Synthesis and luminescence properties of Sr2SiO4: Eu3+, Dy3+ phosphors by the sol-gel method

The Sr2SiO4:Eu3+, Dy3+ phosphors for white light emitting diodes (LEDs) were synthesized by the sol-gel method. The microstructure and luminescent properties of the obtained Sr2SiO4:Eu3+, Dy3+ particles were well characterized. The results demonstrate that the Sr2SiO4:Eu3+, Dy3+ particles, which have spherical morphology, emitted an intensive white light emission under excitation at 386 nm. The phosphors show three emission peaks: the blue emission at 486 nm corresponding to the 4F(9/2)-6H(15/2) transition of Dy3+, the yellow emission at 575 nm corresponding to the 4F(9/2)-6H(13/2) transition of Dy3+, and the red emission at 615 nm corresponding to the 5D0-7F2 transition of Eu3+. At the same time, the effect of Eu3+ concentration on the emission intensities of Sr2SiO4:Eu3+, Dy3+ was investigated in detail. The phosphors used for white LEDs were obtained by combining near ultraviolet (NUV) light (386 nm) with Sr2SiO4:0.04Dy3+, 0.01Eu3+ phosphors with the characteristic of Commission Internationale de l'Eclairage (CIE) chromaticity coordinate (x, y) of (0.33, 0.34), and color temperature Tc of 5,603 K. In addition, the effect of the charge compensators (Li+, Na+, and K+ ions) on the photoluminescence (PL) emission intensities were studied.     

白光LED用红色荧光粉MMoO4:Eu3+（M=Ca,Sr,Ba）的制备与表征

采用高温固相法制备了红色荧光粉MMoO4:Eu3+(M=Ca,Sr,Ba),用XRD和荧光分光光度计对其物相及发光性能进行表征和研究。结果表明,在800℃时可得到MMoO4(M=Ca,Sr,Ba)物相结构。分别以395nm的近紫外光和465nm的可见光激发样品,MMoO4:Eu3+(M=Ca,Sr,Ba)荧光粉发红光,对应于Eu3+的4f-4f跃迁,其中以616nm发光最强。荧光粉在395nm和465nm的吸收分别与紫外光和蓝光LED芯片相匹配。     

Luminescence properties of nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors

Ba3MgSi2O8:Eu2+, Mn2+ phosphors were synthesized by the sol-gel method and high temperature solid-state reaction method, respectively. XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), PL (photoluminescence spectra), and PLE (photoluminescence excitation spectra) were measured to characterize the samples. Emission and excitation spectra of our Ba3MgSi2O8:Eu2+, Mn2+ phosphors monitored at 441, 515, and 614 nm are depicted in the paper. The emission intensities of 441 and 515 nm emission bands increase with increasing Eu2+ concentration, while the peak intensity of the 614 nm band increases with increasing Mn2+ concentration. We conclude that the 515 nm emission band is attributed to the 4f(6)5d transition of Eu2+ ions substituted by Ba2+ sites in Ba2SiO4. The 441 nm emission band originates from Eu2+ ions, while the 614 nm emission band originates from Mn2+ ions of Ba3MgSi2O8:Eu2+, Mn2+. Nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors prepared by the sol-gel method show higher color rendering and better color temperature in comparison with the samples prepared by high temperature solid-state reaction method.     

Nanostructured CaWO4, CaWO4:Eu3+ and CaWO4:Tb3+ particles: sonochemical synthesis and luminescent properties

Nanostructured CaWO4, CaWO4:Eu3+, and CaWO4:Tb3+ phosphor particles were synthesized via a facile sonochemical route. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, low voltage cathodoluminescence spectra, and photoluminescence lifetimes were used to characterize the as-obtained samples. The X-ray diffraction results indicate that the samples are well crystallized with the scheelite structure of CaWO4. The transmission electron microscopy and field emission scanning electron microscopy images illustrate that the powders consist of spherical particles with sizes from 120 to 160 nm, which are the aggregates of even smaller nanoparticles ranging from 10 to 20 nm. Under UV light or electron beam excitation, the CaWO4 powder exhibited a blue emission band with a maximum at 430 nm originating from the WO4/2- groups, while the CaWO4:Eu3+ powder showed red emission dominated by 613 nm ascribed to the 5D0 --> 7F2 of Eu3+, and the CaWO4:Tb3+ powders showed emission at 544 nm, ascribed to the 5D4 --> 7F5 transition of Tb3+. The PL excitation and emission spectra suggest that the energy is transferred from WO4/2- to Eu3+ CaWO4:Eu3+ and to Tb3+ in CaWO4:Tb3+. Moreover, the energy transfer from WO4/2- to Tb3+ in CaWO4:Tb3+ is more efficient than that from WO4/2- to EU3+ in CaWO4:Eu3+. This novel and efficient pathway could open new opportunities for further investigating the novel properties of tungstate materials.     

