Y_2O_3:Eu~(3+)红色荧光粉的水热合成及性能研究

利用水热法合成了Y2O3:Eu3+荧光粉,并对所制得的样品进行了XRD、SEM以及荧光光谱等表征。荧光测试结果表明,Eu3+掺杂浓度为5%时制备的Y2O3:Eu3+荧光粉荧光强度最好。其最大发射峰位于612 nm,对应于Eu3+的5D0→7F2电偶极跃迁,最大激发波长为240 nm对应于从O2-的2p轨道到Eu3+的4f轨道的电荷转移跃迁。通过对比,发现采用水热法制备的荧光粉要比固相法发光性能更强。     

溶胶-凝胶法合成YAl3(BO3)4:Eu3+荧光粉及其发光性能

以硝酸盐为原料、柠檬酸为配位剂的有机-无机杂化凝胶法合成掺Eu3 的四硼酸铝钇[YAl3(BO3)4:Eu3 ,YAB:Eu3 ]荧光粉.通过X射线衍射、扫描电镜和Fourier变换红外光谱、发光光谱测试,分析了不同温度下焙烧3 h所得粉体的物相、形貌与发光性质.结果表明:YAB:Eu3 的最低合成温度为1 000 ℃,在反应过程中,首先形成中间相Al4B2O9,YBO3和Y3Al5O12,而最终形成单相的YAB:Eu3 .1 100 ℃合成的晶粒尺寸比较均匀,平均粒径尺寸为108.2 nm.发光光谱的测试表明:在252 nm激发下,溶胶-凝胶法合成的YAB: Eu3 荧光粉最强发射峰位于612 nm处,属于Eu3 的5D0→7F2跃迁.Eu3 在YAB: Eu3 基质中的最佳掺杂摩尔分数为10%.     

磷钒酸盐红色发光粉的制备及性能研究

采用燃烧法合成了一种近紫外激发的Ca3((P,V)O4)2:Eu3+发光材料,用X射线衍射谱、荧光光谱对样品进行了表征。结果表明,荧光粉基质Ca3((P,V)O4)2具有畸变的Ca3(VO4)2的结构,VO34-取代了部分的PO34-,但Ca2+的半径与Eu3+接近,因此Eu3+容易进入晶格,表现出良好的发光性能。荧光光谱分析发现荧光粉可被376 nm紫外光激发,主发射峰值位于620 nm(Eu3+离子的5D0→7F2跃迁)的红光,同时详细研究了Eu3+离子掺杂浓度、引发温度及尿素用量对荧光粉发光性能的影响。     

Eu~(3+)掺杂的红色荧光粉制备及荧光性能研究

利用溶胶凝胶法制备了Eu3+掺杂的Y2O3荧光粉。考察了Y2O3:Eu3+的制备条件,进行了物相表征,研究了Y2O3:Eu3+的荧光性能。结果表明,在612 nm波长监测下,Y1.98O3:Eu3+0.02的激发光谱为300~550 nm,最大激发峰值位于466 nm,归属于Eu3+的7F0→5D2的跃迁。在466 nm波长激发下,Y2O3:Eu3+的发射光谱为550~700 nm,最大发射峰值位于612 nm,归属于Eu3+的5D0→7F2的跃迁主峰。Eu3+的掺杂量为x=0.02,p H=1时Y2O3:Eu3+荧光粉可以得到最强的红光荧光粉。     

助熔剂对固相微波法合成MgAl2O4∶Eu发光性能的影响

采用固相微波法研究了助熔剂对MgAl2O4∶ Eu3+荧光粉发光性能的影响.利用XRD和荧光光谱仪对合成产物的物相和发光光谱进行研究,分别探讨了助熔剂的类型及含量对发光性能影响.结果表明,加入NaF,CaF2,B2O3和GeO2为助熔剂时可得到红色发光材料;MgAl2O4∶Eu3+荧光粉主发射峰位于612 nm处,对应Eu3+的5D0→7 F2电偶极跃迁,次强发射峰位于589 nm处,为Eu3+的5D0→7F0的跃迁,Eu3+离子处于非对称中心格位.相对于氟化物,氧化物助熔剂有助于提高样品的发光强度,其中,以B2O3为助熔剂时荧光粉的发光强度最高,其最佳掺杂量为4.5wt％.     

