Er3+掺杂位置对Er3+:BaTiO3薄膜上转换发光的影响

采用溶胶-凝胶法在LaNiO3/Si衬底上制备Er3+掺杂BaTiO3薄膜.通过XRD、AFM和PL图谱分别研究薄膜的晶体结构、形貌以及上转换发光性能.结果表明,薄膜的微观结构和发光性能与Er3+掺杂晶格的位置有关.A位掺杂薄膜较B位掺杂薄膜具有较小的晶格常数和较好的结晶.PL光谱表明:A位掺杂的薄膜和B位掺杂的薄膜都于528 nm和548nm处获得较强的绿色上转换发光以及在673 nm处获得较弱的红光,分别对应Er3+离子的2H11/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2能级跃迁.相对于B位掺杂的薄膜,A位掺杂样品有较强的绿光发射积分强度以及较弱的红光发射相对强度.这种差异可以通过薄膜的结晶状况和交叉弛豫机制来进行解释.     

Yb3+/Er3+/Tm3+共掺氧氟碲酸盐玻璃三基色上转换发光研究

制备了一种新的Yb3 /Er3 /Tm3 共掺氧氟碲酸盐玻璃.研究了ZnF2调整Yb3 /Er3 /Tm3 共掺氧氟碲酸盐玻璃的Raman光谱、吸收光谱和上转换荧光光谱.结果发现,该体系玻璃具有较低的声子能量,在980 nm LD激发下,可以同时观察到明显的蓝色(476nm)、绿色(530和545 nm)和红色(656nm)上转换发光.上转换蓝光(476 nm)是由于Tm3 离子1G4→3H6跃迁,上转换的绿光(530和545 nm)是由于Er3 离子2H11/2→4I15/2和4S3/2→4I15/2跃迁,上转换红光(656nm)是由于Er3 离子4F9/2→4I15/2跃迁.根据吸收光谱以及Yb3 、Er3 和Tm3 离子的能级,分析了Yb3 /Er3 /Tm3 共掺氧氟碲酸盐玻璃的上转换发光机理,发现上转换蓝光是一个三光子吸收过程,而上转换绿光和红光均为双光子吸收过程.研究结果表明,Yb3 /Er3 /Tm3 共掺氧氟碲酸盐玻璃是一种三维立体显示用激光玻璃的潜在基质材料.     

Lu_2O_3:Yb~(3+),Tm~(3+)纳米晶的制备和上转换发光性能(英文)

采用碳酸氢铵(NH4HCO3)为沉淀剂,用共沉淀法制备Yb3+和Tm3+共掺杂的Lu2O3:Yb3+,Tm3+纳米晶。研究Tm3+摩尔分数、Yb3+摩尔分数和煅烧温度对Lu2O3:Yb3+,Tm3+纳米晶的结构和上转换发光性能的影响。结果表明:所制备的纳米晶具有纯的Lu2O3相,结晶性较好。当掺杂的Tm3+浓度超过0.2%(摩尔分数)时,出现浓度淬灭效应。Tm3+和Yb3+的最佳掺杂比分别为0.2%和2%(摩尔分数)。在980nm半导体激光器的激发下,样品发射出蓝光(490nm)和红光(653nm),分别对应Tm3+的1G4→3H6和1G4→3F4跃迁。发射强度与激发功率的关系表明,Tm3+的1G4能级布居是三光子能量传递过程。随着煅烧温度的升高,上转换发光强度增强,这主要是因为随着温度的升高纳米晶表面的OH?减少和纳米晶尺寸增大。     

β-NaYF_4:Yb~(3+),Er~(3+)上转换发光材料的可控合成及其发光性能

采用水热法合成多种形貌和尺寸的NaYF4:Yb3+,Er3+上转换发光材料,探讨螯合剂、敏化剂、激活剂、氟化铵用量及水热时间对目标产物发光性能的影响规律,并通过正交实验优化Yb3+、Er3+共掺杂NaYF4上转换发光纳米材料的合成条件。采用XRD、SEM和荧光光谱对目标产物进行对比分析。结果表明:目标产物为β-NaYF4,在980 nm红外光的激发下,发出明亮的绿光,最强发射峰在542 nm。可通过改变螯合剂的种类来控制生成不同尺寸(纳米级或微米级)和形貌(管状、球形或六棱柱形)的目标产物。所制备的NaYF4:Yb3+/Er3+上转换发光材料分散性好、荧光强度高,在生物探针及生物成像等领域具有潜在的应用价值。     