煅烧温度对红色长余辉发光材料Sr_3Al_2O_6:Eu~(2+),Dy~(3+)性能的影响

采用溶胶凝胶法合成了Sr3Al2O6:Eu2+,Dy3+长余辉发光材料,利用X射线衍射仪(XRD)对材料的物相进行了分析,采用荧光分光光度计、照度计测定了样品的发光特性。XRD结果表明:随着煅烧温度的升高,SrCO3杂相的衍射峰越来越弱,Sr3Al2O6相的衍射峰越来越强,1200℃时发光基质为纯的Sr3Al2O6相,1250℃时出现新的SrAl2O4杂相。激发光谱和发射光谱结果表明:长余辉发光材料的激发峰位于473nm,发射峰位于612nm,归属于Eu2+的4f65d1→4f7特征发光。温度升至1250℃时,Eu2+的发射峰为612nm和520nm,后者归属于Eu2+在发光基质SrAl2O4中的发光。综合分析得制备Sr3Al2O6:Eu2+,Dy3+发光材料合适的煅烧温度为1200℃,在此温度下,材料具有较好的初始亮度和余辉时间。     

(Sr_(1-x)Ba_x)_(3-y)SiO_5:y Eu~(2+)橙红色荧光粉的制备与发光性能

采用高温固相法在还原气氛下合成橙红色荧光粉(Sr1-xBa)x3-ySiO5∶y Eu2+,并用X射线衍射仪和荧光分光光度计对合成的样品进行表征。结果表明:合成样品的晶体结构与Sr3SiO5相同,(Sr1-xBa)x3-ySiO5∶y Eu2+的荧光光谱为宽带谱,激发峰发射主峰分别位于365nm和592～609nm。随着Eu2+和Ba2+掺杂浓度的不同,样品的热稳定性和发射峰也发生了相应的变化。最终,并对其机理进行简单讨论。     

Fabrication of nano-sized emitting phosphors for photoluminescence films via hydro-thermal synthesis

Nano-sized red and blue emitting phosphors for a photoluminescence film were fabricated via hydrothermal synthesis through the sol-gel process. The nano-sized phosphors had a spherical shape such as the 60-110 nm Y2O2S:Eu3+ phosphor and the 45-90 nm of Y2SiO5:Ce phosphor. Firing at 1000 degrees C for 2 hours resulted in an increase in their size to 90-190 nm for the Y2O2S:Eu3+ phosphor and 70-160 nm for the Y2SiO5:Ce phosphor. Heat treatment of the gel powders of the emitting phosphors above 730 degrees C was recommended because of their crystallization. The maximum excitation and emission intensities of the red and blue phosphors with Y2O2S:Eu3+ and Y2SiO5:Ce were at the wavelengths of 308 nm and 617 nm, and 254 nm and 464 nm, respectively. The photoluminescence of the films increased as increasing the content of the red and blue phosphor powder mixture in the plastic films. The 100 microm-thick PVB film with the nano-sized phosphors showed the maximum photoluminescence of 537 x 1000 counts/sec.     

