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     

Thermoluminescence of rare earth activated CdSO4, SrSO4 and BaSO4

The thermoluminescence (TL) of rare earth (RE) activated sulfates of Cd, Sr and Ba was studied above room temperature. Many of the phosphors prepared exhibit an extremely bright TL following X-irradiation (most notably with Sm, Eu, Tb, Dy and Tm dopants), having an efficiency comparable to that of the highest sensitivity phosphors available for TL dosimetry, and exhibiting activator-induced glow peaks between 405 and 480°K. In a given lattice, the RE³⁺ ions produce a characteristic glow peak at the same temperature (independent of the particular RE ion), whereas Eu²⁺ produces a single glow peak at a different temperature. A decrease in glow peak temperature with increasing interatomic spacing was observed in the homologous SrSO₄-BaSO₄ system - this shift being most pronounced in the Eu²⁺ -doped materials. TL emission spectra were obtained for trivalent Sm, Tb, Dy and Tm and for divalent Eu in these sulfates (and also in CaSO₄).     

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⁺.     

晶态四硼酸锶中二价镝的发射

在室温下测量了在空气中灼烧掺杂Dy2O3的SrB3O7的发射光谱。观测到了由Dy^3 到Dy^2 氧化态的变化。经优化,当在空气中灼烧温度为650℃时为产生Dy^2 的最佳温度。在457．9nm的激发下测出了两个峰位分别位于550和660nm的宽发射带。我们认为这两个宽发射带是由Dy^2 离子由5d态向4f基态能级（^5I8）跃迁产生的。讨论了几个有益于在这种基质中还原Dy^3 离子的条件。为了实现Dy^3 离子的还原,我们还在Ar/H2(4%)气氛中制备了Dy2O3掺杂的SrB4O7比较了这种样品和在空气中所制备的样品的光学特性。本文还对标专SrB4O7还原性和稳定性的g－因子由Tm^2 的[E0(Tm^3 /Tm^2 =-2.3V]推导出Dy^2 的[E0(Dy^3 /Dy^2 )=-2.6V],但对这种还原过程的局限性尚未确定。     

Thermoluminescence studies of thermally treated CaB4O7:Dy

Borate based thermoluminescence dosimeters (TLD) show high sensitivity and good TL characteristics. One of the promising material amongst the dosimeters is Dy doped CaB₄O₇. Spectrally resolved thermoluminescence of Dy doped CaB₄O₇ shows three glow peaks at about 50 °C, 240 °C and 380 °C, the intensity of the 240 °C glow peak being the maximum. All TL experiments were conducted on a high sensitivity TL spectrometer at Sussex University with a heating rate of 50 °C min^?1. Two main emissions associated with the Dy dopant are observed at ～480 and 580 nm. The samples were subjected to a series of treatments including excitation by X-rays and UV laser radiation. As part of the present research CaB₄O₇:Dy materials were subjected to two different heat treatments; quenching and slow cooling in order to investigate the changes in TL characteristics.     

Influence of Li dopants on thermoluminescence spectra of CaSO4 doped with Dy or Tm

Thermoluminescence emission spectra are presented for lithium doped variants of CaSO₄:Dy or CaSO₄:Tm dosimetry material. All three dopants (Li, Dy and Tm) variously introduce different changes in both the glow peak temperatures and the luminescence efficiency. In every case the emission signals display the line emission characteristic of the rare earth ions. At temperatures below ∼50 K the relative peak intensities differ for Dy and Tm doped samples, and there are small temperature shifts between the Dy:Li and Tm:Li co-doped materials. Above room temperature the rare earth ions do not show peak temperature movements when co-doped with lithium. However they do influence the peak temperature by ∼5 °C when they are the sole dopant. Inclusion of lithium dramatically moves the high temperature glow peak from ∼200 °C down to 120 °C. All these changes are consistent with a single defect model in which the trapping sites and luminescence occur within the complexes formed of the rare earth ion, an intrinsic sulphate defect and lithium. The evidence and rationale for such a model are presented. There is discussion which suggests that such defect complexes are the norm in thermoluminescence.     

