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1.
《稀土》2021,(3)
用共沉淀法制备了Ho~(3+),Yb~(3+)掺杂的β-NaYF_4纳米晶,测量并分析了不同Yb~(3+)掺杂浓度下NaYF_4∶Ho~(3+),Yb~(3+)的荧光光谱与荧光衰减曲线。结果表明,在447 nm泵浦光激发下,较强的近红外光发射主要来源于Ho~(3+)-Yb~(3+)之间高效的能量传递过程。被泵浦光激发的Ho~(3+)通过~5F_4,~5S_2能级与~5F_5能级将能量传递给Yb~(3+),使Yb~(3+)从基态~2F_(7/2)能级跃迁到~2F_(5/2)能级。同时,处于~2F_(5/2)能级的Yb~(3+)可以将能量再传递给Ho~(3+)的~5I_6能级从而增强Ho~(3+)离子~5I_6→~5I_8的跃迁发光。在所研究的样品中,NaYF_4∶3%Ho~(3+),3%Yb~(3+)表现出最强的近红外荧光发射,其980 nm附近的荧光强度是NaYF_4∶3%Ho~(3+)样品的18倍。较强的近红外光发射使得NaYF_4∶Ho~(3+),Yb~(3+)材料在提高太阳能电池的光电转换效率以及进行荧光标记等方面有潜在的应用价值。  相似文献   

2.
In this study,α-TeO_2:Ho~(3+)/Yb~(3+),α-TeO_2:Eu~(3+) and α-TeO_2:Ho~(3+)/Yb~(3+)/Eu~(3+) nanoparticles were prepared via a simple hydrothermal process.The up- and down-conversion properties of the as-prepared nanoparticles were tested at room temperature under a near-infrared photo source(980 nm) and UV-vis photo source,respectively.The results indicated that α-TeO_2 NPs were a kind of outstanding host material for both up- and down-conversion luminescence.The α-TeO_2:Ho~(3+)/Yb~(3+) nanoparticles showed sharp up-conversion emission at 545 and 660 nm under 980 nm excitation,ascribed to the ~5S_2→~5I_8 and ~5F_5→~5I_8(Ho~(3+)) transitions,and weaker down-conversion emission at 545 nm under 455 nm excitation,ascribed to the ~5S_2→~5I_8(Ro~(3+)) transitions.The α-TeO_2:Eu~(3+)nanoparticles showed strong down-conversion emission at 592 and 615 nm under 395 nm excitation,attributed to the ~5D_0→~7F_1 and~5D_0→~7F_2(Eu~(3+)) transitions.Possessing the advantages of these two luminescent materials,the as-prepared tri-doped samples ofα-TeO_2:0.5Ho~(3+)/10Yb~(3+)/3Eu~(3+)(mol.%) nanoparticles could successfully emit visible light via both up- and down-conversion modes.  相似文献   

3.
Ho~(3+) doped La_(2(1–x))Yb_(2x)TiO_5 samples were prepared by sol-gel method. Pyrochlore structured powders were obtained under the annealing of the as-prepared samples at 1100 °C for 3 h in the air. All the samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and photoluminescent spectroscopy. When x=0, we obtained La_2TiO_5 phosphors. Monitored at 546 nm, the excitation spectrum of Ho~(3+) activated La_2TiO_5 phosphors consisted of a broad band originating from the charge-transfer band(CTB) between Ho~(3+) ions and the nearest neighboring O~(2–) ions at 250–280 nm and four sharp bands associated to f-f transitions of Ho~(3+) ions at 350–500 nm. Under the blue light excitation at 461 nm, Ho~(3+) ion in La_2TiO_5 emitted an intense green emission band at 546 nm due to the transition of ~5S_2, ~5F_4→~5I_8. Two intense bands were observed at 490 nm(blue, ~5F_3→I_8) and 663 nm(red, ~5F_5→~5I_8) in the up-conversion(UC) spectrum under 980 nm NIR laser excitation in La_2TiO_5 phosphors activated with Ho~(3+) alone, whereas they were much different from the down-conversion(DC) luminescent samples. When x=7.5 mol.%–17.5 mol.%, the UC emission spectra of them dominated at 546 nm(green, ~5S_2, ~5F_4→~5I_8) and enhanced significantly with the dose of Yb~(3+) ion. The decay curve also confirmed that the transitions of ~5F_4→~5I_8 and ~5S_2→~5I_8 were merged into one emission band at 546 nm.  相似文献   