网络修饰体对铕-镝共掺铝硼硅酸盐玻璃白光发光影响

采用高温熔融的方法,在空气中制备了一系列添加不同网络修饰体氧化物的Eu2 O3和Dy2 O3共掺杂铝硼硅酸盐玻璃,并测试了其在紫外光激发下的发光性能.从发射谱中可以看到归属于Eu2+、Eu3+和Dy3+离子能级跃迁的蓝、绿、黄、红等多色发射带共存.这些发射带之间的相对强度会随着网络修饰体氧化物的改变而变化,从而导致发光色度的变化.加入适当的网络修饰体氧化物可得到合适的白光发射.此外,在空气中制备过程中发生了Eu3+→Eu3+的还原反应.用Li2O取代ZnO时,该还原反应程度降低,而用CaO取代BaO时该还原反应程度增强,其机制与玻璃组分的光碱度有关.     

纳米Sr2MgSi2O7:Eu2+,Dy3+的长余辉发光行为

使用溶胶-凝胶技术合成纳米尺度的Sr2MgSi2O7Eu2+,Dy3+长余辉发光材料,比较了该方法与固相法获得的长余辉粉体的光致发光行为和长余辉性能.溶胶-凝胶获得的纯相Sr2MgSi2O7Eu2+,Dy3+长余辉粉体是由纳米尺度的微晶形成的团聚颗粒,具有光致发光行为和长余辉发光特性.其发射峰位于465nm.而固相合成的粉体具有两个发射峰,分别位于404nm和459nm.产生这些差别的原因在于Eu2+在基质晶格中的不同配位情况.固相合成的粉体的余辉发光性能高于溶胶-凝胶粉体,其原因在于高温固相合成在基质内部产生了更高浓度的电子陷阱.     

近紫外白光LED用红色荧光粉In2（MoO4）3:Eu3+,Bi3+的合成及发光性能

通过固相反应法在1000℃空气气氛中合成了In2(MoO4)3:Eu3+、Bi 3+红色荧光粉。粉体分别用X射线衍射(XRD)、荧光分度计测试。结果表明制备的荧光粉具有单相立方晶体结构,该荧光粉能够被近紫外光(395nm)有效激发,发射高强度的612nm红光。Eu3+浓度为40%(摩尔分数)时,In2(MoO4)3:Eu3+发光强度较高。In2(MoO4)3:0.4Eu3+、Bi 3+荧光粉,Bi 3+浓度为3%(摩尔分数)时,发光强度最大,高于没有掺Bi 3+的In2(MoO4)3:0.4Eu3+荧光粉。和CaMoO4:Eu3+相比,In2(MoO4)3:0.4Eu3+、0.03Bi 3+有较高的发光强度。因此,In2(MoO4)3:0.4Eu3+、0.03Bi 3+是一种可能应用于近紫外白光LED的新型红色荧光粉。     

白光LED用BaMgAl_(10)O_(17):Eu~(2+)Mn~(2+)蓝绿荧光粉

采用高温固相法制备出一种Eu2+,Mn2+共掺的蓝绿色荧光粉BaMgAl10O17:Eu2+,Mn2+(BAM:Eu2+,Mn2+),对其进行了X射线衍射分析和光谱特性的测试.研究表明,它的发射光谱为双峰结构,峰值分别位于455 nm和525 nm处.455 nm发射峰归结为BAM中部分取代Ba2+离子的Eu2+离子的5d→4f的跃迁辐射;525 nm的发射峰源于部分Eu2+能量传递给Mn2+离子,Mn2+的4T1→6A1的跃迁辐射.采用近紫外LED芯片与该荧光粉以及一种红色荧光粉Ca(La0.5Eu0.5)4Si3O13封装,在20 mA前向电流驱动下,获得了显色指数为88的白光LED.     

Eu2+在KNaCa2（PO4）2中的发光及晶体学格位

采用高温固相法制备了KNaCa2(PO4)2:Eu2+蓝色荧光粉,并研究了材料的发光特性.在400 nm近紫外光激发下,材料呈非对称的单峰发射,主峰位于470 nm.监测470 nm发射峰,对应的激发光谱覆盖200~450 nm,主峰位于400 nm,说明材料能够很好的吸收紫外?近紫外光,发射蓝色光.利用van Uitert公式计算了Eu2+取代KNaCa2(PO4)2中Ca2+时所占晶体学格位,得出461和502 nm发射分别归属于八配位和六配位的Eu2+发射.研究了Eu2+掺杂浓度对KNaCa2(PO4)2:Eu2+材料发射强度的影响,结果显示Eu2+的最佳掺杂浓度为1mol%,利用Dexter理论得出其浓度猝灭机理为电偶极?电偶极相互作用.     