Ca3(VO4)2:Eu3+的燃烧合成及光致发光

以稀土氧化铕、偏钒酸铵、硝酸钙为原料,以尿素作燃烧剂,采用燃烧法合成了Ca3(VO4)2:Eu3+.利用XRD,SEM,荧光分光光度计对其结构、形貌和发光性能进行了表征,并探讨其实际应用的可能性.结果表明,燃烧法合成的稀土Eu3+掺杂ca3(VO4)2荧光粉颗粒规则、均一,发射主峰位于614.0 nm,是现有PDP商品(Y,Gd)BO3:Eu3+红色荧光粉的良好替代品.     

白光LED用红色发光粉La_(9.33)(SiO_4)_6O_2:Eu~(3+)的制备和发光特性

采用高温固相法合成具有磷灰石结构的La9.33(Si O4)6O2:Eu3+红色荧光粉。该荧光粉的性质通过X射线粉末衍射、荧光光谱来表征。La9.33(Si O4)6O2:Eu3+的激发光谱主要由以285 nm为中心的宽谱峰以及一系列由Eu3+离子f-f跃迁的锐线峰组成,在近紫外区有一个最强的激发峰在393 nm。在393 nm激发下,可以观察到La9.33(Si O4)6O2:Eu3+在612 nm处产生强烈的红光。发光特性表明,La9.33(Si O4)6O2:Eu3+荧光粉可能成为潜在近紫外芯片用红色荧光粉。     

Gd_3Al_5O_(12)∶Eu~(3 )柠檬酸盐硝酸盐燃烧法合成及其发光性能研究

采用柠檬酸盐硝酸盐燃烧法,在较低的温度(900℃)下成功地合成单一晶相Gd3Al5O12∶Eu3 发光粉体,紫外激发荧光光谱分析表明,粉体615 nm和593 nm荧光发射源于Eu3 的5D0-7F2和5D0-7F1跃迁.该方法中各工艺条件(如pH值、柠檬酸/金属离子比、煅烧温度)对Gd3Al5O12∶Eu3 发光性能均有影响,通过试验得出了获得最佳发光性能荧光粉体的工艺参数.     

红色荧光粉YAl3(BO3)4:Eu3+的制备及发光性能研究

以稀土氧化物、硝酸铝和硼酸为原料,高温固相反应制备了单相红色荧光粉YAl3(BO3)4:Eu3+,用X射线衍射和发射光谱对荧光粉末的结构和发光性能进行了分析.研究了煅烧温度、Eu3+掺杂量对其发光性能的影响.结果表明,反应物在1 250 ℃下煅烧可制得单相YAl3(BO3)4:Eu3+晶体,在YAl3(BO3)4:Eu3+晶体中,Eu3+取代了YAl3(BO3)4晶体中Y3+,占据了非对称中心格位.在394 nm的紫外光激发下,YAl3(BO3)4:Eu3+荧光粉具有很强的发光性能,与(Y,Gd)BO3:Eu3+荧光粉相比,最强发射线波长由596 nm变为618 nm,由橙红色光变为红色光,色纯度有了很大提高.Eu3+的最佳掺杂量为8%(物质的量分数).     

碱金属对ZnMoO4:Eu3+红色荧光粉发光性能的影响

以(NH4)6Mo7O24·4H2O、Zn(CH3COO)2·2H2O、Eu(NO3)3·6HO2、Li NO3、Na NO3、KNO3为原料,采用高温固相法合成了Zn Mo O4:Eu3+和Zn Mo O4:Eu3+, M+(M+=Li+、Na+、K+)红色荧光粉,用X射线衍射、光致发光光谱和荧光衰减曲线,对荧光粉的结构和发光性能进行表征。研究结果表明,掺入Eu3+、Li+、Na+、K+,没有改变Zn Mo O4三斜晶系的晶体结构。在393nm波长下激发,与单掺9%的Eu3+荧光粉相比,共掺6%(Li+、Na+、K+)的荧光粉在616nm处的发光强度,分别是单掺的1.17倍、0.79倍和-0.14倍。R值(5D0→7F2与5D0→7F1发射光的强度之比)分别为:REu3+=7.18,RLi+=8.25,RNa+=8.36,RK+=8.62。荧光粉的荧光寿命分别为:τEu=0.6582ms,τLi+=0.4177ms,τNa+=0.3293ms,τK+=0.3562ms。Li+适合用于增强Zn Mo O4:0.09Eu3+红色荧光粉的发光,Li+用量为8%时,其在616nm处的发光强度是单掺Eu3+的1.63倍。     

Modification of Optical Properties of SrAl_2O_4：Eu~（2＋）,Dy~（3＋） Phosphor by Terbium Doping