Er~(3+)-Tm~(3+)-Yb~(3+)掺杂Bi_4Ti_3O_(12)薄膜的上转换白色荧光和铁电性能

通过化学溶液沉积法制备了Er~(3+)-Tm~(3+)-Yb~(3+)共掺杂的Bi_4Ti_3O_(12)薄膜,并研究了薄膜的上转换荧光和铁电性能.在980 nm红外光的激发下,薄膜的室温发射光谱在可见光区域显示岀4个发射带,分别是峰值为478 nm的蓝光发射带,对应Tm~(3+)的~1G_4→~3H_6能级跃迁;峰值为527和548 nm的绿光发射带,对应Er~(3+)的~2H_(11/2)→~4I_(15/2)和~4S1/2→~4I_(15/2)能级跃迁;峰值为657 nm的红光发射带,由Er~(3+)的~4F_(9/2)→~4I_(15/2)和Tm~(3-)的~1G_4→~3F_4能级跃迁产生的发射带复合而成.荧光的颜色可以通过改变Er~(3-),Tm~(3+),Yb~(3+)离子的掺杂浓度加以调节.在固定Tm~(3+),Yb~(3-)浓度的Bi_(3.59-x)Er_xTm_(0.01)Yb_(0.4)Ti_3O_(12)(BEr,TYT)薄膜中,随着Er~(3+)浓度的增加,红、蓝光和绿、蓝光的强度比均增加,Er~(3+)离子的淬灭浓度为1.75‰(摩尔分数,下同);在固定Er~(3+),Yb~(3+)浓度的Bi_(3.593-y)Er_(0.007)Tm_yYb_(0.4)Ti_1O_(12)(BETm_yYT]薄膜中,随着Tm~(3+)浓度的增加,绿、蓝光和红、蓝光的强度比均降低,Tm~(3+)的淬灭浓度为2.5‰;在固定Er~(3-),Tm~(3+)浓度的Bi_(3.98-x)Er_(0.01)Tm_(0.01)Yb,Ti_3O_(12)(BETYb,T)薄膜中,随着Yb~(3+)浓度的增加,蓝、绿光和红、绿光的强度比均增加,Yb~(3-)对Er~(3-)发射的荧光淬灭浓度小于5%,而对Tm~(3-)发射的荧光淬灭浓度大于18%.Bi_(3.5#15)Er_(0.0045)Tm_(0.01)Yb_(0.4)Ti_3O_(12)薄膜上转换荧光值为(0.31,0.34),最接近标准白光的色度坐标(0.33,0.33).在不同功率的红外激光激发下,薄膜荧光的色度坐标变化幅度很小,说明薄膜具有较好的颜色稳定性.通过分析薄膜荧光的上转换机制,从Er~(3+)向Tm~(3-)有明显的能量传递发生,使光谱中红、绿、蓝光的相对强度和稀土离子的淬灭浓度发生明显变化.薄膜的铁电性能测试表有,当Er~(3+),Tm~(3+),Yb~(3+)掺杂的总浓度约为10%时(Bi_(3.5815)Er_(0.0085)Tm_(0.01)Yb_(0.4)Ti_3O_(12),薄膜的铁电剩余极化强度达到最大值,为27.8μC/cm~2.     

Er3 离子掺杂氧氟碲酸盐玻璃的上转换发光

制备了一种新型的单掺铒氧氟碲酸盐玻璃.研究了该玻璃系统的光谱特性,分析了Er3 离子在玻璃中的上转换机理.在室温下,通过980 nmLD激发,可观察到明亮的绿色上转换荧光.光谱测试结果表明:在近紫外和蓝光波段,存在中心波长为410,452,490 nm的发射峰,分别对应于2H9/2→4I15/2,4F5/2,3/2→4I15/2和4F7/2→4I15/2的跃迁.通过比较980 nm可调谐激光器间接激发和488 nm氙灯直接激发获得各发光能级的荧光寿命,Er3 离子在氧氟碲酸盐玻璃中的红、绿光上转换发光过程主要源于能量转移过程.     

