Dy-doped Lu2SiO5 single crystal: spectroscopic characteristics and luminescence dynamics

Spectroscopic and kinetics properties of Lu₂SiO₅:Dy³⁺ (LSO:Dy) single crystal with 1 and 5 at.% of activator were investigated. The polarised absorption and unpolarised emission spectra were measured at 10–300 K. Parameters characterising radiative relaxations of LSO:Dy were estimated by the Judd–Ofelt model. The crystal-field energy structure was derived from low-temperature optical spectra exhibiting the presence of two non-equivalent Dy³⁺ sites. It was found that dysprosium ions in site 1 and in site 2 do not form isolated subsystems; these subsystems are coupled by an effective spectral energy migration process. The LSO:Dy crystal exhibits a strong luminescence in the visible. Strong ion–ion interactions were observed for LSO:Dy (5 at.%); luminescence decays are non-exponential and the macro-parameter of donor–acceptor interaction C _da amounts to 5.3 (10^?52 m⁶?s^?1) and 7.8 (10^?52 m⁶?s^?1) at 10 and 300 K, respectively. Laser potential related to the ⁴F_9/2→⁶H_13/2 yellow luminescence in Dy:LSO was assessed based on evaluation of the emission cross section values. It was concluded that the crystal is a promising material for visible laser operation.     

Fluorescence characteristics of Dy ions in calcium fluoroborate glasses

Calcium fluoroborate (CFB) glasses doped with different concentrations of trivalent dysprosium ions were prepared and investigated by the FTIR, optical absorption, photoluminescence and decay analysis. Free-ion Hamiltonian model and Judd-Ofelt theory have been used to analyze the energy level scheme and the spectral intensities of Dy³⁺ ions in CFB glasses. From the emission spectra it is observed that the samples emit intense light yellowish color which is nearer to white light. Chromaticity color coordinates have been calculated and the dominant emission wavelength has also been indicated. Decay curves of ⁴F_9/2 level for the samples with different concentrations have been analyzed using the Inokuti-Hirayama model and the energy transfer and non-radiative decay rates have been determined.     

VUV-UV excited luminescent properties of LnCa4O(BO3)3:RE (Ln=Y, La, Gd; Re=Eu, Tb, Dy, Ce)

Calcium lanthanide oxyborate doped with rare-earth ions LnCa₄O(BO₃)₃:RE³⁺ (LnCOB:RE, Ln=Y, La, Gd, RE=Eu, Tb, Dy, Ce) was synthesized by the method of solid-state reaction at high temperature. Their fluorescent spectra were measured from vacuum ultraviolet (VUV) to visible region at room temperature. Their excitation spectra all have a broadband center at about 188 nm, which is ascribed to host absorption. Using Dorenbos’ and Jφrgensen's work [P. Dorenbos, J. Lumin. 91 (2000) 91, R. Resfeld, C.K. Jφrgensen, Lasers and Excite States of Rare Earth [M], Springer, Berlin, 1977, p. 45], the position of the lowest 5d levels E(Ln,A) and charge transfer band E_ct were calculated and compared with their excitation spectra.Eu³⁺ and Tb³⁺ ions doped into LnCOB show efficient luminescence under VUV and UV irradiation. In this system, Ce³⁺ ions do not show efficient luminescence and quench the luminescence of Tb³⁺ ions when Tb³⁺ and Ce³⁺ ions are co-doped into LnCOB. GdCOB doped with Dy³⁺ shows yellowish white light under irradiation of 254 nm light for the reason that Gd³⁺ ions transfer the energy from itself to Dy³⁺. Because of the existence of Gd³⁺, the samples of GdCOB:RE³⁺ show higher excitation efficiency than LaCOB:RE³⁺ and YCOB:RE³⁺, around 188 nm, which indicates that the Gd³⁺ ions have an effect on the host absorption and can transfer the excitation energy to the luminescent center such as Tb³⁺, Dy³⁺ and Eu³⁺.     

不同形貌的LaPO4：Dy荧光粉的制备及其真空紫外激发下的发光性能

在水热法中通过改变磷源以及反应溶剂成功合成出了不同形貌的LaPO₄：Dy荧光粉,考察了真空紫外激发下不同形貌的LaPO₄：Dy荧光粉的发光性能.结果表明,由于采用的磷源不同,不同形貌的LaPO₄：Dy荧光粉的发光强度会受到影响;其次颗粒尺寸的大小也会影响发光强度.而形貌对Dy³⁺离子占据的格位的对称性影响不大,三种形貌的LaPO₄：Dy荧光粉的黄蓝比都在1—1.5之间.从激发光谱的对比中可知LaPO₄基质向Dy³⁺离子传递能量的效率不如向其他稀土离子,如Eu³⁺离子的效率高,同时在激发光谱中还观察到了较强的Dy³⁺离子的f-d跃迁激发峰. 关键词： 3+')" href="#">Dy³⁺ 真空紫外 发光     

