A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and s...A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and structural characteristics of both the BAGO host lattice and the Eu^(2+)ions activated BAGO phosphors were investigated through field-emission scanning electron microscopy and X-ray diffractometry analyses,respectively.The BAGO host lattice has micro-sized particles and the Rietveld refinement reveals the presence of a monoclinic crystal phase,characterized by the space group I2/c(No.15).Introducing Eu^(2+)ions into Ba^(2+)sites under CO condition reduces the particle size,switching from microscale to nanoscale.Within the near-ultraviolet spectrum(353 nm),the BAGO:xEu^(2+)phosphors exhibit a broadband bluish-green photoluminescence(PL)emission characterized by a peak band at 492 nm.This phenomenon is attributed to the 4f^(6)5d^(1)→4f^(7) electronic transition.The BAGO:0.02Eu^(2+)phosphor shows the strongest bluish-green PL emission,and a co mprehensive description of the concentration quenching mechanism between Eu^(2+)ions is revealed.Additionally,the thermal stability of the optimized BAGO:0.02Eu^(2+)phosphor was investigated,and its activation energy was estimated.Therefore,the synthesized bluish-green BAGO:0.02Eu^(2+)phosphor holds the promise of being a novel and potential candidate for utilization in white light-emitting diode applications.展开更多
Ba2Co9O14(BCO)是一种新型的电子-氧离子混合导体,在氧离子导体的固体氧化物燃料电池(SOFC)中,其作为阴极材料的应用可能性已经得到证实,本工作探索BCO在质子导体SOFC中的应用可能性。采用固相反应法制备BCO粉体,研究BCO与质子导体电解...Ba2Co9O14(BCO)是一种新型的电子-氧离子混合导体,在氧离子导体的固体氧化物燃料电池(SOFC)中,其作为阴极材料的应用可能性已经得到证实,本工作探索BCO在质子导体SOFC中的应用可能性。采用固相反应法制备BCO粉体,研究BCO与质子导体电解质BZCY(Ba Zr0.1Ce0.7Y0.2O3-δ)之间的化学相容性,分析BCO-BZCY复合阴极在BZCY电解质上的电化学性能。当复合阴极中BCO的质量含量为70%时,阴极性能最佳,界面阻抗活化能为1.26 e V。以BCO-BZCY为阴极,Ni-BZCY为阳极,BZCY为电解质的阳极支撑型单电池,700℃时,单电池的极化阻抗为0.15Ω·cm2,最大功率密度为400 m W·cm-2。展开更多
Ultrasmall near-monodisperse Ba2ErF7 nanocrystals with average crystal size 9.6 nm were synthesized with solvothermal method. The X-ray diffraction （XRD） and transmission electron microscopy （TEM） assays reveal th...Ultrasmall near-monodisperse Ba2ErF7 nanocrystals with average crystal size 9.6 nm were synthesized with solvothermal method. The X-ray diffraction （XRD） and transmission electron microscopy （TEM） assays reveal that the as-synthesized Ba2ErF7 nanocrystals are of the cubic structure with the cell parameter of 5.943 A, instead of the reported orthorhombic and tetragonal structure. Two emission bands originated from 2Hwj4H3/2 → 4F5/2 and 4F9/2 ----＋ 4115,2 of Er3＋ can be observed under a 980 nm laser excitation. The magnetic mass susceptibility of the as-synthesized BazErF7 nanocrystals reaches 4.293 × 10-5 emu g-1 Oe-1.展开更多
Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n＋4. The direct information on the Cu ion site at the atomic level is ...Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n＋4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu（1）-O bond is 0.561, and the average covalency of Cu（2）-O is 0.296. Mossbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu （1） site in forms of Fe^3＋ and Fe^4＋; for higher doping, Fe^3＋ and Fe^4＋ ion occupies Cu（1） and Cu（2） site respectively. The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by MSssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.展开更多