以尿素为燃料,采用快速燃烧法在650℃合成了Tb3＋掺杂的SrAl2O4：Eu2＋,Dy3＋新型长余辉光致发光材料。研究了Tb3＋掺杂对Eu2＋,Dy3＋共激活的铝酸盐长余辉发光材料的发光特性的影响。X射线衍射分析结果表明：当Tb3＋的掺杂量x=0.17%时,合成的样品结构为单相SrAl2O4单斜晶系。光致发光测试结果表明：样品的激发光谱为峰值位于345nm附近的连续宽带谱,发射光谱为峰值位于510nm左右的连续宽带谱。余辉衰减曲线结果表明：Tb3＋的适量掺杂可以提高铝酸锶的余辉性能。与SrAl2O4：Eu2＋,Dy3＋相比,掺杂Tb3＋有利于形成结晶度良好的固溶体,样品中的晶体细密紧凑,颗粒粒径约为100nm。     

Chemical Synthesis of a Blue-Emitting NaSr1−X PO4:EuX Phosphor Powder

Pure, crystalline, blue-emitting NaSr_{1− X} PO₄:Eu _X with X =0–0.06 phosphor powder is formed by the thermal decomposition of a metal–nitrate–citrate–polyethylene glycol complex at 1300°C in a reducing atmosphere. The resulting phosphor powder emits blue luminescence with a peak intensity at 428 nm under ultraviolet excitation at 374 nm. Compared with the powder synthesized by a conventional solid-state reaction, the chemically prepared powder exhibits a higher emission intensity and requires a lower Eu content to reach the maximum intensity.     

Eu2+-Doped Glass Ceramics Containing BaF2 Nanocrystals as a Potential Blue Phosphor for UV-LED

The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals were prepared and their luminescence properties were investigated. The excitation spectra of Eu²⁺-doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED) centered at 380 nm. The 450 nm emission of Eu²⁺ in glass ceramics under the 385 nm excitation was much stronger than that in glass. The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals may be used as a potential blue-emitting phosphor for UV-LED.     

LiCa3MgV3O12:Sm3+: A new high-efficiency white-emitting phosphor

A novel single-phased white-light-emitting phosphor Sm³⁺ doped LiCa₃MgV₃O₁₂ (LCMV) was developed. The LCMV host was one self-activated bluish-green emitting phosphor, which possessed an efficient excitation band in the 250–400?nm wavelength range and showed an intense broadband bluish-green emission with internal quantum efficiency (IQE) of 39%. Doping Sm³⁺ ions in to LCMV host induced tunable-color emissions, due to the energy transfer from [VO₄]^3? to Sm³⁺ ions. Importantly, under 340?nm excitation, the LCMV:Sm³⁺ can emitted bright white light by combining the self-activated luminescence of LCMV host and the red emissions of Sm³⁺ ions, and the IQE of the white-emitting composition-optimized LCMV:0.01Sm³⁺ phosphors reached up to 45%. These white-emitting LCMV:Sm³⁺ phosphors have potential applications in white light-emitting diodes and optical display devices.     

The luminescence spectroscopy and thermal stability of red-emitting phosphor Ca9Eu(VO4)7

Eu-based vanadate Ca₉Eu(VO₄)₇ phosphor was synthesized by the solid state reaction method and was characterized by X-ray powder diffraction (XRD). The photoluminescence excitation and emission spectra, fluorescence decay curves and the dependence of luminescence intensity on temperature were investigated. The phosphor can be efficiently excited by near UV light to realize an intense red luminescence (614 nm) corresponding to the electric dipole transition ⁵D₀ → ⁷F₂ of Eu³⁺ ions. The crystallographic site-occupations of the Eu³⁺ ions in Ca₉Eu(VO₄)₇ were investigated by the site-selective excitation and emission spectra, and the fluorescence decay curves in the ⁵D₀ → ⁷F₀ region using a pulsed, tunable, narrowband dye laser. The red luminescence together with the thermal stability was discussed on the base of the Eu³⁺ site-distribution in Ca₉Eu(VO₄)₇ host.     