Eu2+、Dy3+、Li+共掺杂CaSi2O2N2荧光粉的发光性能

采用高温固相反应法制备了一系列白光LED用CaSi2O2N2:0.05Eu2+,xDy3+,xLi+(0≤x≤0.03)荧光粉.利用X射线衍射仪对样品的物相结构进行了分析,结果表明:Dy3+和Li+离子的掺入没有改变CaSi2O2N2:Eu2+荧光粉的主晶相.利用荧光光谱仪对样品的发光性能进行了测试,发现所有样品的激发光谱均覆盖了从近紫外到蓝光的较宽范围,400 nm激发下得到的发射光谱为宽波段的单峰,峰值位于545 nm左右,是Eu2+离子5d-4f电子跃迁引起的.Dy3+离子掺杂可以提高CaSi2O2N2:Eu2+荧光粉的发光强度,Dy3+与Li+共掺杂可进一步提高荧光粉的发光强度,当Dy3+和Li+的掺杂量为1mol%时,荧光粉的发光强度达到最大值,是单掺杂Eu2+的荧光粉发光强度的157%.     

荧光粉Sr3-x-yAl2O6∶xCe3+,yEu2+的制备及其发光特性

采用高温固相反应法制备了Sr3-x-yAl2O6:xCe3+,yEu2+(x=0,y=0;x=0.04,y=0;x=0.04,y=0.02;x=0.04,y=0.04;x=0.04,y=0.06;x=0.04,y=0.08;x=0,y=0.04)荧光粉,研究其相组成与荧光特性,结果表明,样品具有单相Sr3Al2O6晶体结构。在360nm波长的紫外光激发下,Ce3+离子辐射出峰值在434nm附近的宽谱蓝光。通过能量传递作用,Eu2+离子辐射峰值为517nm左右的宽谱绿光。Ce3+和Eu2+的荧光组合获得了色坐标为(0.2611,0.3313)的近白光发射。样品的激发光谱分布在250～400nm的波长范围,这种荧光粉有望在紫外或近紫外激发的白光LED中获得应用。     

助熔剂和还原气氛对掺铕硅酸锶荧光粉发光性能的影响

采用传统高温固相反应法制备了掺铕硅酸锶荧光粉。在近紫外光激发下,Sr2SiO4:Eu2+发出明亮的黄绿光。其发射光谱由峰值分别位于490nm和550nm的两个属于Eu2+的5d→4f发射带叠加组成。当Eu2+浓度为0.005mol时,发光最强。研究了不同助熔剂(NH4F、NH4Cl、NaF、Li2CO3、H3BO3)及不同还原气氛(5%H2-95%N2混合气体和C粒)对Eu2+掺杂的Sr2SiO4发光性能的影响。结果表明添加助熔剂后大大降低了烧结温度,并不同程度地提高了2个发射峰的强度。结果还表明5%H2-95%N2混合气体还原效果比C粒好。     

Sr0.95Zn0.05Se:Eu2+ and CdSe/ZnS nanocrystals hybrid phosphors for enhancing color rendering index of white light emitting diode

In this study, the yellow emitting cubic structure of Sr0.95Zn0.05Se:Eu2+ phosphors were prepared by high temperature solid state reaction. The Sr0.95Zn0.05Se:Eu2+ phosphors exhibited strong excitation intensity under 400-460 nm region, and broad band emission appeared at around 545-600 nm due to the d-f transition of Eu2+. To enhance the red emission, HDA/TOP/TOPO capped CdSe/ZnS NCs were synthesized via fast nucleation and slow growth method. The narrow emission peak was located at 615 nm with 69% of high quantum yield. Bright white emission was generated by combining a 460 nm InGaN LED chip with CdSe/ZnS NCs and Sr0.95Zn0.05Se:Eu2+ hybrid phosphors. The fabricated white LEDs showed warm white light with acceptable CIE chromaticity coordinate variation from (0.343, 0.255) at 20 mA to (0.335, 0.250) at 50 mA. The addition of CdSe/ZnS NCs contributed to the extension of white light spectrum by supplement of the red region. The color rendering index was largely enhanced from 41.7 to 79.7 compared to the Sr0.95Zn0.05Se:Eu2+ based phosphors white LED.     