Luminescence investigations on sulfate apatite Na6(SO4)2FCl:RE (RE=Dy, Ce or Eu) phosphors

A new phosphor in the Cl-F system doped with Dy, Ce and Eu has been reported. Characterization of this phosphor using XRD, PL and TL techniques is described. Polycrystalline Na₆(SO₄)₂FCl:Dy; Na₆(SO₄)₂FCl:Ce and Na₆(SO₄)₂FCl:Eu phosphors prepared by a solid state diffusion method have been studied for their X-ray diffraction, photoluminescence (PL) and thermoluminescence (TL)characteristics. The PL excitation and emission spectra of phosphors were obtained. Dy³⁺ emission in the host at 475 and 570 nm is observed due to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transition, respectively, whereas the PL emission spectra of Na₆(SO₄)₂FCl:Ce phosphor shows the Ce³⁺ emission at 322 nm due to 5d→4f transition of Ce³⁺ ion. In Na₆(SO₄)₂FCl:Eu lattice, Eu²⁺ as well as Eu³⁺ emissions are observed. The emission of europium ion in this compound exhibits the blue as well as red emission. The TL glow curves of the same compounds have the simple structure with a prominent peak at 150, 175 and 200 °C. TL response, fading, reusability and trapping parameters of the phosphors are also studied. The TL glow curves of γ-irradiated Na₆(SO₄)₂FCl sample show one glow peak indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The trapping parameters associated with the prominent glow peak are calculated using Chen’s half width method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. The intensity of the TL glow peaks increases with increase of the added γ-ray dose to the samples.     

Formation of heavily doped n-type layers in GaAs by multiple ion implantation

Rare earth doping of CaF₂ produces material which gives strong thermoluminescence signals. In an attempt to separate the influence of impurity and intrinsic defects CaF₂ has been implanted with ions of Ce, Dy, Mn, Ca and F. Comparisons are made with chemically doped samples and the effect of thermal treatments have been made in all cases. The cerium and dysprosium ions influence both the shallow charge trapping levels, which determine the temperature of the glow peaks, and the recombination sites which control the photon spectra.

After implantation the strong TL signals show emission at wavelengths near 360 nm for Ce, 480 nm for Dy and for Mn.

Re-excitation of the trapping levels reveals selective emission for some defects, restructuring of less stable defects and major changes in defect concentrations with thermal treatment. The effects of the impurity and intrinsic defects on the spectra are discussed. One major observation is that addition of cerium to “pure” samples does not enhance the TL sensitivity, whereas Dy and Mn both show new glow peaks. In the case of Dy it is thought that the charge trap and the luminescent site are directly linked within one complex defect.     

Thermoluminescence characteristics of Na3 SO4 Cl:X (X=Ce,Dy, Mn) phosphor

In the present paper Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, of Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphor were synthesized by the wet chemical method. Thermoluminescence (TL) characteristics of Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphors were studied for 5 Gy γ-ray dose. In TL glow curve, two peaks have been observed at 129°C and 224°C for different concentrations of Ce and Dy, whereas Mn peaks at 212°C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248°C). A significant single peak is observed in the case of Na₃SO₄Cl:Mn and Na₃SO₄Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h^?1 for 5 Gy γ-rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO₄: Dy for the same γ-rays dose. The paper discuses the preliminary TL characteristics and effect of γ-rays on Na₃SO₄Cl:Ce, Na₃SO₄Cl:Dy, Na₃SO₄Cl:Mn, Na₃SO₄Cl:Ce, Dy and Na₃SO₄Cl:Ce, Mn phosphors.     

Dy或Tb掺杂的MgB4O7磷光体的热释光特性

用高温固相反应法研制了MgB₄O₇:Dy和MgB₄O₇:Tb两种热释光材料.用自制的三维热释光谱仪测量了两种磷光体的三维发光谱,从MgB₄O₇:Dy磷光体的三维发光谱观察到:1.热释光发光峰峰温为220,380℃;2.Dy³⁺离子的发光波长为480,575,660nm;3.220,380℃发光峰的相对强度随高温固相反应温度的升高而变化,但发光峰温和波长基本保持不变.由MgB₄O₇:Tb磷光体的三维发光谱可看到在230,340,420℃附近有三个发光峰,发光谱线波长分别为489,543,589,620nm.不同的高温烧结温度不仅对发光峰的发光强度有很大影响,而且还对Tb³⁺发光谱形产生影响,当温度高于850℃时Tb³⁺离子发光谱线开始变成了发光谱带.此外,对比MgB₄O₇:Dy和MgB₄O₇:Tb两种热释光材料的二、三维发光谱,得出了掺入三价稀土离子的热释光材料的发光峰峰温主要由基质材料决定,发光波长则取决于稀土离子的4f电子能级间的跃迁.     