White light-emitting diodes(WLEDs)fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting.The crystallographic site occupation of activators in a proper host lattice is cru...White light-emitting diodes(WLEDs)fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting.The crystallographic site occupation of activators in a proper host lattice is crucial for sophisticated design of such phosphor.Here,we report a high quality white lightemitting phosphor Ba_(2)Ca(BO_(3))_(2):Ce^(3+)(K^(+)),Eu^(2+),Mn^(2+)with spectral distribution covering whole visible region.Blue light emission originates from Ce3+ions occupying preferentially Ba^(2+)site by controlling synthesis conditions.Green and red lights are obtained from Eu^(2+)occupying Ba2+(and Ca)site and Mn2+occupying Casite,respectively.In this triple-doped phosphor,strong red emission with a low concentration of Mn2+is realized by the efficient energy transfer from Ce3+and Euto Mn.Furthermore,high quality white light is accomplished by properly tuning the relative doping amount of Ce^(3+)(K^(+))/Eu^(2+)/Mn^(2+)based on efficient simultaneous energy transfer.The results indicate that Ba_(2)Ca(BO_(3))_(2):Ce^(3+)(K^(+)),Eu^(2+),Mn^(2+)is a promising white light-emitting phosphor in WLEDs application.展开更多
A new barium aluminoborate, Ba2Al4B6O17, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601...A new barium aluminoborate, Ba2Al4B6O17, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601(5), b = 9.1835(6), c = 10.6574(7) ?, a = 95.050(6)°, b = 111.569(5)°, g = 90.280(6)°, V = 811.71(9) ?3, Z = 2, Mr = 719.46, Dc = 2.944 g/cm3, μ = 5.127 mm-1, F(000) = 660, R = 0.0361 and wR = 0.0855 for 3846 observed reflections and 262 variables. This compound represents a new structure that features a three-dimensional [Al4B6O17]n4n- framework constructed by AlO4 tetrahedra, BO3 triangles, and B2O54-groups composed of two corner-sharing BO3 triangles, with intersecting open channels accommodating Ba2+ cations. It melts incongruently at 849 ℃. The existence of BO3 groups is confirmed by FT-IR and Raman spectra. The insulating nature with an optical band gap of about 3.50 eV is revealed by UV-VIS diffuse reflectance spectrum. Band structure calculations indicate that it is an indirect band material.展开更多
基金Project supported by the National Research Foundation of Korea Grant funded by the Korean government(MSIP)(2018R1A6A1A03025708)。
文摘A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and structural characteristics of both the BAGO host lattice and the Eu^(2+)ions activated BAGO phosphors were investigated through field-emission scanning electron microscopy and X-ray diffractometry analyses,respectively.The BAGO host lattice has micro-sized particles and the Rietveld refinement reveals the presence of a monoclinic crystal phase,characterized by the space group I2/c(No.15).Introducing Eu^(2+)ions into Ba^(2+)sites under CO condition reduces the particle size,switching from microscale to nanoscale.Within the near-ultraviolet spectrum(353 nm),the BAGO:xEu^(2+)phosphors exhibit a broadband bluish-green photoluminescence(PL)emission characterized by a peak band at 492 nm.This phenomenon is attributed to the 4f^(6)5d^(1)→4f^(7) electronic transition.The BAGO:0.02Eu^(2+)phosphor shows the strongest bluish-green PL emission,and a co mprehensive description of the concentration quenching mechanism between Eu^(2+)ions is revealed.Additionally,the thermal stability of the optimized BAGO:0.02Eu^(2+)phosphor was investigated,and its activation energy was estimated.Therefore,the synthesized bluish-green BAGO:0.02Eu^(2+)phosphor holds the promise of being a novel and potential candidate for utilization in white light-emitting diode applications.
