High Pressure effect on fluorescence lifetime τ for magnetic dipole 5D0→5F1 transitions in YAG:Eu3+

The fluorescence lifetime for magnetic dipole ⁵D₀→⁷F₁ transition in yttrium aluminum garnet doped with Eu³⁺ (YAG:Eu³⁺) crystal was studied under the pressure of up to 10.4?GPa at room temperature. The fluorescence lifetime τ (⁵D₀→⁷F₁ transition) slowly decreased with pressure. The pressure effect on τ (⁵D₀→⁷F₁ transition) was explained with a model which considered pressure effect on line position: inter-ionic distance, ion volume, molecular volume, ion polarizability, molecular polarizability, sample refractive index, and surrounding hydrostatic medium refractive index. The fluorescence lifetime τ calculated by the presented model was in close correspondence with the experimental values.     

Study of the high pressure effect on nanoparticles GdVO4: Eu3+ optical properties

This study considers the effects of hydrostatic pressure on the line position and fluorescence lifetime τ for ⁵D₀ → ⁷F₂ transitions in GdVO₄: Eu³⁺ nanocrystals. The results indicate that the pressure induced the red shift toward longer wavelengths for all the considered lines with different rate. The fluorescence lifetime τ nonlinearly decreases with pressure in the considered pressure range. High pressure induced the fluorescence lifetime τ that can be explained with a simple theoretical model. The measured line position and τ are in a satisfactory agreement with the theoretical calculations.     

High pressure and emission spectra of Eu3+ in L-EuBO3

Effects of the high pressure on the emission spectra of Eu³⁺-activated L-EuBO₃ were considered at room temperature up to 100 kbar. The position of five 0–2 lines in the ⁵D₀→⁷F₂ transition region was determined. The pressure does not have the same effect on all these lines. In four of them, high pressure induced a red shift with different shift rates:+0.0022,+0.0035,+0.0034 and+0.0027 nm kbar^?1, respectively, whereas in the last one, high pressure induced a blue shift with shift rate?0.0034 nm kbar^?1. Possible reasons for the mentioned pressure effects on the line positions were considered.     

Pressure-dependent luminescence properties of Tb3+-doped K–Ba–Al fluorophosphate glass

Tb³⁺-doped fluorophosphate glass with a composition of P₂O₅+K₂O+KF+BaO+Al₂O₃+Tb₄O₇ was prepared by melt quenching technique and characterized through emission spectra and decay curves as a function of pressure up to 37.7 GPa. The ⁵D₄→⁷F₃, ⁷F₄ and ⁷F₅ emission transitions shift toward lower energy in the order of?4.7,?2.4 and?4.0 cm^?1 GPa^?1, respectively, with increasing pressure. A strong increase in the splitting of the ⁵D₄→⁷F₅ Stark levels with pressure is observed. The decay curves for the ⁵D₄ level are found to be almost perfectly single exponential in the entire pressure range studied. Lifetimes of the ⁵D₄ level are found to decrease strongly from 2564 to 886 μs when pressure is increased from ambient to 37.7 GPa. The pressure dependence of all the derived values of the present study is compared with Tb³⁺ in other glasses.     

Influence of high hydrostatic pressure on Eu-luminescence in KMgF3:Eu crystal

Spectroscopic investigations are presented of KMgF₃:Eu²⁺ crystal under high hydrostatic pressure from ambient to 310 kbar. The sample was excited by 30 ps pulses generated by optical parametric generator (OPG) system with wavelength controlled between 210 and 325 nm. The Grüneisen parameters of individual phonons are obtained from the pressure shift of the Eu²⁺ emission related to the ⁶P_7/2→⁸S_7/2 transition accompanied by phonon sideband. The luminescence decays exponentially for the pressure below 135 kbar with lifetime of 3.30 ms and slightly nonexponential above 135 kbar, while the average decay time is nearly independent of the pressure. The results obtained for KMgF₃:Eu²⁺ are compared with those for LiBaF₃:Eu²⁺ in which the ⁶P_7/2→⁸S_7/2 emission is replaced by the broadband emission of the 4f⁶5d¹→4f⁷ transition at high hydrostatic pressure.     