4.
《中国钨业》2017,(6):60-66
采用高温固相法合成了一系列Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺NaY(MoO_4)_2荧光粉样品。通过X射线衍射仪、扫描电子显微镜、激光粒度仪和荧光光谱仪分别对样品的相纯度、微观形貌、粒径分布和上转换发光性能进行了表征。在980 nm激光激发下,Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺样品的发射光谱中均能观测到中心波长位于536 nm、560 nm的上转换绿光发射和位于660 nm的红光发射,分别归因于Er~(3+)的~2H~(11/2)→~4I_(15/2)、~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→4I_(15/2)能级跃迁。在Er~(3+)单掺体系中共掺Yb~(3+),可以轻松实现由上转换绿光到红光的转变。NaY_(1-x-y)(MoO_4)_2∶x Er~(3+),y Yb~(3+)样品中最优的Er~(3+)/Yb~(3+)掺杂浓度和最佳的烧结温度为x=0.04、y=0.5、T=850℃。基于泵浦依赖和能级图,在Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺体系上转换发光过程中所涉及的能量转移机制被详细讨论。  相似文献   

5.
(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders doped with various concentrations of Tm~(3+) and Ho~(3+) were prepared by the citrate method. The standard cubic Y_2O_3 phase can be matched in the Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2 O_3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm~(3+) to Ho~(3+) and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to ~3 F_4→~3 H_6 transition of Tm~(3+) and ~5 I_7→~5 I_8 transition of Ho~(3+), respectively.Better spectral properties were achieved in Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm~(3+) and 1 mol% Ho~(3+).  相似文献   

6.
本文用水热法合成了YP_5O_(14):Ho~(3+)、Er~(3+)、Tm~(3+)晶体,最大线度为49mm。测定了晶体的紫外可见吸收,激发和荧光光谱。观察到Ho~(3+)离子的~3K_7,Er~(3+)离子的~4G_(11/2)和Tm~(3+)离子的~1D_2能级有强的叠加吸收。用380nm激发,Ho~(3+)离子的~5S_2和Er~(3+)离子的~4S_(3/2)能级绿色荧光(550nm)发射较强,可望是一种绿色发光材料。值得注意的是引入Tm~(3+)离子会强化绿色发射。本文还讨论了Ho~(3+)—Er~(3+)离子间的敏化及Tm~(3+)→Ho~(3+),Er~(3+)离子的能量转移。  相似文献   

7.
采用高温固相法制备了K_2Gd_(1-x-y)(PO_4)(WO_4):x Sm~(3+),y Eu~(3+)新型红色荧光材料,通过利用X射线衍射谱(XRD)、荧光光谱对其结构及发光性能进行了研究。结果表明,稀土离子S~(3+)的掺入没有改变荧光粉的晶相;样品的激发光谱在394 nm有很强的激发峰,与近紫外LED芯片匹配,且Eu~(3+)的~5D_0→~7F_2电偶极跃迁表现出616 nm有较好的红光发射,Eu~(3+)的最佳掺杂量(摩尔分数)为y=0.3;Sm~(3+)进入晶格后,激发峰明显增强和变宽,表明Sm~(3+)对Eu~(3+)的发光起到敏化作用;K_2Gd_(0.68)(PO_4)(WO_4)∶0.3Eu~(3+),0.02Sm~(3+)样品在150℃时发光强度仍为初始温度的78%,具有良好的热稳定性且色纯度高,是一种潜在的白光LED用荧光粉。  相似文献   

8.
采用高温固相反应法制备了一系列Li+掺杂的Ca(W,Mo)O_4∶Eu~(3+)荧光粉。通过X射线衍射仪、扫描电子显微镜及荧光光谱仪对样品的结构、形貌及荧光性能进行了表征。XRD及SEM结果表明,Li~+掺杂没有改变样品原有的四方晶系体心结构,Li+能够以替代和间隙掺杂的方式进入主晶格,适当的Li+掺杂可以改善样品的团聚现象。样品的激发光谱涵盖200~550nm的宽带激发,在395nm激发下,能发射出位于616nm处的窄带红光,归因于Eu~(3+)的~5D_0→~7F_2跃迁,适量Li~+的掺杂明显提升了样品的发光强度。与其他碱金属离子(Na~+、K~+)掺杂相比,Li~+由于半径最小、电负性最强,使得发光强度增强最多。  相似文献   

