白光LED用KNaCa2（PO4）2∶Dy3+材料的制备与发光特性研究

采用高温固相法制备了KNaCa2(PO4)2∶Dy3+发光材料并对其发光特性进行了研究。光谱显示,KNaCa2(PO4)2∶Dy3+激发谱为300～500nm范围内的一系列锐谱,可被InGaN管芯和蓝光有效激发。尤其在385nm紫外光激发下,样品呈现较强白光发射,主发射峰位于485和577nm,对应Dy3+的4F9/2-6 H15/2、4F9/2-6 H13/2跃迁,形成"黄+蓝"单一基质白光。研究了Dy3+掺杂浓度对KNaCa2(PO4)2∶Dy3+发光性能的影响,随Dy3+浓度增加,发光强度先增大后减小,最佳掺杂浓度为0.04mol,Y/B值在较小范围内先增大后减小。根据Dexter理论分析其浓度猝灭机理为电偶极-电偶极相互作用。测量并标定了Dy3+不同浓度下样品的色坐标均呈现白光发射。研究表明,KNaCa2(PO4)2∶Dy3+材料是一种适合紫外-近紫外-蓝光激发的单一基质白光荧光粉。     

Luminescent properties of KNaCa2（PO4）2：Dy3＋ phosphor for white LED

采用高温固相法制备了KNaCa2（PO4）2：Dy3＋发光材料并对其发光特性进行了研究。光谱显示,KNaCa2（PO4）2：Dy3＋激发谱为300～500nm范围内的一系列锐谱,可被InGaN管芯和蓝光有效激发。尤其在385nm紫外光激发下,样品呈现较强白光发射,主发射峰位于485和577nm,对应Dy3＋的。F9/2-6H15／2、4F9/2-6H13/2跃迁,形成“黄＋蓝”单一基质白光。研究了Dy3＋掺杂浓度对KNaCa2（PO4）2：Dy3＋发光性能的影响,随Dy3＋浓度增加,发光强度先增大后减小,最佳掺杂浓度为0．04mol,Y／B值在较小范围内先增大后减小。根据Dexter理论分析其浓度猝灭机理为电偶极一电偶极相互作用。测量并标定了Dy抖不同浓度下样品的色坐标均呈现白光发射。研究表明,KNaCa2（PO4）2：Dy3＋材料是一种适合紫外-近紫外-蓝光激发的单一基质白光荧光粉。     

红色荧光粉BaZn2(PO4)2:Eu3+的制备及其光谱特性

采用高温固相法制备了BaZn2(PO4)2:Eu3+红色荧光材料.测量了BaZn2(PO4)2:Eu3+材料的激发与发射光谱,激发峰位于360-400nm之间,发射光谱主峰位于595nm处.研究了BaZn2(PO4)2:Eu3+材料在595nm的主发射峰强度随Eu3+浓度的变化,发射峰强度先随Eu3+浓度的增加而增大;...     

Eu2+在Sr2SiO4·SrCl2材料中的发光特性

采用高温固相法制备了Sr2SiO4.SrCl2∶Eu2+荧光粉,并研究了材料的发光特性。X射线衍射结果显示,Sr2SiO4.SrCl2∶Eu2+材料是由SrCl2∶Eu2+和Sr2SiO4∶Eu2+构成的复合化合物。以320nm紫外光作为激发源,测得材料的发射光谱呈宽谱特征,覆盖350～600nm。在0.5%～2%范围增大Eu2+掺杂量时,位于蓝色光区域的发射峰位置没有变化,为403nm,处于长波方向的发射峰呈现出先红移、后蓝移的变化趋势,但两发射峰的强度均明显减小。监测两发射峰,所得结果分别对应SrCl2∶Eu2+和Sr2SiO4∶Eu2+材料的激发光谱,覆盖250～400nm。分析认为,材料的光谱分布及发射强度的变化与晶场环境及处于不同Sr2+格位上Eu2+间的能量传递等有关。     

Ca10K（PO4）7:Eu3+红色荧光粉的制备及其发光性质

高温固相法合成了Ca10-xK(PO4)7:xEu3+(x=0.02,0.04,0.06,0.08,0.10,0.12,0.14和0.16)的红色荧光粉。X射线衍射表明,样品具有标准的Ca10K(PO4)7六角晶体结构,且无第二相存在。在393nm的波长激发下,样品获得由Eu3+的4f-4f跃迁产生红光发射,其中以613nm附近的5 D0→7F2电偶极跃迁发射为最强。通过调节Eu3+的掺杂浓度,获得了色坐标与商业化Y2O2S:Eu3+荧光粉十分接近的接近纯色的红色荧光粉。Ca10K(PO4)7:Eu3+是一种可望应用于紫外激发的白光LED的红色荧光粉。     