Laser spectroscopy of Nd and Dy ions in lead borate glasses

The spectroscopic and laser properties of Nd³⁺ and Dy³⁺ ions in lead borate glass were studied. Luminescence spectra recorded in the near-infrared and visible ranges correspond to ⁴F_3/2-⁴I_J/2 (J=9, 11, 13) transitions of Nd³⁺ and ⁴F_9/2-⁶H_J/2 (J=11, 13, 15) transitions of Dy³⁺, respectively. Luminescence decay curves were analyzed as a function of activator concentration. Luminescence quenching is observed, which is due to Ln-Ln interaction increasing. Several spectroscopic parameters relevant to laser potential of Ln³⁺ ions (Ln=Nd, Dy) in lead borate glass were determined. The relatively large values of the quantum efficiency and the room-temperature emission cross-section for the ⁴F_3/2-⁴I_11/2 transition of Nd³⁺ at 1061 nm and the ⁴F_9/2-⁶H_13/2 transition of Dy³⁺ at 573 nm imply that Ln-doped lead borate glasses can be considered as promising solid-state materials for laser applications.     

Luminescence studies on SrMgAl10O17:Eu, Dy phosphor crystals

Using urea as fuel, SrMgAl₁₀O₁₇:Eu, Dy phosphor was prepared by a combustion method. Its luminescence properties under ultraviolet (UV) excitation were investigated. Pure SrMgAl₁₀O₁₇ phase was formed by urea-nitrate solution combustion synthesis at 550 °C. The results indicated that the emission spectra of SrMgAl₁₀O₁₇:Eu, Dy has one main peak at 460 nm and one shoulder peak near 516 nm, which are ascribed to two different types of luminescent Eu²⁺ centers existing in the SrMgAl₁₀O₁₇ matrix crystal. The blue luminescence emission of SrMgAl₁₀O₁₇:Eu phosphors was improved under UV excitation by codoping Dy³⁺ ions. The SrMgAl₁₀O₁₇:Eu phosphors showed green afterglow (λ=516 nm) when Dy³⁺ ions were doped. Dy³⁺ ions not only successfully play the role of sensitizer for energy transfer in the system, but also act as trap levels and capture the free holes in the spinel blocks.     

Single-Ion Mechanism of Weak Ferromagnetism and a Spin-Flop Transition in One- and Two-Position Antiferromagnets

Nuclear resonance reflectivity from a [Dy₁₉Gd₁₉] × 20 superlattice has been measured utilizing the 25.652 keV nuclear level of ¹⁶¹Dy. The measured time spectra of nuclear resonance reflectivity make it possible to reveal the variation of the hyperfine magnetic field B_hf on dysprosium nuclei in the temperature range of 4–110 K and to determine the relaxation time of the hyperfine field, using the decay speed-up of the excited state of ¹⁶¹Dy nuclei.     

Luminescence of KCaSO4Cl:X, Y (X=Eu or Ce; Y=Dy or Mn) halosulfate material

Polycrystalline KCaSO₄Cl:Eu, Dy, KCaSO₄Cl:Ce, Dy and KCaSO₄Cl:Ce, Mn phosphors prepared by a solid state diffusion method have been studied for its photoluminescence (PL) characteristics. The presence of two overlapping bands at around 400 and 450 nm in the PL emission spectra of the phosphor suggests the presence of Eu²⁺ in the host compound occupying two different lattice sites. The effects of co-doping on the photoluminescence (PL) characteristics of KCaSO₄Cl:Eu or Ce phosphors have been studied. The decrease in peak intensity of the phosphor on co-doping it with Dy gives an insight into the emission mechanism of the phosphors, which involves energy transfer from Eu²⁺→Dy³⁺, Ce³⁺→Dy³⁺ and Ce³⁺→Mn²⁺.     

Visible luminescence properties of Er3+–Dy3+ codoped tellurite glasses

Er³⁺ and Dy³⁺ codoped tellurite glasses have been synthesized. Five emission bands in the PL spectrum under 325 nm pumping were observed. Three of them correspond to Er³⁺ and the other two correspond to Dy³⁺, respectively. The PL spectrum revealed that the intensity of Dy³⁺ characteristic emission was enhanced as Er³⁺ concentration increased while keeping Dy³⁺ concentration constant. Due to small mismatch between the energy level of Er³⁺:⁴F_7/2 and Dy³⁺:⁴F_9/2 resonant energy was possibly transferred between them. This process can give rise to an enhancement of the PL intensity of 484 and 574 nm from Dy³⁺. The PL spectra of these glasses cover the blue, green and red wavelength range and the intensities of those emission bands could be controlled by adjusting the concentration of relevant rare-earth ions. These glasses with the controllable CIE coordinates might be a potential candidate for the widely realistic application such as solid-state white lighting and multicolor display.     

