The primary purpose of this work is to optimize the thermophysical properties of rare-earth tan-talate ceramics using the high-entropy effect.Here,the high-entropy rare-earth tantalate ceramic(Y_(0.1)Nd_(0.1)Sm_(0.1)G...The primary purpose of this work is to optimize the thermophysical properties of rare-earth tan-talate ceramics using the high-entropy effect.Here,the high-entropy rare-earth tantalate ceramic(Y_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Dy_(0.1)Ho_(0.1)Er_(0.1)Tm_(0.1)Yb_(0.1)Lu_(0.1))TaO_(4)((10RE_(0.1))TaO_(4))is synthesized successfully.The lat-tice distortion and oxygen vacancy concentration are characterized firstly in the rare-earth tantalates.Notably,compared with single rare-earth tantalates,the thermal conductivity of(10RE_(0.1))TaO_(4) is reduced by 16%-45%at 100℃ and 22%-45%at 800℃,and it also presents lower phonon thermal conductivity in the entire temperature range from 100 to 1200℃.The phonon thermal conductivity(1.0-2.2 W m^(-1) K^(-1),100-1200℃)of(10RE_(0.1))TaO_(4) is lower than that of the currently reported high-entropy four-,five-and six-component rare-earth tantalates.This is the result of scattering by the ferroelastic domain,lattice distortion associated with size and mass disorder,and point defects,which target low-,mid-and high-frequency phonons.Furthermore,(10RE_(0.1))TaO_(4),as an improved candidate for thermal barrier coatings materials(TBCs),has a higher thermal expansion coefficient(10.5×10^(-6)K^(-1) at 1400℃),lower Young’s modulus(123 GPa)and better high-temperature phase stability than that of single rare-earth tantalates.展开更多
Two novel phosphors LiBa_(4(1-x))Eu_(4x)Ta_(3)O_(12)(H-LBTO:xEu^(3+)) and Li_(0.25)Ba_(1-x)Eu_(x)Ta_(0.75)O_(3)(C-LBTO:xEu^(3+))were prepared successfully by a molten salt method.The transformation between these two s...Two novel phosphors LiBa_(4(1-x))Eu_(4x)Ta_(3)O_(12)(H-LBTO:xEu^(3+)) and Li_(0.25)Ba_(1-x)Eu_(x)Ta_(0.75)O_(3)(C-LBTO:xEu^(3+))were prepared successfully by a molten salt method.The transformation between these two structures was realized by changing the sintering temperature or changing the Eu^(3+) ions concentration,which was also demonstrated by the X-ray diffraction(XRD),scanning electron microscopy(SEM),diffuse reflectance spectra(DRS),and photoluminescence excitation(PLE) analyses,Both the sintering temperature and the Eu^(3+)ions doping concentration have significant impact on the formation of the crystal phase.All these phosphors sintered at 1023 K exhibit two major luminescence lines at 594 and 614 nm under nearUV light of 395 nm excitation,corresponding to Eu^(3+)ions typical transitions of ^(5)D_(0)→^(7)F_(1) and ^(5)D_(0)→^(7)F_(2).The optimum concentration of Eu^(3+) ions is 9 mol% for C-LBTO:xEu^(3+) samples and the quenching interaction type is the nearest-neighbor ion interaction.The thermal stability of the C-LBTO:0.09Eu^(3+)sample was investigated in detail and the device application further suggests that C-LBTO:0.09Eu^(3+) can be used as a red phosphor for near-UV excited w-LEDs in lighting.展开更多
A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphol...A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphology,element distribution and luminescent properties of the SLTO:xSm^(3+)(x= 0.01 mol%-0.30 mol%) phosphors were investigated. Under 408 nm excitation, the optimum doped SLTO:0.10Sm^(3+) phosphor emits orangered light at 598 nm with the highest emission peak(4G_(5/2)→6H_(7/2)). The critical energy transfer distance is 1.687 nm. The prepared SLTO:0.10Sm^(3+)phosphor has excellent thermal stability with temperature quenching temperature(T_(0.5)> 500 K) and high activation energy(E_(a)= 0.25 e V). Through calculation, the chromaticity coordinates of all samples are concentrated in the orange-red area, and the color purity reaches 99%. The fabricated white light-emitting diode(w-LED) has a good correlated color temperature(5132 K), a high R_(a)(89), and the CIE chromaticity coordinates(0.340, 0.327). Consequently, the superiority of orange-red-emitting tantalate SLTO:Sm^(3+) phosphors for w-LEDs is demonstrated.展开更多