Er3 掺杂钡镓锗玻璃上转换荧光淬灭机理研究

制备了30BaO-30Ga2O3-40GeO2-xEr2O3系统玻璃,测量了Er3 在钡镓锗玻璃中的吸收光谱.分别采用488 nm,800 nm和980 nm激发不同浓度Er3 掺杂的玻璃样品,测量了Er3 的4S3/2→4I15/2荧光光谱;并利用488 nm脉冲氙灯激发,测量了Er3 的4S3/2→4I15/2荧光衰减,讨论了Er3 掺杂浓度对4S3/2能级发光强度和荧光寿命的影响.结果表明:随着Er3 浓度的增加,4S3/2→4I15/2荧光强度先增大后减小,在Er3 浓度为1%时出现峰值;而4S3/2能级的荧光寿命呈递减趋势,荧光衰减曲线的非指数成分增加.能量分析表明:Er3 的4S3/2能级和4I15/2能级之间交叉驰豫过程是上转换荧光淬灭的主要通道,而交叉驰豫过程主要源于Er3 电偶极-电偶极间的相互作用.     

Er~(3+)和Yb~(3+)共掺杂ZnS纳米晶的合成及荧光性能（英文）

以巯基乙酸为稳定剂,采用水热法合成了Zn S:Er/Yb纳米晶。利用XRD、TEM、XPS和荧光光谱对合成的纳米晶进行物相、形貌、化学价态及荧光性能进行表征。结果表明:合成的纳米晶晶粒度约5 nm,为闪锌矿结构;由荧光光谱分析可知,激发波长为270nm时,发射光谱中主要出现了470,530和580 nm 3个发射峰,且当合成温度为120℃时,发光峰强度最大。980 nm激发纳米晶时,得到了Er离子在540和650 nm处,~4F_(3/2)→~4I_(15/2)和~4F_(9/2)→~4I_(15/2)的跃迁发射峰。     

Dy3+掺杂γ-AlON基荧光粉的合成及其发光性能

以AlN、Al2O3、Dy2O3为原料,采用高温固相反应法在1900℃、5MPa氮气气氛条件下合成AlON:Dy3+荧光粉,研究了Dy3+掺杂离子浓度对荧光粉的物相组成和发光性能的影响。结果表明:当Dy3+掺杂浓度较低时(x=0.005～0.100)合成纯的AlON相,随着Dy3+掺杂浓度的增大(x=0.125～0.250),出现微量的DyAlO3相。该荧光粉在354nm处有最强激发,其在354nm激发下呈现3个发射峰,分别位于蓝光483nm(19F9/2→6H15/2)、黄光578nm(19F9/2→6H13/2)和红光670nm(19F9/2→6H11/2),其中在578nm处黄光为最强发射。随着掺杂离子Dy3+浓度的增大,其激发峰和发射峰的强度均表现出先增大后减小的变化规律,其中当x=0.050时,发射强度最高。     

微波辐射辅助柠檬酸络合法制备的Ho~(3+)/Tm~(3+)/Yb~(3+)共掺杂CaWO_4的白光性能(英文)

采用微波辐射辅助柠檬酸络合法制备Ho3+/Tm3+/Yb3+共掺杂CaWO4纳米晶升频转换荧光粉。将柠檬酸络合物前驱体在300~700°C热处理3 h。Ho3+/Tm3+/Yb3+共掺杂CaWO4C在400°C时开始结晶,在600°C时结晶完成。经600°C热处理的Ho3+/Tm3+/Yb3+共掺杂CaWO4主要呈球形,且形态均匀。在980 nm的激光激发下,Ho3+/Tm3+/Yb3+共掺杂CaWO4纳米晶出现肉眼可见的明亮的白色升频转换发射,这种现象来自Tm3+的475 nm蓝光发射以及Ho3+的543 nm绿光和651 nm红光发射。通过调整Tm3+和Ho3+的浓度可以控制Ho3+/Tm3+/Yb3+共掺杂CaWO4的CIE色度图从冷到暖白色之间变化。讨论了Tm3+和Ho3+浓度对升频转换光性能的影响以及与激光泵功率相关的影响机制。     

溶胶-凝胶合成Er3 和Ho3 离子掺杂的Gd2(MoO4)3上转换发光纳米晶

采用柠檬酸与乙二醇溶胶-凝胶法合成了Er3 和Ho3 离子分别掺杂的铝酸钆Gd2(MoO4)3纳米晶.用XRD证实了产物的结构,用扫描电镜与透射电镜研究了产物微观形貌与尺寸.在980nm激光泵浦下,Ho3 掺杂Gd2(MoO4)3纳米晶发出很强的位于660nm的红光,而Er3 掺杂Gd2(MoO4)3纳米晶发出很强的位于540nm左右的红光.共掺Yb3 分别对Ho3 与Er3 起着显著的敏化作用.从发光强度与激光功率变化图中可知,Ho3 与Er3 的发光均属于双子光发光过程.     