Optical amplification properties of Dy3+-doped Gd2SiO4, Lu2SiO5 and YAl3(BO3)4 single crystals

Comparative investigation of the optical amplification properties of dysprosium doped Gd₂SiO₅, Lu₂SiO₅ and YAl₃(BO₃)₄ single crystals was performed in a pump-and-probe experiment. High power laser pulses at 475 nm were used as the pump source in order to strongly populate the ⁴F_9/2 level of the Dy³⁺ ions due to ground state absorption. Low signal beam cw radiation at 574 nm was used as the probe beam to stimulate the emission associated with the ⁴F_9/2→⁶H_13/2 electronic transition of the Dy³⁺ ions. The process was modelled as a three levels system, and their populations were analysed and simulated in order to study the gain dynamics. Positive optical gain was observed and compared in these crystals. These results confirmed that among the systems studied the Dy³⁺-doped YAl₃(BO₃)₄ single crystal can be considered as a good candidate to develop an optical amplifier employing the ⁴F_9/2→⁶H_13/2 transition at around 574 nm which is the first step to consider as laser active media.     

掺稀土元素Dy和Mn,P,Cu的MgSO4的热释发光光谱

实验测定了MgSO₄:Dy,Mn和MgSO₄:Dy,P以及MgSO₄:Dy,P ,Cu等的热释光磷光体的三维发光谱.结果表明,掺入Dy的MgSO₄磷光体的热释发 光谱线的波长与Dy³⁺离子的能级跃迁相关,Dy³⁺为热释光主要发光 中心.MgSO₄中只掺入Mn时,温度在140℃和190℃附近呈现波长为660nm宽范围的 连续发光带,这是Mn形成的发光中心的 关键词： 热释发光光谱 稀土元素镝 硫酸镁     

Luminescent properties of Dy doped SrMoO4 phosphor

Trivalent dysprosium ions (Dy³⁺) doped strontium molybdate (SrMoO₄) phosphors were synthesized by solid-state reaction and their photoluminescence (PL) properties were investigated. X-ray powder diffraction (XRD) analysis confirmed the formation of SrMoO₄:Dy³⁺. PL measurements indicated that the phosphor exhibited intense emission at 482, 490 (⁴F_9/2→⁶H_15/2) and 575 nm (⁴F_9/2→⁶H_13/2) under UV excitation. The effect of the doping concentration of Dy³⁺in SrMoO₄:Dy³⁺ on the PL was investigated in detail. Na⁺ ion was a good charge compensator for SrMoO₄:Dy³⁺.     

Luminescence and time-resolved spectroscopy properties of (Gd1−xEux)(BO2)3 multicrystals

(Gd_1?xEu_x)(BO₂)₃ (0≤x≤1) phosphors are synthesized by traditional high temperature solid state reaction. The photoluminescence (PL) properties of Gd(BO₂)₃ and Gd(BO₂)₃ activated with Eu³⁺ are investigated. The PL spectra exhibit the typical characteristic emission and excitation of Gd³⁺ and Eu³⁺ ions, and support the energy transfer taking place from Gd³⁺ to Eu³⁺ ions. The relationship between Eu³⁺ doping concentration and emission intensity is also studied. Even if all of the Gd³⁺ ions are substituted by Eu³⁺ ions, the concentration quenching between Eu³⁺ happens. However, the quenching is not complete. The luminescence decay curves are measured, and the lifetimes become short with the Eu³⁺ content increasing. The decreasing Gd³⁺ lifetimes also indicates that there exists efficient energy transfer between Gd³⁺ and Eu³⁺ ions.     

Dy含量对红色长余辉发光材料Sr3Al2Ｏ6:Eu2＋,Dy3＋性能的影响

采用溶胶凝胶法制备了Sr₃Al₂Ｏ₆:Eu^2＋,Dy^3＋红色长余辉发光材料,利用X射线衍射仪对材料的物相进行了分析,结果表明,1200℃下制备的样品的物相为Sr₃Al₂Ｏ₆,少量的Eu和Dy掺杂没有影响样品的相组成.采用荧光分光光度计、照度计测定了样品的发光特性.结果表明Sr₃Al₂Ｏ关键词： 红色长余辉 3Al₂Ｏ₆')" href="#">Sr₃Al₂Ｏ₆ 溶胶凝胶法     

Hyperfine interactions and crystal field effects in intermetallic compounds between Dy and 3d transition metals

A model based on the relative strengths of the magnetic exchange and electric field interactions is proposed for explaining the differences observed between the ¹⁶¹Dy Mössbauer spectrum of Dy₂Ni₁₇ where two dysprosium sites are observed and spectra of Dy₂Fe₁₇ and Dy₂Co₁₇ which show only one hyperfine pattern.     