A set of novel red phosphors Li_(8)CaLa_(2)Ta_(2)O_(13):Eu^(3+)(LCLTO:xEu^(3+))were successfully prepared using a solid-state reaction method.The properties of the prepared samples,including phase purity,elemental com...A set of novel red phosphors Li_(8)CaLa_(2)Ta_(2)O_(13):Eu^(3+)(LCLTO:xEu^(3+))were successfully prepared using a solid-state reaction method.The properties of the prepared samples,including phase purity,elemental composition,and morphology,were systematically investigated using X-ray diffraction,scanning electron microscopy,and diffuse reflectance spectroscopy analyses.The 610 nm maximum emission peak is attributed to the^(5)D_(0)→^(7)F_(2)transition of Eu^(3+)ion under 394 nm irradiation.Among all the LCLTO:xEu^(3+)phosphors,LCLTO:0.6Eu^(3+)showed the strongest emission intensity because of the concentration quenching effect of the electric dipole-dipole in-teraction among the Eu^(3+)ions,which was also demonstrated by the decay curves.Remarkably,the emission intensity of the optimal LCLTO:0.6Eu^(3+)phosphor,which exhibited a high internal quantum efficiency of 49.30%and excellent color purity of 96.79%,was approximately 2.29 times higher than that of commercial Y203:Eu^(3+)red phosphors.The thermal stability of the LCLTO:0.6Eu^(3+)sample with good color stability was meticulously inves-tigated.The fabricated white-light-emitting diode(WLED)exhibited a superior color-rendering index of Ra=82 and chromaticity coordinates of(0.3260,0.3639),suggesting that LCLTO:0.6Eu^(3+)has potential applicability in developing efficient and high-quality WLEDs.Moreover,the prepared LCLTO:0.6Eu^(3+)/PDMS composite film demonstrated exceptional flexural resistance and chemical stability,indicating considerable promise for practical anti-counterfeitingapplications.展开更多
A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a ...A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a sharp emission peak at 612 nm under near-ultraviolet(n-UV) at 395 nm because of the ^(5)D0→^(7)F_(2) transition of Eu^(3+).The optimal Eu^(3+)doping concentration in Ca_(2)YTaO_(6) is 40 mol% and the critical energy-transfer distance of Eu^(3+)ions was calculated to be 0.9 nm.The emission spectra of Ca_(2)YTaO_(6):Eu_(3+)from 300 to 480 K were investigated.The thermal-quenching temperature(T_(0.5)) of Ca_(2)YTaO_(6):Eu^(3+)is above 480 K.The color purity of Ca_(2)YTaO_(6):40 mol%Eu^(3+)is as high as 99.8%.The luminescence lifetime of Ca_(2)YTaO_(6):40 mol%Eu^(3+)was also discussed.The high color purity and high thermal stability of Eu^(3+)-doped Ca_(2)YTaO_(6) phosphors contribute to its application value in white lightemitting diodes(w-LEDs).展开更多
A series of Eu 3+ doped of Mtype of yttrium orthotantalate Y 1-x Eu x TaO 4( x =0-0.30) was sythesized. The influence of activator concentration on luminescence properties was studied in detail. The strong evidence fr...A series of Eu 3+ doped of Mtype of yttrium orthotantalate Y 1-x Eu x TaO 4( x =0-0.30) was sythesized. The influence of activator concentration on luminescence properties was studied in detail. The strong evidence from excitation spectra, emission spectra and diffusive reflection spectra of this system shows that there is energy transfer from TaO 3- 4 to Eu 3+ via the charge transfer and spectral overlap.展开更多
A new tantalate compound KSr 2Ta 3O 10 was synthesized by solid state reaction for the first time in the ternary system K 2O SrO Ta 2O 5, and its single crystals were prepared using flux method. The chemical compositi...A new tantalate compound KSr 2Ta 3O 10 was synthesized by solid state reaction for the first time in the ternary system K 2O SrO Ta 2O 5, and its single crystals were prepared using flux method. The chemical compositions, crystal structure, optical property, density and melting point of the new compound were characterized by EPMA, XRD, DTA and so on. KSr 2Ta 3O 10 crystallizes the orthorhombic system with unit cell parameters a= 0.784 4(1) nm, b =0.777 0(1) nm, c =3.012 7(1) nm and space group P 2 12 12 1, Z =8. The structure may be described as treble perovskite sheets [Sr 2Ta 3O 10 ] - interleaved with K +. Further, it was found that KSr 2Ta 3O 10 has intercalation phenomenon. Na +, Li +, H +, NH + 4 could exchange the interlayer cations K + of KSr 2Ta 3O 10 , and n hexylamine also could intercalate into the place between the layers of [Sr 2Ta 3O 10 ] -. [WT5HZ]展开更多