KBaPO4:Tb3+材料制备及其发光特性

采用高温固相法合成了KBaPO4:Tb3+绿色发光荧光粉,并研究了材料的发光性质.KBaPO4:Tb3+材料呈多峰发射,发射峰位于437、490、545、586和622 nm,分别对应Tb3+的5D3→7F4和5D4→7FJ=6,5,4,3跃迁发射,主峰为545 nm;监测545 nm发射峰,所得激发光谱由4f 7-5d1的宽带吸收(200～330 nm)和4f-4f电子吸收(330～400 nm)组成,主峰为380 nm.研究了Tb3+掺杂浓度,电荷补偿剂Li+、Na+、K+和Cl-,及敏化剂Ce3+对KBaPO4:Tb3+材料发射强度的影响.结果显示,调节激活剂浓度、添加电荷补偿剂或敏化剂均可在很大程度上提高材料的发射强度.上述结果表明KBaPO4:Tb3+材料是一种很好的近紫外光激发型高效绿色发光荧光粉.     

Ca_2SiO_3Cl_2∶Eu~(3+)材料的发光特性

采用高温固相法合成了Ca2SiO3Cl2∶Eu3+红色发光材料。利用X射线分析了材料的晶体结构,其为四方晶系;在400nm近紫外光激发下,材料呈红色发射,主发射峰位于582、599、623、655和691nm,分别对应Eu3+的5D0→7F0、7F1、7F2、7F3和7F4特征跃迁;监测599nm最强发射峰,激发光谱覆盖200～450nm,主激发峰位于400nm。研究了Eu3+摩尔浓度对Ca2SiO3Cl2∶Eu3+材料发射强度的影响,结果显示,随Eu3+浓度的增大,强度先增大、后减小,Eu3+浓度为1%时,强度最大。引入Li+后,材料的发射强度进一步增大。     

Sr2NaMg2V3O12的合成及发光性研究

采用高温固相法制备了Sr2NaMg2V3O12荧光粉,研究了焙烧温度、保温时间和NH4VO3用量等工艺参数对合成产物发光性能的影响,得出优化的工艺条件为NH4VO3过量1.5%,600℃预烧2h后900℃保温6h。所合成Sr2NaMg2V3O12荧光粉在紫外激发下发淡蓝绿色近白光,荧光光谱分析结果显示其激发峰主要位于波长小于390nm的近紫外和紫外区,发射谱带为400～640nm,发射主峰位于470nm左右,有望成为新型近白光LED荧光粉。     

Ca_8MgY(PO_4)_7:Re~(3+)(Re~(3+)=Eu~(3+),Ce~(3+),Tb~(3+))发光材料的合成及发光性能研究

采用固相法成功合成了具有β-Ca3(PO4)2结构的发光材料Ca8MgY(PO4)7∶Re3+(Re3+=Eu3+,Ce3+,Tb3+)。XRD、FT-IR及TG-DSC的测试结果表明,该发光材料的最佳烧结温度为1 200℃。PL测试结果表明,在252nm紫外光激发下,Ca8MgY(PO4)7∶Eu3+呈现Eu3+的特征发射,其中以位于612nm红光发射为主(5D0-7F2),Eu3+的最佳掺杂浓度为5.0%(摩尔分数)。在295nm紫外光激发下,Ce3+激活的Ca8MgY(PO4)7由峰值位于363nm的带状5d1-4f1发射为主,Ce3+的最佳掺杂浓度为1.0%(摩尔分数)。在228nm紫外光激发下,低掺杂浓度的Ca8MgY(PO4)7∶Tb3+以位于5D3-7FJ的蓝光发射为主,高掺杂浓度的Ca8MgY(PO4)7∶Tb3+以5D4-7FJ绿光发射为主,这是由于Tb3+的交叉弛豫造成的。Tb3+的最佳掺杂浓度为7.0%(摩尔分数)。     

