GeO2-Bi2O3-MOx(MOx=WO3,BaO)玻璃近红外超宽带发光的研究

(99.5-χ)GeO2-XBaO-0.5Bi2O3(χ=3,6,9mol%)与(99.5-(4))GeO2-(4)WO3-0.5Bi2O3((4)=3,6,9mol%)玻璃,测定了样品的发射光谱(800 nmLD激发)、吸收光谱、荧光衰减和差热曲线.实验结果表明,在GeO2-.WO3-Bi2O3系统玻璃中,随着WO3含量的增加,在1260 nm处的发光强度增强,荧光半高宽(FWHM)增宽,荧光寿命增长,而且玻璃的吸收边带发生明显的红移;在GeO2-BaO-Bi2O3系统玻璃中,随着BaO含量的增加,玻璃在1290 nm处发光强度增强,FWHM增宽,荧光寿命增长,吸收边带也有明显的红移.从吸收边带发生红移的情况,结合发射光谱和荧光衰减曲线特性,我们推断玻璃样品在近红外的宽带发光可能由Bi5+离子所引起.从荧光特性估算了玻璃的σ×τ和σp×△λ值,这些玻璃均具有较小的σp×τ和较大的σ×△λ特性,说明GeO2-Bi2O3-MOx(MOx=WO3,BaO)系统玻璃是研制成近红外(O到S波段)超宽带光纤放大器的良好材料.     

Bi离子掺杂GeO2-Al2O3-M(M=Na2O，BaO，Y2O3)玻璃的光学性质

用高温熔融法制备了Bi离子掺杂浓度为1mol%的GeO-B₂O₃-Na₂O (GBNB)，GeO₂-Al₂O₃-Na₂O(GANB)，GeO₂-Al₂O₃-BaO(GABB)和GeO₂-Al₂O₃-Y₂O₃(GAYB)玻璃.测定了样品玻璃的差热曲线、吸收、发射光谱及荧光衰减曲线.实验发现GBNB，GANB，GAYB，GABB的吸收边带逐步发生红移.由于这些吸收边带是由Bi³⁺的6s²电子到Bi⁵⁺ 6s⁰空轨道的跃迁引起.因此推断GBNB，GANB，GAYB，GABB玻璃中Bi⁵⁺离子的含量逐步增加.在GABB，GAYB，GANB三个样品中观察到发光中心约1220nm超宽带荧光发射.荧光强度从GABB，GAYB，GANB逐步减弱，荧光半高宽和荧光寿命逐步变小.这些超宽带的荧光归属为Bi⁵⁺离子的发光所致.从吸收与荧光光谱的变化，推断在GeO₂-Al₂O₃玻璃中引入BaO，Y₂O₃组分有利于Bi⁵⁺离子的形成.讨论了BaO，Y₂O₃化学组分对Bi离子在玻璃中的价态影响的内在机理. 关键词： 5+离子')" href="#">Bi⁵⁺离子 超宽带发光 吸收带 荧光寿命     

掺Bi的GeO2-Al2O3-Na2O玻璃的热学和光学性质

用高温熔融法制备了96GeO-(3-χ)Al2O3-χNa2O-1NaBiO3 （将χ分别为0,0.5,1.5的玻璃命名为A1,A2,A3）和 96GeO-(3.5-ψ)Al2O3-ψχNa2O-0.5Bi2O3（将ψ分别为0,0.5,2的玻璃命名为B1,B2,B3）玻璃。观察到样品在1 220 nm处（800 nm 激光二极管激发）的超宽带发光特性（半高宽约250 nm）。结果表明,以NaBiO3形式引入Bi5+到玻璃原料中比以Bi2O3形式引入Bi3+到原料中得到的玻璃在1 220 nm处的发光强度大4.6倍,且荧光寿命和荧光半高宽也分别从280 μs和195 nm增加到了434 μs和275 nm。从A3,A2和A1的吸收边带的红移可初步推断出A3,A2及A1玻璃中Bi5+的含量逐步增加。总结吸收光谱与发射光谱的变化规律,认为Bi离子近红外高发射强度和宽荧光半高宽是由Bi5+的发光引起的。在两组玻璃中,热稳定性以及荧光发射截面积与荧光寿命的乘积值和荧光发射截面积与荧光半高宽的乘积值随着Na2O含量的增加而增加。     