Synthesis and photoluminescence properties of novel Ca2LaSbO6:Mn4+ double perovskite phosphor for plant growth LEDs

A novel Mn⁴⁺ activated Ca₂LaSbO₆ (CLS) far-red phosphor was synthesized by high temperature solid state reaction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence spectra, ultraviolet-visible spectra, luminescence decay times, emission-temperature relationship and internal quantum efficiency (IQE). It is found that CLS:Mn⁴⁺ phosphor has a strong broad excitation band in the range of 200–550?nm. The samples can be excited by ultraviolet and blue light. There is a wide emission band centered at 685?nm between 600?nm and 760?nm. The optimum doping concentration of Mn⁴⁺ is approximately 0.5?mol%. In addition, all the CIE chromaticity coordinates of CLS:0.005Mn⁴⁺ located at far-red region. The concentration quenching mechanism is the dipole-dipole interaction of Mn⁴⁺ activator. Importantly, the CLS:0.005 Mn⁴⁺ sample has an IQE of up to 52.2%. Finally, a 365?nm ultraviolet light emitting diode (LED) chip combined with 0.5?mol% Mn⁴⁺ far-red phosphor was used to fabricate the LED device. All the results indicated that CLS:Mn⁴⁺ phosphors have potential applications in indoor plant cultivation.     

The doping concentration dependent tunable yellow luminescence of Sr5(PO4)2(SiO4):Eu

Color tunable yellow-emitting phosphors of Sr_5−5xEu_5x(PO₄)₂SiO₄ (x = 0.05-0.15) were prepared by conventional solid-state reaction method. The X-ray powder diffraction patterns, the photoluminescence excitation and emission spectra were measured. The main excitation bands of the phosphors locate at a broad band extending from 300 to 500 nm, which can match the emission of ultraviolet- and blue-emitting diode chips. The tunable luminescence color was realized by the changing Eu²⁺ doping in Sr₅(PO₄)₂SiO₄. The structure and luminescence properties were investigated. Sr_5−5x(PO₄)₂SiO₄:Eu_5x displays two typical luminescence centers, which originate from two different Sr²⁺ (Eu²⁺) sites in the host. The site-occupation, the luminescence intensity and energy transfer between the Eu²⁺ ions occupying two different crystallographic Sr²⁺ sites were discussed on the base of the luminescence spectra and crystal structure. This is helpful to improve this phosphor for a potential application as a white light emitting diode phosphor.     

First-principles calculation on the electronic structure and optical properties of Eu2+ doped γ-AlON phosphor

The crystal structure, electronic structure, and optical properties of Eu-doped γ-AlON at various Eu concentrations were obtained from density functional theory. Based on the calculated results, the luminescence properties and mechanism of Eu-doped γ-AlON are discussed. The calculated results demonstrate that AlON:Eu²⁺ phosphor exhibits a direct band gap, which is advantageous for luminescence. The absorption spectrum of AlON:Eu²⁺ phosphor has a single intense broad absorption band from 275 to 425 nm with a peak at 355 nm, which is consistent with corresponding experimental excitation spectra. The existence of Eu?N bonds enhanced the local covalence of Eu²⁺, hence the optical stability of AlON:Eu²⁺ phosphor.     

Preparation of Sr2SiO4:Eu phosphors by microwave-assisted sintering and their luminescent properties

An Eu³⁺ activated strontium silicate phosphor was synthesized using a microwave-assisted sintering with a flux NH₄Cl. X-ray powder diffraction analysis confirmed the formation of pure Sr₂SiO₄ phase without second phase or phases of starting materials as Sr_1.9SiO₄:Eu³⁺_0.1 powders sintered at various temperatures in microwave furnace for 1 h. Scanning electron microscopy showed smaller particle size and more uniform grain size distributions are obtained by microwave-assisted sintering. In the PL studies, the excitation spectrum of Sr_1.9SiO₄:Eu³⁺_0.1 phosphors exhibited a broad band in the UV region centered at about 270 nm which was consistent with the absorption spectra. Both microwave sintered and conventionally sintered powders emitted a maximum luminescence centered at 617 nm under excitation of 395 nm, with similar luminescent intensity. The results showed that microwave processing has the potential to decrease the sintering time and required energy input for the production of Sr_1.9SiO₄:Eu³⁺_0.1 phosphors without degrading photoluminescence.     

白光LED用红色荧光粉Gd2-xMo3O9:Eux3+制备和研究

用高温固相法成功制备了Gd2-xMo3O9:Eux3+,用XRD荧光光谱仪对其物相以及粉体的激发和发射光谱进行表征和研究;结果表明:在395和464nm两主激发峰均可得到616nm处红光发射峰,属于Eu3+典型的5D0→7F2的跃迁所致。由464nm激发得到的发射峰为单峰,峰宽较窄且发射强度较强。