Electro-optic(EO)crystals are important material for all-solid-state laser technology,which can be used to fabricate various laser modulators,such as EO switches,laser deflectors,and optical waveguide.The improvements...Electro-optic(EO)crystals are important material for all-solid-state laser technology,which can be used to fabricate various laser modulators,such as EO switches,laser deflectors,and optical waveguide.The improvements in new high-efficiency EO crystal materials have held great significance to the development of laser technology.Potassium tantalate niobate(KTN)is a popular multifunctional crystal because of its remarkable and excellent quadratic EO effect.KTN EO modulation technology offers numerous advantages,such as high efficiency,good stability,a quick response time,and inertia-free characteristics.In this paper,we summarize the research progress of KTN series crystals systemically,including the theoretical exploration on quadratic EO effect,solid-melt crystal growth technique,comprehensive physical characterization,new physical effect and mechanisms exploration,new EO devices development and design.The EO modulation technique based on the Kerr effect of KTN series crystal offers obvious advantages in reducing the drive voltage and device size,which could better meet the developmental needs of future lasers with a wide wavelength,miniaturization,and integration.This may provide theoretical guidance and an experimental basis for the design and development of new EO crystal devices and promote the development of laser technology.展开更多
Potassium tantalate niobate （KTa1-xNbxO3, KTN） crystals with different dimensions and quality situations were grown by Czochralski method. Crystal growth process and morphology properties of KTN are presented in thi...Potassium tantalate niobate （KTa1-xNbxO3, KTN） crystals with different dimensions and quality situations were grown by Czochralski method. Crystal growth process and morphology properties of KTN are presented in this paper. It was found that some defects, such as bubble, inclusion, crack, dislocation etc., can all appear if the crystal is grown in an improper condition. The character and formation mechanism of such defects in macro growth are discussed. We consider that the CO2, which was not released absolutely during the sintering process and dissolved in the melt, led to bubbles. The composition of the inclusion caused by high pulling and rotation rates is KTN polycrystalline. The crack and dislocation in KTN crystal mainly come from improper temperature field. Etching and high-resolution X-ray diffraction （HRXRD） experiment results indicate that the central area is the defects concentrated.展开更多
Na2Ta2O6 photocatalyst was prepared by a combination of solid-state reaction with hydrothermal approach. The samples were characterized by XRD, SEM, FT IR, DRS and BET. Powder X-ray diffraction data revealed that it h...Na2Ta2O6 photocatalyst was prepared by a combination of solid-state reaction with hydrothermal approach. The samples were characterized by XRD, SEM, FT IR, DRS and BET. Powder X-ray diffraction data revealed that it had well crystallized, belongs to cubic structure and pure phase. SEM images showed that the photocatalyst were clava with floccule in the middle of it. The band gap of Na2Ta2O6 was estimated to be 4.6 eV from the UV-Vis diffuse reflectance spectra. Under UV-light irradiation, it showed a photocatalytic activity for degradation of Congo Red solution.展开更多
The optical parametric oscillator (OPO) based on the periodically poled lithium tantalate (PPLT) crystal (40 mm×5 mm×1 mm) is fabricated. The OPO is pumped by a Q-switched Nd:YAG laser working at 1.064 μm. ...The optical parametric oscillator (OPO) based on the periodically poled lithium tantalate (PPLT) crystal (40 mm×5 mm×1 mm) is fabricated. The OPO is pumped by a Q-switched Nd:YAG laser working at 1.064 μm. An average idler output power (around 3.8 μm) of 1.2 W and signal output power (around 1.48 μm) of 3 W are obtained when the pump power is 20 W.展开更多
基金financially supported by the Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province(Nos.202102AB080019-1 and 202002AB080001-1)the Yun-nan Fundamental Research Projects(Nos.202101AW070011 and 202101BE070001-015).