Electron paramagnetic resonance of Gd3+ ions in Ca1 − x − y Y x Gd y F2 + x + y crystals

Electron paramagnetic resonance of Ca_{1 ? x ? y} Y _x Gd _y F_{2 + x + y} single crystals has revealed spectra that are not typical of gadolinium-doped CaF₂ crystals. These spectra have a nearly tetragonal symmetry and are most probably caused by Gd³⁺ ions localized in yttrium clusters. Weak spectra of tetragonal Gd³⁺ centers, whose parameters are close to those of a cubic gadolinium center caused by an isolated Gd³⁺ ion, have been also detected. These centers are attributed to isolated Gd³⁺ ions localized near octahedral rare-earth clusters or their associations.     

苯甲酸-镝-钇配合物的发光

合成了苯甲酸-镝-钇固体配合物并研究了它们的光致发光性质.实验结果表明,当苯甲酸镝中部分Dy3+离子被Y3+离子取代时,可以便配合物中Dy3+离子的发光增强.     

Influences of Doping and Annealing on the Structural and Photoluminescence Properties of Y2O3 Nanophosphors

This paper reports the structural and optical properties of rare earth doped and codoped yttrium oxide nanophosphors. Dysprosium (Dy³⁺) and Terbium (Tb³⁺) doped and codoped yttrium oxide (Y₂O₃) phosphors were prepared by combustion synthesis method and subsequently annealed to high temperature to eliminate the hydroxyl group (?OH) and to get more crystallinity. The formation of compounds was confirmed by the X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR). The diffuse reflectance spectra (DRS) of doped and codoped Y₂O₃ powder phosphors were measured and it is observed that the absorption edge of the doped samples is shifted towards blue region with respect to undoped sample. The bandgap of the prepared samples were evaluated with the help of Kubelka-Munk function using Diffuse Reflectance Spectra (DRS) and an increase in bandgap was observed with the decrease in crystallite size. A strong characteristics emission from Tb³⁺ and Dy³⁺ ions was identified and the influence of doping concentration and annealing temperature on photoluminescence properties was systematically studied. Transfer of energy was observed in dysprosium–terbium codoped Y₂O₃ nanophosphor at room temperature from Dy³⁺ ions toTb³⁺ ions.     

Electron paramagnetic resonance of Dy3+ ions in lead thiogallate single crystals

The results of electron paramagnetic resonance (EPR) studies of Dy³⁺ ions in lead thiogallate PbGa₂S₄ single crystals have been presented. It has been shown that the ground state of these ions corresponds to the lowest Stark sublevel Γ₆ of the term ⁶ H _15/2. The spectra are well described by the axially symmetric spin Hamiltonian with the effective spin S = 1/2 with the factors g _‖ = 15.06 and g _⊥ = 2.47. The Dy³⁺ ions substitute Pb²⁺ ions in the crystal lattice of PbGa₂S₄. The observed hyperfine structure has allowed to unambiguously interpret the EPR spectra. The hyperfine interaction constants of two odd isotopes of dysprosium in lead thiogallate single crystals have been found to be A _‖ = 675 × 10^?4 cm^?1 and A _⊥ = 111 × 10^?4 cm^?1 for ¹⁶³Dy and A _‖ = 472 × 10^?4 cm^?1 and A _⊥ = 77 × 10^?4 cm^?1 for ¹⁶¹Dy.     

Spectroscopic and photoluminescence characteristics of Dy ions in lead containing sodium fluoroborate glasses for laser materials

Lead containing calcium zinc sodium fluoroborate (LCZSFB) glasses doped with different concentrations of trivalent dysprosium ions were prepared and investigated by the XRD, FTIR, optical absorption, photoluminescence and decay curve analysis. The experimentally determined oscillator strengths have been determined by measuring the areas under the absorption peaks and the Judd–Ofelt (J–O) intensity parameters were calculated using the least squares fit method. From the evaluated J–O parameters the radiative transition probability rates, radiative lifetimes and branching ratios were calculated for ⁴F_9/2 excited level. Room temperature photoluminescence spectra for different concentrations of Dy³⁺-doped LCZSFB glasses were obtained by exciting the glass samples at 386 nm. The intensity of Dy³⁺ emission spectra increases with increasing concentration of 0.1, 0.25, 0.5 and 1.0 mol% and beyond 1.0 mol% the concentration quenching is observed. The measuring branching ratios are reasonably high for transitions ⁴F_9/2→⁶H_15/2 and ⁶H_13/2, suggesting that the emission at 484 and 576 nm, respectively, can give rise to lasing action in the visible region. From the visible emission spectra, yellow–blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The lifetimes of ⁴F_9/2 metastable state for the samples with different concentrations were also measured and discussed.