文摘目的:制备高效稳定的分子筛,以满足高原地区和特殊地区的用氧需求。方法:采用离子交换改性法来提高分子筛的吸附能力。以应用广泛的4A型分子筛为原料,制备Ca2+、Ba2+交换改性的分子筛材料,并通过X射线衍射(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、红外光谱(infrared spectroscopy,IR)和BET(Brunner-Emmet-Teller)分析测试,观察分子筛的晶体结构和孔结构,得出Ba2+交换改性的特点。结果:Ca2+和Ba2+作为平衡阳离子能够交换到4A型分子筛中,经过Ca2+和Ba2+交换后分子筛比表面积增大,且分子筛仍为典型的微孔分子筛,孔体积变化不大。结论:该研究为制氧吸附剂性能的提高提供了新思路,为进一步研发高性能的制氧分子筛材料奠定了基础。
基金The Science and Technology Innovative Research Team of Zhejiang Province(2009R50010)The Zhejiang Science and Technology Innovation Projects for students(2009R409014)
文摘Ba2Co9O14(BCO)是一种新型的电子-氧离子混合导体,在氧离子导体的固体氧化物燃料电池(SOFC)中,其作为阴极材料的应用可能性已经得到证实,本工作探索BCO在质子导体SOFC中的应用可能性。采用固相反应法制备BCO粉体,研究BCO与质子导体电解质BZCY(Ba Zr0.1Ce0.7Y0.2O3-δ)之间的化学相容性,分析BCO-BZCY复合阴极在BZCY电解质上的电化学性能。当复合阴极中BCO的质量含量为70%时,阴极性能最佳,界面阻抗活化能为1.26 e V。以BCO-BZCY为阴极,Ni-BZCY为阳极,BZCY为电解质的阳极支撑型单电池,700℃时,单电池的极化阻抗为0.15Ω·cm2,最大功率密度为400 m W·cm-2。
文摘Ultrasmall near-monodisperse Ba2ErF7 nanocrystals with average crystal size 9.6 nm were synthesized with solvothermal method. The X-ray diffraction （XRD） and transmission electron microscopy （TEM） assays reveal that the as-synthesized Ba2ErF7 nanocrystals are of the cubic structure with the cell parameter of 5.943 A, instead of the reported orthorhombic and tetragonal structure. Two emission bands originated from 2Hwj4H3/2 → 4F5/2 and 4F9/2 ----＋ 4115,2 of Er3＋ can be observed under a 980 nm laser excitation. The magnetic mass susceptibility of the as-synthesized BazErF7 nanocrystals reaches 4.293 × 10-5 emu g-1 Oe-1.
文摘Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n＋4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu（1）-O bond is 0.561, and the average covalency of Cu（2）-O is 0.296. Mossbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu （1） site in forms of Fe^3＋ and Fe^4＋; for higher doping, Fe^3＋ and Fe^4＋ ion occupies Cu（1） and Cu（2） site respectively. The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by MSssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.
基金Project supported by the National Key Research and Development Plan of China(2019YFE0107200)the Natural Science Foundation of Hubei Province(2020CFB700)+4 种基金the Doctoral Researchof Hubei University of Arts and Science(kyqdf2020023)Innovation Research Team Project of Hubei University of Arts and Science(2020kypytd001)the Project of Hubei University of Arts and Science(XK2021027)the National Natural Science Foundation of China(10804099)Natural Science Foundation of Zhejiang Province(LZ18B050002)。
文摘White light-emitting diodes(WLEDs)fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting.The crystallographic site occupation of activators in a proper host lattice is crucial for sophisticated design of such phosphor.Here,we report a high quality white lightemitting phosphor Ba_(2)Ca(BO_(3))_(2):Ce^(3+)(K^(+)),Eu^(2+),Mn^(2+)with spectral distribution covering whole visible region.Blue light emission originates from Ce3+ions occupying preferentially Ba^(2+)site by controlling synthesis conditions.Green and red lights are obtained from Eu^(2+)occupying Ba2+(and Ca)site and Mn2+occupying Casite,respectively.In this triple-doped phosphor,strong red emission with a low concentration of Mn2+is realized by the efficient energy transfer from Ce3+and Euto Mn.Furthermore,high quality white light is accomplished by properly tuning the relative doping amount of Ce^(3+)(K^(+))/Eu^(2+)/Mn^(2+)based on efficient simultaneous energy transfer.The results indicate that Ba_(2)Ca(BO_(3))_(2):Ce^(3+)(K^(+)),Eu^(2+),Mn^(2+)is a promising white light-emitting phosphor in WLEDs application.
基金Supported by the National Natural Science Foundation of China(No.20871012)
文摘A new barium aluminoborate, Ba2Al4B6O17, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601(5), b = 9.1835(6), c = 10.6574(7) ?, a = 95.050(6)°, b = 111.569(5)°, g = 90.280(6)°, V = 811.71(9) ?3, Z = 2, Mr = 719.46, Dc = 2.944 g/cm3, μ = 5.127 mm-1, F(000) = 660, R = 0.0361 and wR = 0.0855 for 3846 observed reflections and 262 variables. This compound represents a new structure that features a three-dimensional [Al4B6O17]n4n- framework constructed by AlO4 tetrahedra, BO3 triangles, and B2O54-groups composed of two corner-sharing BO3 triangles, with intersecting open channels accommodating Ba2+ cations. It melts incongruently at 849 ℃. The existence of BO3 groups is confirmed by FT-IR and Raman spectra. The insulating nature with an optical band gap of about 3.50 eV is revealed by UV-VIS diffuse reflectance spectrum. Band structure calculations indicate that it is an indirect band material.