9.
Intense 1-5 μm infrared emission from near-to mid-infrared was obtained from Ho~(3)+/Yb~(3+)codoped TeO_2-ZnF_2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation,and the emission intensity can be enhanced with the increase of ZnF_2 content.Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra.The stimulated emission cross section of ~5 I6→~5 I_8(1.2 μm),~5 I7→~5 I_8(2.0μm),~5 I_6→~5 I_7(2.85 μm) and ~5 I_5→~5 I_6(4.0 μm) transitions were calculated to reach 0.639 × 10~(-20),0.760 ×10~(-20),0.985×10 20 and 0.484 × 10~(-20) cm~2,respectively.The energy transfer coefficients(C_(DA)) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho~(3+) and Yb~(3+)were figured out.Our results demonstrate that these TeO_2-ZnF_2 glasses,which possess good thermal stability and transparency,low phonon energy(about 600 cm~(-1)),excellent near-and mid-infrared emission in the range of 1-5 μm wavelength,would be promising material for infrared optical fibers and infrared lasers.  相似文献   

10.
《稀土》2017,(2)
通过高温固相法合成了红色荧光粉系列Ba_(1-x)Al_2Si_2O_8:Eu_x~(3+),Li_(0.03)~+,并系统地研究了该系列荧光粉的晶体结构和发光性质的变化。合成的试样均为BaAl_2Si_2O_8晶体,均单斜晶系,空间群为C2/m(12)。Eu~(3+)取代Ba~(2+)格位进入基质BaAl_2Si_2O_8晶体,造成了基质晶胞参数a,b,c和晶胞体积V相应地减小,只引起了基质晶体结构轻微的畸变。试样的激发光谱位于220 nm~550 nm,由一个宽带激发谱和一组锐线峰带构成,激发光谱中的最强峰为393 nm(~7F_0→~5L_6)。通过393 nm波段对系列试样进行有效激发,收集到发射光谱均位于550 nm~750 nm,且由发射光谱中出现多条锐线峰,在614 nm(~5D_0→~7F_2)处发射峰最强,Eu~(3+)的595 nm(~5D_0→~7F_1)发射峰劈裂产生了590 nm、595 nm和599 nm处的三个分裂峰,而614 nm(~5D_0→~7F_2)发射峰劈裂为614 nm、617 nm、619 nm、622 nm和627 nm处的五个分裂峰,Eu~(3+)取代Ba~(2+)进入基质晶格BaAl_2Si_2O_8中,与其临近的氧配体形成了C2的点群对称性和Eu~(3+)主要占据非反演对称中心格位。系统研究了该系列荧光粉发光性能与掺杂离子Eu~(3+)浓度的关联。研究结果显示,当掺杂离子Eu~(3+)浓度x≤0.03时,荧光粉的发光强度随着掺杂离子Eu~(3+)浓度x的增加而增加,当x0.03时,随x的增加而减小。试样的色坐标不随掺杂离子Eu~(3+)浓度改变而改变;该系列荧光粉浓度淬灭机理为电偶极–电偶极相互作用。  相似文献   

11.
《稀土》2020,(4)
为了提高稀土荧光防伪系统的防伪力度,采用沉淀法制备了用于物品安全的Yb~(3+)单掺杂NaYF_4纳米颗粒。利用FT-IR分析了制备过程中间产物的化学组成。利用XRD和TEM对产物的形貌结构进行表征,并结合吸收光谱和发射光谱图,分析了不同掺杂浓度NaYF_4∶Yb~(3+)纳米颗粒发光特性。实验结果表明,Yb~(3+)与苯甲酸钠反应生成了多齿配合物,验证了苯甲酸钠在制备过程中起络合作用。在N_2氛围中经400℃煅烧4 h得到β-NaYF_4∶Yb~(3+)纳米颗粒,平均粒径为86 nm。该纳米颗粒在900 nm光的激发下具有930 nm~1080 nm的不可见红外发射(归属于Yb~(3+)的~2F_(7/2)→~2F_(5/2)),980 nm激发下具有475 nm的蓝色可见发射(归属于Yb~(3+)对的合作上转换发光),最大红外发射和蓝色上转换发射的样品掺杂浓度分别为5%和20%。研究结果表明NaYF_4∶Yb~(3+)纳米颗粒在物品追踪领域具有良好的应用前景。  相似文献   