掺Bi的GeO2-Al2O3-Na2O玻璃的热学和光学性质

 用高温熔融法制备了96GeO-(3-χ)Al₂O₃-χNa₂O-1NaBiO₃ （将χ分别为0，0.5，1.5的玻璃命名为A1，A2，A3）和 96GeO-(3.5-ψ)Al₂O₃-ψχNa₂O-0.5Bi₂O₃（将ψ分别为0，0.5，2的玻璃命名为B1，B2，B3）玻璃。观察到样品在1 220 nm处（800 nm 激光二极管激发）的超宽带发光特性（半高宽约250 nm）。结果表明，以NaBiO₃形式引入Bi⁵⁺到玻璃原料中比以Bi₂O₃形式引入Bi³⁺到原料中得到的玻璃在1 220 nm处的发光强度大4.6倍，且荧光寿命和荧光半高宽也分别从280 μs和195 nm增加到了434 μs和275 nm。从A3，A2和A1的吸收边带的红移可初步推断出A3，A2及A1玻璃中Bi5+的含量逐步增加。总结吸收光谱与发射光谱的变化规律，认为Bi离子近红外高发射强度和宽荧光半高宽是由Bi⁵⁺的发光引起的。在两组玻璃中，热稳定性以及荧光发射截面积与荧光寿命的乘积值和荧光发射截面积与荧光半高宽的乘积值随着Na₂O含量的增加而增加。     

Bi2O3-B2O3-BaO玻璃的制备及其近红外发光性能的研究

采用高温熔融法制备了xBi₂O₃-50B₂O₃-(50-x)BaO玻璃, 测定了样品玻璃的近红外光区的发射谱、荧光寿命以及Raman光谱. 在808 nm波长光的激发下, 50Bi₂O₃-50B₂O₃二元玻璃中未观察到近红外发光; 随体系中BaO的加入, 当x为40, 45以及49时, 玻璃样品中观察到了近红外宽带发光现象; BaO含量进一步增加, 当x=10–30时, 近红外发光现象消失; 而当玻璃中Bi浓度很低时, 在0.5Bi₂O₃-50B₂O₃-50BaO及1Bi₂O₃-50B₂O₃-50BaO玻璃中发现了近红外发光现象, 且存在多个发光峰. 对铋离子近红外发光机理进行了初步的探讨.     

Bi离子掺杂GeO2-Al2O3-M(M=Na2O,BaO,Y2O3)玻璃的光学性质

用高温熔融法制备了Bi离子掺杂浓度为1mol%的GeO-B2O3-Na2O (GBNB),GeO2-Al2O3-Na2O(GANB),GeO2-Al2O3-BaO(GABB)和GeO2-Al2O3-Y2O3(GAYB)玻璃.测定了样品玻璃的差热曲线、吸收、发射光谱及荧光衰减曲线.实验发现GBNB,GANB,GAYB,GABB的吸收边带逐步发生红移.由于这些吸收边带是由Bi3+的6s2电子到Bi5+ 6s0空轨道的跃迁引起.因此推断GBNB,GANB,GAYB,GABB玻璃中Bi5+离子的含量逐步增加.在GABB,GAYB,GANB三个样品中观察到发光中心约1220nm超宽带荧光发射.荧光强度从GABB,GAYB,GANB逐步减弱,荧光半高宽和荧光寿命逐步变小.这些超宽带的荧光归属为Bi5+离子的发光所致.从吸收与荧光光谱的变化,推断在GeO2-Al2O3玻璃中引入BaO,Y2O3组分有利于Bi5+离子的形成.讨论了BaO,Y2O3化学组分对Bi离子在玻璃中的价态影响的内在机理.     

铋离子掺杂RO-Al2O3-SiO2玻璃近红外超宽带发光性质

研究了碱土金属氧化物对Bi离子掺杂RO-Al₂O₃-SiO₂ (R=Ca, Sr, Ba)玻璃近红外超宽带发光性质的影响. 结果表明: 玻璃样品在不同抽运源激发下都可检测到较强的近红外超宽带发光. 在808 nm激光激发下, 随着碱土金属离子半径的增加, Bi离子在1 300 nm附近的近红外发光强度显著增加, 荧光半高宽逐渐增加, 其荧光寿命最长可超过600 μms; 而在690 nm激光激发下, 随着碱土金属离子半径的增加, Bi离子在1 100 nm附近的近红外发光呈减弱趋势, 荧光半高宽逐渐增大, 半高宽最大可超过400 nm. 近红外发光可能源于两种不同形式铋的发光中心. 针对上述结果探讨了该玻璃体系中Bi离子近红外发光的机理.     