文摘The primary purpose of this work is to optimize the thermophysical properties of rare-earth tan-talate ceramics using the high-entropy effect.Here,the high-entropy rare-earth tantalate ceramic(Y_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Dy_(0.1)Ho_(0.1)Er_(0.1)Tm_(0.1)Yb_(0.1)Lu_(0.1))TaO_(4)((10RE_(0.1))TaO_(4))is synthesized successfully.The lat-tice distortion and oxygen vacancy concentration are characterized firstly in the rare-earth tantalates.Notably,compared with single rare-earth tantalates,the thermal conductivity of(10RE_(0.1))TaO_(4) is reduced by 16%-45%at 100℃ and 22%-45%at 800℃,and it also presents lower phonon thermal conductivity in the entire temperature range from 100 to 1200℃.The phonon thermal conductivity(1.0-2.2 W m^(-1) K^(-1),100-1200℃)of(10RE_(0.1))TaO_(4) is lower than that of the currently reported high-entropy four-,five-and six-component rare-earth tantalates.This is the result of scattering by the ferroelastic domain,lattice distortion associated with size and mass disorder,and point defects,which target low-,mid-and high-frequency phonons.Furthermore,(10RE_(0.1))TaO_(4),as an improved candidate for thermal barrier coatings materials(TBCs),has a higher thermal expansion coefficient(10.5×10^(-6)K^(-1) at 1400℃),lower Young’s modulus(123 GPa)and better high-temperature phase stability than that of single rare-earth tantalates.
基金supported by the Foundation of Fujian Provincial Department (2021J011149)。
文摘Two novel phosphors LiBa_(4(1-x))Eu_(4x)Ta_(3)O_(12)(H-LBTO:xEu^(3+)) and Li_(0.25)Ba_(1-x)Eu_(x)Ta_(0.75)O_(3)(C-LBTO:xEu^(3+))were prepared successfully by a molten salt method.The transformation between these two structures was realized by changing the sintering temperature or changing the Eu^(3+) ions concentration,which was also demonstrated by the X-ray diffraction(XRD),scanning electron microscopy(SEM),diffuse reflectance spectra(DRS),and photoluminescence excitation(PLE) analyses,Both the sintering temperature and the Eu^(3+)ions doping concentration have significant impact on the formation of the crystal phase.All these phosphors sintered at 1023 K exhibit two major luminescence lines at 594 and 614 nm under nearUV light of 395 nm excitation,corresponding to Eu^(3+)ions typical transitions of ^(5)D_(0)→^(7)F_(1) and ^(5)D_(0)→^(7)F_(2).The optimum concentration of Eu^(3+) ions is 9 mol% for C-LBTO:xEu^(3+) samples and the quenching interaction type is the nearest-neighbor ion interaction.The thermal stability of the C-LBTO:0.09Eu^(3+)sample was investigated in detail and the device application further suggests that C-LBTO:0.09Eu^(3+) can be used as a red phosphor for near-UV excited w-LEDs in lighting.
基金Project supported by the Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the Key Discipline of the Education Department in Hunan Province(18A465)+1 种基金the Natural Science Foundation of Hunan Province(2023JJ31000)the Natural Science Foundation of Shaanxi Province(2022NY-224)。
文摘A novel layered perovskite tantalate phosphor Sr_(3)LaTa_(3)O_(12):Sm^(3+)(SLTO:Sm^(3+)) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphology,element distribution and luminescent properties of the SLTO:xSm^(3+)(x= 0.01 mol%-0.30 mol%) phosphors were investigated. Under 408 nm excitation, the optimum doped SLTO:0.10Sm^(3+) phosphor emits orangered light at 598 nm with the highest emission peak(4G_(5/2)→6H_(7/2)). The critical energy transfer distance is 1.687 nm. The prepared SLTO:0.10Sm^(3+)phosphor has excellent thermal stability with temperature quenching temperature(T_(0.5)> 500 K) and high activation energy(E_(a)= 0.25 e V). Through calculation, the chromaticity coordinates of all samples are concentrated in the orange-red area, and the color purity reaches 99%. The fabricated white light-emitting diode(w-LED) has a good correlated color temperature(5132 K), a high R_(a)(89), and the CIE chromaticity coordinates(0.340, 0.327). Consequently, the superiority of orange-red-emitting tantalate SLTO:Sm^(3+) phosphors for w-LEDs is demonstrated.