12.
以DEG为溶剂,分别配置一定比例的GdCl_3, TbCl_3作为前驱液,利用多元醇法合成可用于生物探针的Gd_2O_3:Tb~(3+)纳米晶;将一定量的APTES和TEOS加入制备好的溶液中,使得纳米晶Gd_2O_3:Tb~(3+)的表面包裹聚硅氧烷层。本实验通过马尔文粒度仪、 X射线衍射仪(XRD)、场发射扫描电镜(SEM)、透射电镜(TEM)、荧光分光光度计等检测方法研究不同煅烧温度和不同Tb~(3+)掺杂浓度对纳米晶Gd_2O_3的粒径、物相结构、和发光性能的影响。将真空干燥过的纳米晶Gd_2O_3:Tb~(3+)置于马弗炉中分别以600, 800, 1000℃进行煅烧,得到的样品经XRD表征后发现:当煅烧温度为800℃时,得到立方相结构的纳米Gd_2O_3:Tb~(3+)。通过研究不同Tb~(3+)离子掺杂浓度下纳米晶Gd_2O_3:Tb~(3+)的荧光强度表明:当Tb~(3+)离子浓度为5.0%时,纳米晶Gd_2O_3:Tb~(3+)的发射强度最强,尤其是在主发射峰545 nm附近Tb~(3+)的~5D_4→~7F_5能级跃迁峰,其峰值强度比掺杂浓度为2.5%时提高了39%; Tb~(3+)掺杂浓度升高至7.5%时,样品发生了浓度猝灭导致光谱强度下降。  相似文献   

13.
Exploring a new tuning way to facilely realize single-band red emission in trivalent rare-earth ions(RE~(3+)) doped upconversion(UC) materials is still desirable.In this work,the intense single-band red emission is achieved by co-doping only Ho~(3+)in the BiOCl:Er~(3+) under 1550 nm excitation.In the BiOCl layered host,co-doping Ho~(3+)can further enhance the red emission and simultaneously suppress the green emission of Er~(3+),and thus obviously improve the red-to-green(R/G) ratio.It is found that Ho~(3+)does not se rve as ene rgy trapping through the ~5 I_6 state as in traditional UC materials but acts as ET bridge(~4 S_(3/2),~2 H_(11/2)(Er~(3+))→~5 F_4,~5 S_2(Ho~(3+))→~4 F_(9/2)(Er3+)).The tuning mechanism of Ho3+is discussed in detail and further confirms through a comparative experiment.Our research gives an unusual perspective to tune the UC behavior of Er3+through co-doping Ho~(3+),which might be inspiring for achievement of single-band red UC emission.  相似文献   

14.
采用溶胶-凝胶法制备合成了(Y_(0.98-x)Yb_xEr_(0.02))_2Ti_2O_7(x=0, 0.02, 0.04,…,0.10)荧光粉,分别采用XRD和荧光光谱仪对样品的结构和上转换发光性能进行了表征.研究了Yb~(3+)掺杂浓度对样品上转换发光性能的影响,并对样品的发光机理进行了研究.结果表明,所得样品为面心立方结构的烧绿石相.在980 nm激发下,样品展现出很强的上转换荧光发射并且发光颜色可以通过Yb~(3+)掺杂浓度来调节.样品上转换绿光和红光发射均为双光子过程并且交叉弛豫过程在上转换红光发射过程中占据主导作用.  相似文献   

15.
研究采用高温固相法合成Eu~(3+),WO_4~(2-)共掺杂Na_2CaSiO_4系列红色荧光粉。通过X射线粉末衍射和荧光分析,研究荧光粉的结构和发光性能。考察了Eu~(3+),WO_4~(2-)掺杂量对荧光粉发光性能的影响。结果表明,掺杂了Eu~(3+),WO_4~(2-)后Na_2CaSiO_4仍为纯相,属立方晶系结构,但掺杂后晶胞参数发生变化,说明Eu~(3+),WO_4~(2-)已经进入晶格中。荧光粉发光强度随Eu~(3+),WO_4~(2-)掺杂含量的增加而增大。Eu~(3+)在晶体中的含量为20%时(以Na_2CaSiO_4物质的量为基准),荧光粉Na_2CaSiO_4∶Eu~(3+)的发光强度达到最大值。当WO_4~(2-)在晶体中的含量为0.07%时,此时,发射光的强度是掺杂前的2.74倍,色坐标为(0.66,0.34),更接近标准色坐标(0.67,0.33)。  相似文献   