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     

Photophysical and photoluminescence properties of co-activated ZnS:Cu,Mn phosphors

ZnS:Cu,Mn phosphors were prepared by conventional solid state reaction with the aid of NaCl-MgCl₂ flux at 900 °C. The samples were characterized by X-ray powder diffraction, UV-vis absorbance spectra and photoluminescence spectra. All samples possess cubic structure. Cu has a much stronger effect on the absorption property of ZnS than Mn. Incorporation of Mn into ZnS host only slightly enhances the light absorption, while addition of Cu remarkably increases the ability of absorption due to ground state Cu⁺ absorption. The emission spectra of the ZnS:Cu,Mn phosphors consist of three bands centered at about 452, 520 and 580 nm, respectively. Introduction of Mn significantly quenches the green luminescence of ZnS:Cu. The excitation energy absorbed by Cu is efficiently transferred to Mn activators non-radiatively and the Mn luminescence can be sensitized by Cu behaving as a sensitizer (energy donor).     

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.     

Photoluminescence and thermoluminescence characterization of Eu- and Dy -activated Ca3(PO4)2 phosphor

Rare-earth-doped polycrystalline Ca₃(PO₄)₂:Eu, Ca₃(PO₄)₂:Dy and Ca₃(PO₄)₂:Eu,Dy phosphors prepared by a modified solid-state synthesis has been studied for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) characteristics. The PL emission spectra of the phosphor suggest the presence of Eu³⁺ ion in Ca₃(PO₄)₂:Eu and Dy³⁺ ion in Ca₃(PO₄)₂:Dy lattice sites. The TL glow curve of the Ca₃(PO₄)₂:Eu compounds has a simple structure with a prominent peak at 228 °C, while Ca₃(PO₄)₂:Dy peaking at 146 and 230 °C. TL sensitivity of phosphors are compared with CaSO₄: Dy and found 1.52 and 1.20 times less in Ca₃(PO₄)₂:Eu and Ca₃(PO₄)₂:Dy phosphors, respectively. The Ca₃(PO₄)₂:Eu,Dy phosphors shows switching behavior under two different excitation wavelengths and enhancement in PL intensity of Dy³⁺ ions were reported. The paper discusses the photoluminescence and thermoluminescence behavior of Eu³⁺ and Dy³⁺ ion in Ca₃(PO₄)₂ hosts, it may be applicable to solid-state lighting as well as thermoluminescence dosimetry applications.     

Tm3+单掺杂及Tm3+, Dy3+共掺杂YP1-xVxO4荧光粉的光谱性质

采用共沉淀法制备了Tm³⁺单掺杂及Tm³⁺,Dy³⁺共掺杂的YP_1-xV_xO₄荧光粉材料。给出了样品的XRD谱,获得了样品的SEM照片,对其发射和激发光谱也进行了测量。结果发现,随着钒酸根含量的增加,样品的激发带发生红移,这样的激发带能够满足白光LED用荧光粉的激发要求。在Tm³⁺,Dy³⁺共掺杂的样品中观测到了全色的发射,并且红、绿、蓝三个发射组分的比例也可以调整。我们计算了不同样品的色坐标,发现均在白光范围内,可见该体系样品有希望成为一种全色发射的白光LED用荧光粉。     

Phosphorescent and thermoluminescent properties of SrAl2O4:Eu,Dy phosphors prepared by solid state reaction method

Long persistent SrAl₂O₄:Eu²⁺ phosphors co-doped with Dy³⁺ were prepared by the solid state reaction method. The main diffraction peaks of the monoclinic structure of SrAl₂O₄ were observed in all the samples. The broad band emission spectra at 497 nm for SrAl₂O₄:Eu²⁺, Dy³⁺ were observed and the emission is attributed to the 4f⁶5d¹ to 4f⁷ transition of Eu²⁺ ions. The samples annealed at 1100–1200 °C showed similar broad TL glow curves centered at 120 °C. The similar TL glow curves suggest that the traps responsible for them are similar. The long afterglow displayed by the phosphors annealed at different temperatures, may be attributed to the Dy³⁺ ions acting as the hole trap levels, which play an important role in prolonging the duration of luminescence.     