掺铋离子BaO-B2O3玻璃的制备及其近红外发光性能的研究

采用高温熔融法制备了掺Bi离子的BaO-B₂O₃玻璃, 测定了样品玻璃的近红外以及可见光区的激发、 发射谱、 荧光衰减曲线以及Raman光谱. 在808 nm波长光的激发下, 在掺Bi离子的BaO-B₂O₃玻璃中发现了近红外发光现象, 且存在多个发光峰, 讨论了玻璃网络结构对Bi离子发光的影响, 对其发光机理进行了初步的探讨.     

稀土离子(Eu3+,Tb3+,Ce3+)掺杂ZnAl2O4/SiO2微晶玻璃的制备与发光性能

采用凝胶法分别制备出4.5ZnO-5.5Al₂O₃-90SiO₂(ZAS)以及ZAS[DK]:RE³⁺ (RE=Eu,Tb,Ce) 透明微晶玻璃。利用X射线衍射仪(XRD)、透射电子显微镜(TEM)和荧光光谱仪(PL)等测试手段,研究了稀土离子掺杂浓度对ZAS微晶玻璃的结构和发光性能的影响。XRD结果表明,ZAS[DK]:RE³⁺ (RE=Eu,Tb,Ce)微晶玻璃包含ZnAl₂O₄晶相和SiO₂非晶相,ZnAl₂O₄平均晶粒尺寸约为30 nm,稀土离子的掺杂没有显著改变原来的ZnAl₂O₄晶体结构。TEM结果表明,900 ℃时ZnAl₂O₄从ZAS体系中析出。PL光谱显示,Eu³⁺ 存在 ⁵D₀→⁷F₂跃迁,ZAS[DK]:Eu³⁺在611 nm 处发出强烈的红色光;由于Tb³⁺ 的⁵D₄→⁷F₅ 跃迁,ZAS[DK]:Tb³⁺在541 nm 处发出明亮的绿色光;ZAS[DK]:Ce³⁺ 在381 nm处显示了蓝光发射,对应于Ce³⁺ 的5d→4f 轨道跃迁。ZAS[DK]:RE³⁺ (RE=Eu, Tb, Ce)的PL发射光谱存在着浓度猝灭现象,Eu³⁺、Tb³⁺ 和Ce³⁺的最佳单掺杂摩尔分数分别为20%、20%和3%。CIE色度图表明,ZAS[DK]: RE³⁺ (RE=Eu,Tb,Ce)的色坐标分别位于红光、绿光和蓝光区域。实验结果表明,ZAS:RE³⁺ (RE=Eu,Tb,Ce) 微晶玻璃是一种良好的可用于全色显示的白光LED材料。     

Cr4+掺杂Li1.14Zn1.43SiO4透明微晶玻璃近红外宽带光谱特性

采用高温熔融法和热处理制备了Cr⁴⁺掺杂Li_1.14Zn_1.43SiO₄微晶玻璃, 探讨了不同热处理温度下样品的物相、微观形貌及发光性能. 结果表明: 580℃热处理2h得到的微晶玻璃, Li_1.14Zn_1.43SiO₄微晶的粒径约为5nm, 在808nm的二极管激发下, 可观察到中心波长位于1226nm, 半高宽为230nm的近红外宽带发射峰, 荧光寿命约为200.73±1.71μs. 随着热处理温度的升高, Cr⁴⁺离子所处的晶体场环境发生了变化, 且可以观察到样品吸收光谱发生微弱的蓝移, 而荧光光谱发生少量的红移, 分析了晶体场环境变化对样品发光性能的影响. 关键词： 铬离子 微晶玻璃 超宽带发光 晶体场     

Modification in structural and optical properties of ZnO, CeO2 doped Al2O3-PbO-B2O3 glasses

The structural and optical analysis of glasses is carried out by XRD, FTIR, density and UV visible spectroscopic measurement techniques. XRD results have confirmed the glassy nature of the samples. The FTIR spectral analysis reveals that with the combined presence of ZnO and CeO₂ contents in Al₂O₃-PbO-B₂O₃ glasses, more BO₃ groups are transformed into BO₄. The optical analysis reveals that optical band gap energy decreases more for CeO₂-ZnO-Al₂O₃-PbO-B₂O₃ glasses (from 2.28 to 1.84 eV). The presence of CeO₂ and ZnO in the glass samples causes more compaction of the borate network due to the formation of more BO₄ groups and the presence of ZnO₄ groups, which results an increase in density, refractive index and decrease of molar volume.     