Luminescence of Ca(NbO3)2:Pr at ambient and high hydrostatic pressure

In this contribution, photoluminescence and time-resolved photoluminescence spectra of Ca(NbO₃)₂ doped with Pr³⁺ obtained at high hydrostatic pressure up to 72 kbar applied in a diamond anvil cell are presented. At ambient conditions, the emission spectrum obtained in the time interval 0-1 μs is dominated by spin-allowed transitions from the ³P₀ state. On the other hand, transitions from ¹D₂, characterized by a decay time equal to 30 μs dominate the steady-state luminescence.At pressures lower than 60 kbar, the continuous wave emission spectrum consists of sharp lines peaking between 600 and 625 nm, related to the ¹D₂→³H₄ transition and three lines at 500, 550 and 650 nm related to emission transitions originating from the ³P₀ level of Pr³⁺. The emission from the ¹D₂ excited state depends weakly on the pressure. Its decay time decreases from 33 μs at ambient pressure to less than 22 μs at 68 kbar. On the other hand, the ³P₀ emission is strongly pressure dependent. At pressures of 60 kbar and higher, the Pr³⁺ emission intensity from the ³P₀ state decreases. This is accompanied by a strong shortening of the luminescence decay time.The observed pressure quenching of the f-f emission transitions and the concomitant lifetime shortening have been attributed to increasing crossover from the ³P₀ state of Pr³⁺ to a Pr³⁺-trapped exciton state.     

LnP5O14晶体中Tb3+和Eu3+的发光光谱特性

本工作测量了室温下TbP₃O₁₄和EuP₅O₁₄晶体的吸收和发射光谱。根据吸收光谱和Judd-Ofelt理论计算了Tb³⁺和Eu³⁺的实验和理论的振子强度。用最小二乘法拟合实验与理论的振子强度得到唯象强度参量Ω_λ。然后计算了Tb³⁺的⁵D₃→⁷F₅,⁵D₄→⁷F₄和⁵D₄→⁷F₆以及Eu³⁺的⁵D₀→⁷F₂,⁵D₀→⁷F₄的跃迁几率和寿命。同时用时间分辨光谱测量了不同温度下相应的荧光辐射寿命。计算与实验结果基本相符。理论和实验的结果表明Tb³⁺的⁵D₃态的寿命主要取决于⁵D₃→⁵D₄和⁷F₆→⁷F₀两能级对之间的电偶极-电偶极交叉弛豫。 关键词：     

Effect of pressure and temperature on the wavelength shift of the fluorescence line of SrB 4O 7:Sm 2+ scale

The pressure shift of ⁷D ₀?⁵F ₀ fluorescence line of SrB ₄O ₇:Sm ²⁺ has been recalibrated at high temperature and high pressure, respectively. Combined with the high pressure and high-temperature experimental data given by previous study, a quantitative analysis of the temperature effect on pressure shift of the ⁷D ₀?⁵F ₀ fluorescence line has been performed. The results show that there is an overall negligible coupling effect of temperature and pressure on the wavelength shift of the ⁷D ₀?⁵F ₀ fluorescence line below 770 K and 35 GPa. But above 770 K, the temperature effect on pressure shift could not be ignored at least in a relatively high pressure range. A proposed calibration relation is recommended to predict more accurate pressures in high pressure and high-temperature experiments with SrB ₄O ₇:Sm ²⁺ as the pressure scale.     