16.
采用湿化学法合成单基质的白光发射的Gd_3PO_7∶Dy~(3+)荧光粉,使用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、荧光光谱等对样品的物相结构、形貌与光学性能等进行表征。XRD检测结果表明所制备的样品为含有微量杂质相的Dy~(3+)掺杂单斜结构的Gd_3PO_7晶体。荧光光谱检测结果表明在276 nm属于Gd~(3+)的特征激发带激发下,发射出Dy~(3+)的特征黄色光发射带(~4F_(9/2)→~6H_(13/2))与蓝色光发射带(~4F_(9/2)→~6H_(15/2)),证实在Gd_3PO_7∶Dy~(3+)样品中出现了由Gd~(3+)到Dy~(3+)的能量传递现象。样品的发光强度随pH值和Dy~(3+)掺杂量的变化而变化,在pH值为6.00、Dy~(3+)掺杂量为0.5%的条件下制备的样品呈现相对更强的发光强度。Dy~(3+)掺杂量直接影响着Gd_3PO_7∶Dy~(3+)样品的发光颜色,当Dy~(3+)掺杂量为3%时所制备的Gd_3PO_7∶Dy~(3+)样品可发射出色坐标为(0.335,0.345)的白色光,这表明Gd_3PO_7∶Dy~(3+)是一种潜在的单基质白光发射荧光材料。  相似文献   

17.
《中国钨业》2017,(3):65-70
采用高温固相法合成了NaGd(WMo)O_(8-x/2)F_x:Eu~(3+)(x=0、0.1、0.2、0.3、0.4、0.5)系列红色荧光粉。分别采用X射线衍射、荧光光谱测试手段对所得粉末的晶型及其发光性能进行了表征分析。结果表明,该系列红色荧光粉均为白钨矿四方晶系结构,空间点群结构为I41/a(88),可被近紫外光395 nm有效激发,其最强发射峰位于616 nm处,属于Eu~(3+)的~5D_0→~7F_2电偶极跃迁。F-离子掺杂量为0.2 mol时发光强度最强,与未掺杂F-相比其发光强度提高了41%,其色坐标为(0.653,0.336)。由此可见,NaGd(WMo)O_(7.9)F_(0.2):Eu~(3+)是一种具有潜在应用价值的白光LED红色荧光粉。  相似文献   

18.
A series of Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) and Na_3Bi_(1–x)(PO_4)_2:xEu~(3+) phosphors were successfully synthesized by solid-state method.The structure and luminescence properties were carefully investigated.The excitation spectra presented an obvious excitation band,and the peak was located at 396 nm,which matched well with the popular emissions from near-UV light-emitting diode chips.With the phase of Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) changing to that of Na_3Bi_(1–x)(PO_4)_2:xEu~(3+),the intensity of magnetic dipole transition(~5D_0→F_1) at 598 nm became stronger than that of electric dipole transition(~5D_0→~7F_2) at 621 nm.Under 396 nm excitation,the chromaticity coordinates and the decay curves of the entitled phosphors were also investigated.Based on all experiments without concentration quenching,we could control the luminescence intensity of the material by adjusting the doping amount of the active ions.All results indicated that Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) and Na_3Bi_(1–x)(PO_4)_2:xEu~(3+) phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes.  相似文献   

19.
研究了以尿素为沉淀剂,通过改变加热方式、溶液pH、Eu~(3+)掺杂量及煅烧温度等条件,采用微波辅助液相法制备Y_2O_3:Eu~(3+)红色荧光粉,并对所得荧光粉进行检测分析。结果表明:试验所制备的荧光粉为规整的球形,涂敷性好,可以被近紫外激发光有效激发,发射主峰位于614nm处,归属于Eu~(3+)的~5 D_0→~7 F_2跃迁;该红色荧光粉可应用在白光LED。  相似文献   

20.
《稀土》2017,(1)
采用微波法成功合成了具有特殊荧光性质的Eu~(3+)掺杂LaF_3和CaF_2荧光粉。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光光谱(PL)等分析手段对样品的结构、形貌以及发光性能进行了表征。深入探讨了酒石酸钠、Eu~(3+)掺杂量对合成荧光粉发光性能的影响。实验结果表明,酒石酸钠添加量和Eu~(3+)的掺杂量对其荧光性能具有较大影响;摩尔比的变化使Eu~(3+)从磁偶极跃迁占主导转化为电偶极跃迁占主导,进而使主峰位置从之前的588 nm处变成613 nm处。但没有引起其他峰位置的变化,说明Eu~(3+)进入了LaF_3和CaF_2的晶格之中,而没有其他的变化。  相似文献   

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