Down-conversion near infrared emission in Pr, Yb co-doped Y2O3 transparent ceramics

Pr³⁺, Yb³⁺ co-doped Y₂O₃ transparent ceramics have been prepared by the solid state reaction and vacuum sintering. Down-conversion near infrared emission has been demonstrated upon a 482 nm excitation. The energy of the 482 nm blue photon was first absorbed by Pr³⁺ and then delivered to Yb³⁺. Possible energy transfer mechanisms from Pr³⁺ to Yb³⁺ have been discussed. Under the 482 nm excitation, the Pr⁴⁺-Yb²⁺ charge transfer state would not seriously influence the energy transfer process. The dominant one should be either the cooperative down-conversion or the two-step photon emission. The efficient down-conversion near infrared emission has potential application in enhancing the conversion efficiency of crystalline silicon solar cells.     

Spectroscopic studies on Pb3O4-ZnO-P2O5 glasses doped with transition metal ions

Optical absorption, Electron Paramagnetic Resonance (EPR) studies are carried out on lead zinc phosphate glass systems doped with Cr³⁺ and VO²⁺. From optical absorption investigations the crystal-field parameters Dq, B and C are evaluated. EPR measurements on Cr³⁺ systems indicate that Cr³⁺ ions are located at sites with low symmetry. EPR spectra of vanadyl doped system revealed the characteristic nature of vanadyl ion. Spin-Hamiltonian and hyperfine values are evaluated for both the systems. Optical absorption spectra of vanadyl doped system revealed three bands that are characteristic of VO(II) ion in tetragonally distorted octahedral site. By correlating both EPR and optical data, the dipolar coupling constant (P) and Fermi-constant coupling parameter (κ) and molecular orbital coefficients β^?2, e_π^?2 are evaluated. Electron Paramagnetic Resonance and optical absorption studies showed that the chemical bonds of Cr³⁺ ions and VO²⁺ ions with the ligands have more covalent nature. From these studies it is also observed that lead spinals are playing major key role in sustaining the covalent nature of bonding.     

Effect of WO3 on structural and optical properties of CeO2-PbO-B2O3 glasses

Pure and WO₃ doped CeO₂-PbO-B₂O₃ glasses are prepared by the melt-quench technique. The structural and optical analyses of glasses are carried out by XRD, FTIR, density and UV-vis spectroscopic measurement techniques. FTIR analysis indicates the transformation of structural units of BO₃ into BO₄ with W-O-W vibration and the presence of WO₄ and WO₆ units observed with increase in WO₃ contents. Decrease in band gap for CeO₂-PbO-B₂O₃ glasses from 2.89 to 2.30 eV and for WO₃ doped glasses from 2.89 to 1.95 eV has been observed and discussed. This decrease in band gap with WO₃ doping approaches to semiconductor behavior. It shows that the presence of WO₃ in the glass samples causes more compaction of the borate network due to the formation of BO₄ groups and the presence of WO₄ and WO₆ groups, which result in a decrease in the optical band gap energy and increase in the density.     

Specific features of photo and thermoluminescence of Tb ions in BaO-M2O3 (M=Ga, Al, In)-P2O5 glasses

BaO-P₂O₅ glasses mixed with the three metal oxides viz., Al₂O₃, Ga₂O₃ and In₂O₃ doped with Tb₂O₃ were prepared. The glasses were characterized by X-ray diffraction and differential thermal analysis. Optical absorption and photoluminescence spectra and thermoluminescence (TL) of these glasses have been studied. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters Ω₂, Ω₄ and Ω₆ have been evaluated and compared with those of other reported glass systems. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of these glasses. From this theory various radiative properties like transition probability A, branching ratio β_r, the radiative lifetime τ_r and the emission cross-section σ^E for various emission levels of these glasses have been determined and reported. An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of all the three glasses. The analysis of TL data indicate high non-radiative losses in In₂O₃ mixed glasses.     

Role of WO3 in structural and optical properties of WO3-Al2O3-PbO-B2O3 glasses

Glass samples of composition xAl₂O₃-20PbO-(80−x)B₂O₃ and xWO₃-xAl₂O₃-20PbO-(80−2x)B₂O₃ with x varying from 0% to 10% mole fraction are prepared by melt quench technique. The optical band gap decreases (from 3.21 to 2.37 eV) more for WO₃-Al₂O₃-PbO-B₂O₃ glasses with an addition of WO₃ content. The FTIR spectral studies have pointed out the conversion of structural units of BO₃ to BO₄ and WO₄ to WO₆ in these glasses. The increase in density from 4.51 to 5.80 g cm⁻³ for WO₃-Al₂O₃-PbO-B₂O₃ glasses is observed with an increase in WO₃ content. This is observed that the atomic structure changes more with the incorporation of WO₃. This is due to the formation of WO₆, WO₄ and BO₄ units.