SrB4O7:Sm2+: an optical sensor reflecting non-hydrostatic pressure at high-temperature and/or high pressure in a diamond anvil cell

A systematic investigation on the fluorescent spectra of SrB₄O₇:Sm²⁺ was performed in detail at high-temperature up to 623?K and/or high pressure up to 23.2?GPa with different pressure-transmitting media (PTMs), respectively. Combined with experiment data of previous research, the change of the ⁷D₀–⁵F₀ line (0–0 line) full width at half maximum (FWHM) of SrB₄O₇:Sm²⁺ under different pressure environments was specifically discussed. The results indicate that the FWHM of 0–0 line is sensitive to the non-hydrostatic pressure environment in 2-propanol, and methanol and ethanol mixture (ME) PTMs at ambient temperature. The first-order and the second-order derivation of the temperature dependence of 0–0 line FWHM at ambient pressure are 1.48(±0.21)?×?10^?4?nm/K and 9.63(±0.63)?×?10^?7?nm²/K² below 623?K. The 0–0 line FWHM is also sensitive to the non-hydrostatic pressure environment in ME at high-temperature and high pressure simultaneous, the non-hydrostatic transition pressures are 9.6?GPa at 323?K, 11.0?GPa at 373?K, 14.4?GPa at 423?K, respectively. SrB₄O₇:Sm²⁺ is recommended as an optical sensor to reflect the change of pressure environment in liquid media at high-temperature and/or high pressure.     

High-pressure optical studies on R-line fluorescence lifetime in Al2O3:V2+

The effect of high hydrostatic pressure (up to 10.3?GPa) at room temperature on fluorescence lifetime τ for R line (²E→⁴A₂ transition) in ruby Al₂O₃:V²⁺ was studied. The performed studies show the linear increase of τ with increasing pressure. At 10.3?GPa, τ is about 1.36 times higher than at ambient pressure. The obtained trend was explained by a model which considered the effect of pressure on τ through an induced change of line position, inter-ionic distance, compressibility, and molecular polarizability. A good agreement between the calculated and experimental values for τ was obtained.     

Optical Analysis of Er3+:Boro-Fluoro-Phosphate Glasses

This paper deals with the preparation and optical analysis of Er³⁺ (0.2 mol%) boro-fluoro-phosphate glasses in the following glass compositions:

• Series A: 69.8 B₂O₃–10 P₂O₅–10(ZnO/CdO/TeO₂)–10 AlF₃

• Series B: 69.8 B₂O₃–10 P₂O₅–10(ZnO/CdO/TeO₂)–10 LiF

Measured Vis-NIR absorption spectra of Er³⁺:boro-fluoro-phosphate glasses have revealed nine absorption bands at 377 nm, 405 nm, 450 nm, 486 nm, 519 nm, 543 nm, 649 nm, 973 nm and 1529 nm, which correspond with the transitions of ⁴I_15/2 → ⁴G_11/2, (²G_9/2,⁴H_9/2), ⁴F_5/2, ⁴F_7/2, ²H_11/2, ⁴S_3/2, ⁴F_9/2, ⁴I_11/2, and ⁴I_13/2, respectively. With an excitation at λ _exci = 375 nm, a bright green emission (⁴S_3/2 → ⁴I_15/2) at 547 nm has been observed from these erbium glasses. Judd–Ofelt characteristic intensity Ω_λ (λ = 2, 4, 6) parameters are obtained from the absorption spectra, and these results were used to compute the radiative properties of Er³⁺:boro-fluoro-phosphate glasses. The NIR emission (⁴I_13/2 → ⁴I_15/2) at 1547 nm from these glasses was measured with an Ar⁺ laser (514.5 nm) as an excitation source.     

Eu3+-site occupation in CaTiO3 perovskite material at low temperature

In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the un-doped pure CaTiO₃ and Eu³⁺-doped CaTiO₃ samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu³⁺ ions enter into the Ca²⁺ site. The high-resolution photoluminescence spectra of Eu³⁺ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu³⁺ ions occupy only one type of site. Considering the small spectral splitting range of ⁵D₀ → ⁷F₂ transition and the large intensity ratio of ⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁, it can be concluded that Eu³⁺ occupies Ca²⁺ site with larger coordinate numbers rather than Ti⁴⁺ site.     