基金supported by the Foundation of Fujian Province(No.2021J011149)the financial support of Innovative Research Team of Ningde Normal University(No.2023T03)Fujian Provincial Department of Education(No.JAT210469).
文摘A set of novel red phosphors Li_(8)CaLa_(2)Ta_(2)O_(13):Eu^(3+)(LCLTO:xEu^(3+))were successfully prepared using a solid-state reaction method.The properties of the prepared samples,including phase purity,elemental composition,and morphology,were systematically investigated using X-ray diffraction,scanning electron microscopy,and diffuse reflectance spectroscopy analyses.The 610 nm maximum emission peak is attributed to the^(5)D_(0)→^(7)F_(2)transition of Eu^(3+)ion under 394 nm irradiation.Among all the LCLTO:xEu^(3+)phosphors,LCLTO:0.6Eu^(3+)showed the strongest emission intensity because of the concentration quenching effect of the electric dipole-dipole in-teraction among the Eu^(3+)ions,which was also demonstrated by the decay curves.Remarkably,the emission intensity of the optimal LCLTO:0.6Eu^(3+)phosphor,which exhibited a high internal quantum efficiency of 49.30%and excellent color purity of 96.79%,was approximately 2.29 times higher than that of commercial Y203:Eu^(3+)red phosphors.The thermal stability of the LCLTO:0.6Eu^(3+)sample with good color stability was meticulously inves-tigated.The fabricated white-light-emitting diode(WLED)exhibited a superior color-rendering index of Ra=82 and chromaticity coordinates of(0.3260,0.3639),suggesting that LCLTO:0.6Eu^(3+)has potential applicability in developing efficient and high-quality WLEDs.Moreover,the prepared LCLTO:0.6Eu^(3+)/PDMS composite film demonstrated exceptional flexural resistance and chemical stability,indicating considerable promise for practical anti-counterfeitingapplications.
基金The work was supported by Undergraduate Innovation Fund of Northwest A&F UniversityChina(201910712069)+3 种基金Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the key discipline in Hunan Provincethe Projects of the Education Department of Hunan Province(No.18A465)Science and Technology Plan Project of Chenzhou City(jsyf2017014)。
文摘A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a sharp emission peak at 612 nm under near-ultraviolet(n-UV) at 395 nm because of the ^(5)D0→^(7)F_(2) transition of Eu^(3+).The optimal Eu^(3+)doping concentration in Ca_(2)YTaO_(6) is 40 mol% and the critical energy-transfer distance of Eu^(3+)ions was calculated to be 0.9 nm.The emission spectra of Ca_(2)YTaO_(6):Eu_(3+)from 300 to 480 K were investigated.The thermal-quenching temperature(T_(0.5)) of Ca_(2)YTaO_(6):Eu^(3+)is above 480 K.The color purity of Ca_(2)YTaO_(6):40 mol%Eu^(3+)is as high as 99.8%.The luminescence lifetime of Ca_(2)YTaO_(6):40 mol%Eu^(3+)was also discussed.The high color purity and high thermal stability of Eu^(3+)-doped Ca_(2)YTaO_(6) phosphors contribute to its application value in white lightemitting diodes(w-LEDs).
文摘A series of Eu 3+ doped of Mtype of yttrium orthotantalate Y 1-x Eu x TaO 4( x =0-0.30) was sythesized. The influence of activator concentration on luminescence properties was studied in detail. The strong evidence from excitation spectra, emission spectra and diffusive reflection spectra of this system shows that there is energy transfer from TaO 3- 4 to Eu 3+ via the charge transfer and spectral overlap.