Dy3+激活无水芒硝在真空紫外光激发下的发光性质

在空气中900℃温度下,将纯天然无水芒硝( Na2 SO4)和DyF3的混合粉末加热25 min,制备了Na2SO4:Dy3+新型发光材料.通过同步辐射研究了NaSO4:Dy3+的发光性质.并测量了在室温中真空紫外-紫外光下的发射和激发光谱.根据发射光谱得到了不同Dy3+掺杂浓度和不同激发下发光的黄蓝比(Y/B)是不同的.通过监测黄色发光得到的激发光谱,分别由Dy3+,4f9→4f85d跃迁(172 nm)、O2--Tm3+之间的电荷转移带(165 nm)引起的强激发谱和基质吸收(138,245 nm)、对应Dy3+,6 H15/2→4 D7/2,6H15/2→6 P3/2,6 H15/2→6P7/2跃迁(299,325,351nm)引起的弱激发谱组成.     

Eu and Ce emission in sulphate based phosphors

Polycrystalline KMgSO₄Cl:Eu and Na₅(PO₄)SO₄:Ce phosphors prepared by a wet chemical method have been studied for its photoluminescence (PL) and thermoluminescence (TL) characteristics. The TL glow curve of the compound has a prominent peak at 200 °C and may be useful for TL study. TL sensitivity of the KMgSO₄Cl:Eu phosphor is found to be 1.7 times less than that of TLD—CaSO₄:Dy. The presence of bands at around 420, 435 and 445 nm in the PL emission spectra of the phosphor suggests the presence of Eu²⁺ in the host compound. Moreover a TL glow curve of the Na₅(PO₄)SO₄:Ce gives a better understanding of the TL mechanism (peaks at 271 and 310 °C) involved in the concerned phosphor. The PL emission spectra are observed at 382 nm for the various concentrations. In this paper we report PL and TL characteristics of KMgSO₄Cl:Eu halosulphate and Na₅(PO₄)SO₄:Ce phosphate sulphate phosphors first time.     

Luminescent properties of Eu2+and Dy3+ ions in Ba4Al2O7 phosphor for solid state lighting

In this paper we report the combustion synthesis of rare earth (RE=Eu, Dy) doped Ba₄Al₂O₇ phosphors. Prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), CIE color co-ordinates and their photoluminescence (PL) properties were also investigated. In case of Ba₄Al₂O₇: Eu²⁺, the emission spectra show unique band centered at 495 nm, which corresponds to the 4f⁶5d¹→4f⁷ transition of Eu²⁺, and PL emission spectra of Dy³⁺ ion under 348 nm excitation give two bands centered at 478 nm (blue) and 575 nm (yellow), which originate from the transitions of ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 of Dy³⁺, respectively. The results indicate that the Eu²⁺ and Dy³⁺ activated Ba₄Al₂O₇ phosphor could find application in solid state lighting.     

Photoluminescence studies of NaCaPO4:RE (RE=Dy, Mn or Gd)

The purpose of the present study is to develop an understanding of photoluminescence properties of Dy³⁺, Mn²⁺ or Gd³⁺doped NaCaPO₄ phosphors, which have served as efficient phosphors in many industrial applications. The phase formation was confirmed by the X-ray powder diffraction (XRD) measurement. Photoluminescence (PL) excitation spectrum measurement of NaCaPO₄:Dy³⁺ shows this phosphor can be efficiently excited by near-ultraviolet (UV) light from 300 to 400 nm and presents dominant luminescence band centered at 480 nm (blue) and 573 nm (yellow). The PL excitation of NaCaPO₄:Mn²⁺ and Gd³⁺ under UV wavelength shows the emissions at 520 and 313 nm, respectively. A scanning electron microscope (SEM) shows an average crystallite size in sub-micrometer range. The obtained results show that the phosphors have the potential for application in the lamp industry and medical applications.