （NLO） crystal, whose second harmonic generation （SHG） efficiency is much higher than that of KDP （potassium dihydrogen phosphate）. Single crystals of pure, Cu2＋ and Cd2＋ doped BG were grown by slow evaporation technique. Optically transparent and defect free single crystals of size up to 10 mm×15 mm×10 mm were harvested in a period of 40-60 days. The growth conditions of pure and doped crystals of BG were optimized and the grown crystals were confirmed by single crystal XRD （X-ray diffraction）. The grown crystals were characterized by FTIR （Fourier transform infrared spectroscopy）, optical absorption and microhardness studies. The microhardness studies confirm that BG has a moderate VHN （Vickers hardness number） value in comparison to the.other organic NLO crystals. The efficiency of frequency doubling was measured for the using Nd：YAG laser and the results were discussed.
基金supported by the Research Funds of Institute of Zhejiang University-Quzhou(IZQ2023RCZX032)the Natural Science Foundation of Guangdong Province(2022A1515010185)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TP-20-005A3)partially supported by the Special Funds for Postdoctoral Research at Tsinghua University(100415017)。
文摘Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation screening.Due to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and OER.When assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral condition.These results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.
基金financially supported by the Natural Science Foundation of Shandong Province (ZR2020QB132,ZR2020MB025)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure (SKL202108SIC)the Taishan Scholar Program of Shandong Province (ts201712046)。
文摘Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.
基金supported by the Key Deployment Projects of the Chinese Academy of Sciences(No.ZDRW-CN-2021-3-1-18)the National Natural Science Foundation of China(No.61475176)+1 种基金the Major Science and Technology Project of Yunnan Province(Nos.202302AB080023 and 202402AC080002)the Special Project for Provincial and Municipal Integration of Yunnan Province(No.202302AH360002).
文摘Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials by doping with multiple elements,but the preparation method is complicated because a high maximum polarization(P_(max))is sacrificed,which affects the energy storage properties.In this work,we induced antiferroelectric-like relaxor behavior by replacing Bi^(3+)with the single rare-earth ion Pr^(3+)to obtain highly active polar nanoregions(PNRs)that increase the energy storage efficiency(ƞ).In addition,the 6s^(2)lone pair of electrons of Pr^(3+)can produce large ionic displacements similar to those of Bi^(3+).This could maintain the contribution of the A-site polarization to possess large P_(max).Moreover,the high energy gap(E_(g))and reliability increase the breakdown electric field(E_(b)).Consequently,the ultrahigh recoverable energy storage density(Wrec)of 11.01 J/cm^(3)at 552 kV/cm andηof 86.7%are achieved with(Bi_(0.5−x)Pr_(x)Na_(0.5))TiO_(3)component(BPNT-18),which is superior to many other multielement components.It also has fast charging and discharging speeds(t_(0.9)≈37 ns)and high power densities(P_(D)≈312 MW/cm^(3)).This research proposes a simple and effective approach in which a single element is used to obtain excellent energy storage performance in lead-free dielectric ceramics.
基金supported by the National Natural Science Foundation of China(Nos.51272109 and 50972061)the Natural Science Foundation of Zhejiang Province(No.R4100364)+1 种基金the Natural Science Foundation of Ningbo City(No.2012A610115)the K.C.Wong Magna Fund in Ningbo University
文摘Mid-infrared（MIR） emissions of 2.4 and 3.5 μm from Tm3＋：LiYF4 single crystals attributed to3H4 →3H5 and3H5 →3F4 transitions as well as MIR emissions of 4.2,4.3,and 4.5 μm from Nd3＋：LiYF4 lasers attributed to4I15/2 →4I13/2,4I13/2 →4I11/2,and4I11/2 →4I9/2 transitions,respectively,are observed.LiYF4 single crystals possess high transmittance of over 85% in the 2.5-6 μm range.The large emission crosssections of Tm-doped crystals at 2.4 μm（1.9×10-20cm2） and Nd-doped crystals at 4.2 μm（0.84×10-20 cm2） as well as the high rare-earth doping concentrations,excellent optical transmission,and chemicalphysical properties of the resultant samples indicate that Nd3＋and Tm3＋singly doped crystals may be promising materials for application in MIR lasers.
基金supported by the Natural Science Foundation of Shanghai under Grant No.15ZR1444700
文摘A highly transparent Eu3＋-doped CaGdA104 （CGA） single crystal is grown by the floating zone method. The segregation coefficient, x ray diffraction, and x ray rocking curve are detected, and the results reveal that the single crystal is of high quality. The f-f transitions of Eu3＋ in the host lattice are discussed. The 5D0-7F2 emis- sion transition at 621 nm （red light） is dominant over the 5D0-7F1 emission transitions at 591 and 599 nm （orange light）, agreeing well with the random crystal environment of Eu3＋ ions in a CGA crystal. The decay time of Eu：5D0 is measured to be 1.02 ms. All the results show that the Eu：CGA crystal has good optical char- acterization and promises to be an excellent red- fluorescence material.
文摘The X-ray crystal structure of [(dtma)ZnImZn(dtma)]ClO_4·2.5H_2O (Hdtma=4-Diethyl- enetriamineacetic acid) was determined.The crystal is of orthorhombic,space group Pbcn with a- 14.104(5),b=14.897(5),c=25.384(9),and Z=8.The least-square refinement of the structure leads to conventional R factor of 0.066.The magnetic properties of [(dtma)CulmZn(dtma)]CIO_4·2.5H_2O were investigated.From the single crystal ESR spectra of Zn—Im—Zn dimer doped with Cu—Im—Zn complex,the anisotropic g and A tensors and electronic spin-density of the Cu—Zn complex are obtained and the bonding nature of Cu is discussed.