Combustion synthesis of Eu2?+? and Dy3?+? activated Sr3(VO4)2 phosphor for LEDs

Combustion synthesis and photoluminescence (PL) characterization of Sr₃(VO₄)₂:Eu,Dy phosphors are presented in this paper. PL emission of Sr₃(VO₄)₂:Eu phosphor shows green broad emission band centring at 511 nm and a red sharp band at 614 nm by excitation wavelength of 342 nm. The PL emission spectrum of Sr₃(VO₄)₂:Dy phosphor exhibits an intense blue emission peak at 479 nm, yellow broad band centring at 573 nm and red band at 644 nm by the excitation wavelength of 426 nm in near visible blue region. The excitation wavelength of Eu (342 nm) and Dy (426 nm) activated Sr₃(VO₄)₂ phosphor are well matched with the excitation of near UV excited solid state lighting and blue chip excitation of light emitting diodes, respectively. The effect of Eu^2 +and Eu^3 +ions concentration on the emission intensity of Sr₃(VO₄)₂ was also investigated. The Sr₃(VO₄)₂:Eu is a potential green and red emitting phosphor as well as Sr₃(VO₄)₂:Dy is blue and yellow emitting phosphor for solid state lighting i.e. white LEDs. The XRD and SEM characteristics of Sr₃(VO₄)₂ materials was also reported in this paper.     

Eu2+掺杂硅基氮氧化物荧光粉的制备与发光特性

为获得接近太阳光的自然发光效果,制备了Eu2+掺杂的硅基氮化物系列荧光粉,并对其发光特性及原理进行研究.采用碳热还原氮化法制备了Eu2+掺杂Sr Si O3-Sr2Si5N8-Sr Si2O2N2红色荧光粉.利用X射线衍射仪(XRD)、荧光分光光度计、MS-CASTEP对产物物相、发光光谱、电子结构进行了测试分析.结果发现:通过调节煅烧工艺参数,可同时获得2种主要物相或者单一物相的荧光粉;所制备的荧光粉,能够在350~400 nm范围内被UVLED很好地激发,根据主晶相的不同,产物的发射光谱可以在400~700 nm波段内调控.采用第一性原理分析了发射峰位于650 nm附近橙红色主晶相Sr2Si5N8∶Eu2+的电子结构和光物理性能,发现该物相为直接带隙半导体材料,Eu2+的4f轨道对费米面电子峰起主要作用.Eu2+掺杂Sr Si O3-Sr2Si5N8-Sr Si2O2N2是优良的、颜色可调控的红色荧光粉材料.     

Eu3+掺杂的硼酸锶系列荧光体的合成及其发光性能

采用溶胶-凝胶法和高温固相反应法合成了Eu^3 掺杂的SrB4O7、SrB2O4、Sr2B2O5、Sr3B2O6荧光体．荧光光谱测试结果表明在不同基质中Eu^3 的荧光发射是有区别的，Sr2B2O5：Eu^3 、Sr3B2O7：Eu^3 发射峰在610nm左右的红光区，SrB2O4：Eu^3 的发射峰在593nm的橙色区，而SrB4O7：Eu^3 则表现出了Eu^2 离子的特征峰，产生这种区别主要是由Eu^3 所处的配位环境不同造成的．荧光体SrB4O7：Eu^3 、SrB2O4：Eu^3 、Sr2B2O5：Eu^3 、Sr3B2O6：Eu^3 的最佳掺杂浓度为2％左右．     

低温燃烧法合成γ-LiAlO2:Eu3+红色荧光粉及其发光性能

低温燃烧法合成了γ-LiAlO2:Eu3+红色荧光粉,采用XRD、SEM、PL对样品进行了结构、形貌及发光性能表征。结果表明样品为四方晶系结构,在395nm的紫外光激发下,样品发射峰位于578、588、613、651和700nm,对应Eu3+离子的5 D0→7FJ=0,1,2,3,4的能级跃迁,主峰位于613nm处。其发光强度与Eu3+和H3BO3的掺量密切相关。