Synthesis and luminescent properties of nanoparticles GdCaAl3O7:RE (RE=Eu, Tb) via the sol-gel method

By using metal nitrates as starting materials and citric acid as complexing agent, GdCaAl₃O₇:Eu³⁺ and GdCaAl₃O₇:Tb³⁺ powder phosphors were prepared by a citrate-gel method. Thermal analysis (TG-DTG), X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM), photoluminescence excitation and emission, as well as kinetic decays were employed to characterize the resulting samples. The results of the XRD indicated the precursor samples began to crystallize at 800 °C and the crystallinity increased with elevation the annealing temperature. TEM images showed that the phosphor particles were basically of spherical shape, with good dispersion about a particle size of around 40-70 nm. Upon excitation with UV irradiation, it is shown that there is a strong emission at around 617 nm corresponding to the forced electric dipole ⁵D₀-⁷F₂ transition of Eu³⁺, and at around 543 nm corresponding to the ⁵D₄-⁷F₅ transition of Tb³⁺. The dependence of photoluminescence intensity on Eu³⁺ (or Tb³⁺) concentration and annealing temperature were also studied in detail.     

Tm3+离子掺杂的钨酸钇钠晶体中浓度猝灭效应的研究

测量了Tm³⁺离子不同浓度(0.5at.%, 3 at.%, 5 at.%)掺杂的NaY(WO₄)₂晶体在800nm激光二极管激发下的上转换发射光谱.结合吸收谱、荧光谱和由Judd-Ofelt理论计算的光谱参数，详细分析了Tm³⁺:NaY(WO₄)₂晶体中上转换能量传递机理和离子浓度对上转换发射的影响.讨论了四种影响上转换发光效率的离子间相互作用机理：³H₅+¹G₄→³H₆+¹D₂，³H₅+³H₅→³H₆+³F₃，¹G₄+³H₆→³F₄+³F₃，¹G₄+³H₆→³F₃+³F₄，并根据Miyakawa-Dexter理论定量计算了各过程的发生概率.论证了交叉弛豫和共协上转换等浓度猝灭效应是影响Tm³⁺离子蓝色上转换荧光发射效率的主要因素. 关键词： 3+离子')" href="#">Tm³⁺离子 4)₂晶体')" href="#">NaY(WO₄)₂晶体 上转换 浓度猝灭     

Investigation of 515 nm green-light emission for full color emission LaAlO3 phosphor with varied valence Eu

Photoluminescence and lifetime decay properties of varied valence Eu were employed to investigate the luminescence mechanism of green-light emission positioned at ∼515 nm for full color emission LaAlO₃ phosphor co-doped with Eu²⁺ and Eu³⁺. The enhanced ⁵D₂→⁷F₃ transition emission of Eu³⁺ was assigned for this green emission. Energy transfer between Eu²⁺ and ⁵D₂ level of Eu³⁺ was proposed, which results in the enhancement of ⁵D₂→⁷F₃ transition emission. In addition, energy transfer relations between host-Eu and charge transfer state (CTS)-Eu were also discussed associated with the PLE spectra and band schemes.     

Ionic liquid-assisted hydrothermal synthesis of dendrite-like NaY(MoO4)2:Tb phosphor

Micro-sized NaY(MoO₄)₂:Tb³⁺ phosphors with dendritic morphology was synthesized by a ionic liquid-assisted hydrothermal process. X-ray diffraction (XRD) indicated that the as-prepared product is pure tetragonal phase of NaY(MoO₄)₂. Field emission scanning electron microscopy (FE-SEM) images showed that the as-prepared NaY(MoO₄)₂:Tb³⁺ phosphors have dendritic morphology. The photoluminescent (PL) spectra displayed that the as-prepared NaY(MoO₄)₂:Tb³⁺ phosphors show a stronger green emission with main emission wavelength 545 nm corresponding to the ⁵D₄→⁷F₅ transition of Tb³⁺ ion, and the optimal Tb³⁺ doping concentration for obtaining maximum emission intensity was confirmed to be 10 mol%. Based on Van Uitert's and Dexter's models the electric dipole–dipole (D–D) interaction was confirmed to be responsible for the concentration quenching of ⁵D₄ fluorescence of Tb³⁺ in the NaY(MoO₄)₂:Tb³⁺ phosphors. The intrinsic radiative transition lifetime of ⁵D₄ level is found to be 0.703 ms.     