白光LED用新型红色荧光粉Sr5（BO3）3Cl:Eu3+的制备与发光特性

采用高温固相法合成了Sr5(BO3)3Cl:Eu3+新型红色发光材料,并对其结构和发光特性进行了研究。X射线衍射测试表明合成材料为纯相Sr5(BO3)3Cl晶体。材料的主发射峰位于587,596,613nm和626nm,对应Eu3+的5 D0→7F1,7F2辐射跃迁。监测626nm发射峰,激发光谱主峰位于392nm,可被InGaN管芯有效激发。通过时间分辨光谱测得Eu3+离子5 D0能级的荧光寿命约为2.28ms。研究了Eu3+离子掺杂浓度对Sr5(BO3)3Cl:Eu3+发光性能的影响,结果随着Eu3+离子浓度的增大,样品的发光强度先增大后减小,最佳掺杂浓度为16%(摩尔分数)。计算了Eu3+离子浓度猝灭的临界距离为1.46nm。测量了不同Eu3+浓度样品的色坐标,均位于色品图红光区,符合NTSC标准。     

Luminescence properties of nano-sized Sr2MgSiO5: Eu2+, Mn2+ phosphors prepared by the sol-gel method

Nano-sized Sr2MgSiO5:Eu2+, Mn2+ phosphor was synthesized by the sol-gel method. The preparation conditions of the precursor were determined. The effect of Eu2+ and Mn2+ content on the luminescence intensity was studied. X-ray diffraction (XRD), photoluminescence spectra (PL), and photoluminescence excitation spectra (PLE) were used to characterize the samples. The results showed that the excitation bands ranged from 250 to 450 nm, and their peaks positioned around 365 nm. The emission spectrum consists of three bands: blue, green, and red, respectively. The blue and green emission bands originate from the center of the Eu2+, while the red emission band is attributed to the energy transfer from Eu2+ to Mn2+. White light can be obtained by mixing the three emission colors. The experiment results show that the Sr2MgSiO5:Eu2+, Mn2+ is a single host phosphor with superior properties for use in white light emitting diodes (white LED).     

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.     

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.     

Self-assembled peanut-like Ln3+ (Ln = Tb, Sm, Eu) doped NaLa(WO4)2: phase control and its relevance to luminescence modification

Ln3+ (Ln = Tb, Sm, Eu) doped NaLa(WO4)2 peanuts were successfully self-assembled by a facile EDTA assisted hydrothermal treatment. EDTA played critical roles in the phase and morphology control, which regulated the phase transformation from monoclinic La2(WO4)3 flowers to tetrahedral NaLa(WO4)2 peanuts. La2(WO4)3:Tb3+ exhibited two broad excitation bands at 280 and 340 nm, which are related to the normal and perturb sites of WO4(2-). However, the excitation band for NaLa(WO4)2:Tb3+ shifted to near ultraviolet region and showed only one broad excitation band originating from perturb sites. Under ultraviolet excitation, La2(WO4)3:Tb3+ displayed green light and NaLa(WO4)2:Tb3+ showed blue-green light consisting of WO4(2-) self-activated blue emission and the characteristic Tb3+ emission. It can be clearly seen that the blue emission of WO4(2-) was not sufficiently quenched in NaLa(WO4)2 as that in La2(WO4)3, because the distortions of crystalline lattice for NaLa(WO4)2 may alter the energy migration processes. When doping with Sm3+ and Eu3+, NaLa(WO4)2 peanuts exhibited white color emission which may find practical applications in solid state lighting devices.     

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%.     

Optical properties of eu doped M-Ga2S4 (M: Zn, Ca, Sr) phosphors for white light emitting diodes

Eu2+ doped M-thiogallate (MGa2S4, M: Zn, Ca, Sr) phosphors were prepared by solid-state reaction. The dependence of luminescent properties, photoluminescence and cathodoluminescence, on M2+ ions was investigated. ZnGa2S4: Eu2+, CaGa2S4: Eu2+, and SrGa2S4: Eu2+ exhibited a green emission band at 540 nm, 560 nm, and 535 nm, respectively. The red-shift between CaGa2S4: Eu2+ and SrGa2S4: Eu2+ was originated from the radius difference of Ca2+ and Sr2+ ions. However, it did not apply to ZnGa2S4 : Eu2+ despite of smaller radius of Zn2+ ion. The particle size of ZnGa2S4 : Eu2+ was much smaller than those of the other thiogallates, leading to extremely low CL emission.     

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.     

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.     

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。