文摘A new tantalate compound KSr 2Ta 3O 10 was synthesized by solid state reaction for the first time in the ternary system K 2O SrO Ta 2O 5, and its single crystals were prepared using flux method. The chemical compositions, crystal structure, optical property, density and melting point of the new compound were characterized by EPMA, XRD, DTA and so on. KSr 2Ta 3O 10 crystallizes the orthorhombic system with unit cell parameters a= 0.784 4(1) nm, b =0.777 0(1) nm, c =3.012 7(1) nm and space group P 2 12 12 1, Z =8. The structure may be described as treble perovskite sheets [Sr 2Ta 3O 10 ] - interleaved with K +. Further, it was found that KSr 2Ta 3O 10 has intercalation phenomenon. Na +, Li +, H +, NH + 4 could exchange the interlayer cations K + of KSr 2Ta 3O 10 , and n hexylamine also could intercalate into the place between the layers of [Sr 2Ta 3O 10 ] -. [WT5HZ]
基金supported by the National Natural Science Foundation of China(52072189,and 51972179)Natural Science Foundation of Shandong Province(ZR2020KE019 and ZR2020QE041)+3 种基金Science and Technology Program for Young Innovation Team in Colleges and Universities of Shandong Province,China(2019KJA003)Studio for the Leader of Scientific Research in Jinan(2019GXRC059)Major Innovation Project for Integrating Science,Education&Industry of Qilu University of Technology(Shandong Academy of Sciences)(2022PYI015 and 2022JBZ01-07)Innovation Capability Improvement Project for Small and Mediumsized Technology-based Enterprise of Shandong Province,China(2022TSGC1357).
文摘Electro-optic(EO)crystals are important material for all-solid-state laser technology,which can be used to fabricate various laser modulators,such as EO switches,laser deflectors,and optical waveguide.The improvements in new high-efficiency EO crystal materials have held great significance to the development of laser technology.Potassium tantalate niobate(KTN)is a popular multifunctional crystal because of its remarkable and excellent quadratic EO effect.KTN EO modulation technology offers numerous advantages,such as high efficiency,good stability,a quick response time,and inertia-free characteristics.In this paper,we summarize the research progress of KTN series crystals systemically,including the theoretical exploration on quadratic EO effect,solid-melt crystal growth technique,comprehensive physical characterization,new physical effect and mechanisms exploration,new EO devices development and design.The EO modulation technique based on the Kerr effect of KTN series crystal offers obvious advantages in reducing the drive voltage and device size,which could better meet the developmental needs of future lasers with a wide wavelength,miniaturization,and integration.This may provide theoretical guidance and an experimental basis for the design and development of new EO crystal devices and promote the development of laser technology.
文摘Potassium tantalate niobate （KTa1-xNbxO3, KTN） crystals with different dimensions and quality situations were grown by Czochralski method. Crystal growth process and morphology properties of KTN are presented in this paper. It was found that some defects, such as bubble, inclusion, crack, dislocation etc., can all appear if the crystal is grown in an improper condition. The character and formation mechanism of such defects in macro growth are discussed. We consider that the CO2, which was not released absolutely during the sintering process and dissolved in the melt, led to bubbles. The composition of the inclusion caused by high pulling and rotation rates is KTN polycrystalline. The crack and dislocation in KTN crystal mainly come from improper temperature field. Etching and high-resolution X-ray diffraction （HRXRD） experiment results indicate that the central area is the defects concentrated.
文摘Na2Ta2O6 photocatalyst was prepared by a combination of solid-state reaction with hydrothermal approach. The samples were characterized by XRD, SEM, FT IR, DRS and BET. Powder X-ray diffraction data revealed that it had well crystallized, belongs to cubic structure and pure phase. SEM images showed that the photocatalyst were clava with floccule in the middle of it. The band gap of Na2Ta2O6 was estimated to be 4.6 eV from the UV-Vis diffuse reflectance spectra. Under UV-light irradiation, it showed a photocatalytic activity for degradation of Congo Red solution.
基金supported by the National Natural Science Foundation of China (Grant No. 10534020)the National Key Projects for Basic Research of China (Grant No. 2006CB921804)
文摘The optical parametric oscillator (OPO) based on the periodically poled lithium tantalate (PPLT) crystal (40 mm×5 mm×1 mm) is fabricated. The OPO is pumped by a Q-switched Nd:YAG laser working at 1.064 μm. An average idler output power (around 3.8 μm) of 1.2 W and signal output power (around 1.48 μm) of 3 W are obtained when the pump power is 20 W.