Effect of Eu,Tb codoping on the luminescent properties of Y2O3 nanorods

Red-emitting Y₂O₃:Eu³⁺ and green-emitting Y₂O₃:Tb³⁺ and Y₂O₃:Eu³⁺, Tb³⁺ nanorods were synthesized by hydrothermal method. Their structure and micromorphology have been analyzed by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The photoluminescence (PL) property of Y₂O₃:Eu³⁺,Tb³⁺ phosphor was investigated. In the same host (Y₂O₃), upon excitation with ultraviolet (UV) irradiation, it is shown that there are strong emissions at around 610 and 545 nm corresponding to the forced electric dipole ⁵D₀-⁷F₂ transition of Eu³⁺ and ⁵D₄-⁷F₅ transition of Tb³⁺, respectively. Different qualities of Eu³⁺and Tb³⁺ ions are induced into the Y₂O₃ lattice. From the excitation spectrum, we speculate that there exists energy transfer from Tb³⁺ to Eu³⁺ ions .The emission color of powders reveals regular change in the separation of light emission. These powders can meet with the request of optical display material for different colors or can be potentially used as labels for biological molecules.     

二氧化锆纳米材料中Eu3+的发光特性

研究了掺1mol%Eu³⁺的二氧化锆纳米材料随退火温度变化的发光性质，得到退火温度为600和800℃的样品中Eu³⁺的⁵D₀→⁷F₂发射在604nm处，这种现象不多见. 几种经不同退火温度处理的纳米材料样品在紫外光的照射下，稀土离子Eu³⁺的⁵D₀→⁷F₂发射的发光逐 关键词： 二氧化锆 纳米材料 3+')" href="#">Eu³⁺ 发光     

Effects of electron beam current density and temperature on peak height ratios Dj/D0 for cathodoluminescence of Ln2O2S:Eu

The change in the initial and steady state (∼0 and 5 s after initiation of electron beam irradiation) peak heights from the ⁵D₂⇒⁷F₃, ⁵D₁⇒⁷F₃ and ⁵D₀⇒⁷F₂ cathodoluminescent transitions from Eu³⁺ have been studied for Ln₂O₂S:Eu³⁺ (Ln=La, Gd) phosphors. Specifically, the intensity ratio of these transitions, designated as ⁵D₁/⁵D₀, increased and then decreased for both La₂O₂S:Eu³⁺ (0.1 mole%) and Gd₂O₂S:Eu³⁺ (0.4 mole%), as the current density was changed from 10 towards a 1000 μA/cm². These effects were shown to be consistent with feeding from the higher ⁵D₂ excited state to the lower energy ⁵D₁ excited state, resulting in an increase of the ⁵D₁/⁵D₀ ratio at low current densities. At higher current densities, energy was funneled from the ⁵D₁-⁵D₀ states, resulting in a decrease of the ⁵D₁/⁵D₀ ratio. These effects of feeding versus funneling were dependent on both the Eu³⁺ concentration and current density, and changed with time (i.e., approached a steady state after ∼5 s) due to increased activator interactions from induced internal electric fields. The magnitude of thermal quenching versus interaction quenching was investigated using changes of the peak height ratios of ⁵D₂/⁵D₀ and ⁵D₁/⁵D₀.     

Yb3+:Gd2SiO5晶体的结构和光谱性能

采用提拉法成功生长尺寸为φ30 mm× 75 mm的15at.%Yb³⁺:Gd₂SiO₅单晶, 并用Reitveld全谱拟合方法确定了其晶格常数、原子坐标和温度因子等参数. 用吸收光谱计算了Yb³⁺离子²F_7/2↔ ²F_5/2能级跃迁的振子强度、谱线强度、跃迁概率、 能级寿命和积分发射截面等光谱参数, 并根据激光性能评估得出结论: 表明该晶体具有较大的阈值特性, 有望采用大功率激光二极管泵浦实现可调谐或超快激光输出.