Enhancement of upconversion luminescence of Y2O3:Er nanocrystals by codoping Li-Zn

The upconversion (UC) luminescence in sol-gel synthesized Li⁺, Zn²⁺, or Li⁺-Zn²⁺ codoped Y₂O₃:Er³⁺ nanocrystals were investigated under the excitation of a 970 nm diode laser. Compared to undoped Y₂O₃:Er³⁺ samples, proper doping of Li⁺-Zn²⁺ leads to an drastic increase of the UC luminescence centered at 560 nm by a factor of 28. The UC luminescence enhancement is a result of the increased lifetime of the intermediate state ⁴I_11/2 (Er). The intensity ratio of the green over red emissions (green/red) is also affected by the codoping of Zn²⁺, Li⁺ and Li⁺-Zn²⁺ ions. Our results demonstrated that the Li⁺-Zn²⁺ codoping in Y₂O₃:Er³⁺ phosphors produced remarkable enhancement of the UC luminescence and green/red ratio, making this nanocrystal a promising candidate for photonic and biological applications.     

Effect of Yb3+ concentration on the structures and upconversion luminescence properties of Y2O3:Er3+ ultrafine phosphors

Y2O3:Er3+ ultrafine phosphors with a varying Yb3+ ion concentration were prepared by a urea homogeneous precipitation method.The results of XRD show that all the samples are of a pure cubic structure and the average crystallite sizes can be calculated as 45,34,and 28 nm for Y2O3:Er3+ ultrafine phosphors with Yb3+ ion concentrations of 0,10%,and 20%,respectively.The lattice constant and cell volume of the ultrafine phosphors decrease with enhancing Yb3+ ion concentration.The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation.The strong green and red upconversion emission were observed,and attributed to the 2H11/2→4I15/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+,respectively.The intensity of red emission increases with increasing Yb3+ ion concentration.The effect of Yb3+ ion concentration on the structures and upconversion luminescence mechanism were discussed.     

Enhanced red emission in LiAl5O8:Fe phosphor by B doping

Fe³⁺, B³⁺ co-doping LiAl₅O₈ phosphor has been successfully synthesized by a solid-state reaction method assisted with wet chemical mixing route. Photoluminescence emission peak is observed at around 672 nm excited at both 290 nm ultraviolet and 565 nm green light. With introduction of a small amount of boric acid, the red emission intensity can be enhanced by 2.62 times under 290 nm excitation and 2.31 times under 565 nm excitation, respectively. It is believed that the substitution of B³⁺ ions for Al³⁺ sites decreases the symmetry of the luminescence center, intensifying the red emission.     

Upconversion dynamics in Er doped nanocrystalline YAlO3

We report the luminescence and upconversion spectra of nanocrystalline YAlO₃ doped with trivalent erbium at concentrations of 5.0, 1.0 and 0.1 mol.%. The powder samples were prepared using a solution combustion reaction method, and the resulting YAlO₃ nanocrystals show, under wide-angle X-ray diffraction, a size in the range 20–40 nm. Efficient green and red emissions are observed at room temperature under continuous-wave pumping at 980 nm. A weak emission can also be detected in the blue at 410 nm. The upconversion dynamics were studied measuring the decay times and the pump-power dependence of the transitions to the ⁴I_15/2 ground state starting from the ²H_11/2, ⁴S_3/2 and ⁴F_9/2 excited states. Excited-state absorption (ESA) is found to be responsible for the higher energy (²H_11/2, ⁴S_3/2→⁴I_15/2) green transitions. On the other hand, for the ⁴F_9/2→⁴I_15/2 red transition a competing energy-transfer upconversion (ETU) mechanism is found, which accounts for the more than 100-fold increase in intensity of the red emission on passing from the lowest (0.1 mol.%) to the highest (5 mol.%) erbium concentration.     

A study on microstructure and luminescent properties of oxyfluoride silicate glass-ceramics with (Ho,Yb):NaYF4 crystallites

Glass-ceramics containing NaYF₄ nanocrystals were prepared by heat-treatment from oxyfluoride silicate-based glass doped with Ho³⁺ and Yb³⁺ ions. The formation of crystalline fluoride phase was confirmed by X-ray diffraction and transmission electron microscopy. Absorption and emission spectra revealed that a fraction of Ho³⁺ and Yb³⁺ ions is incorporated into the NaYF₄ ordered lattice influencing spectroscopic features of glass-ceramics in comparison with those of precursor glass. Green up-conversion emission (545 nm) originating in the ⁵S₂ level in glass-ceramics and up-converted red emission (650 nm) originating in the ⁵F₅ level in as-melted glass were observed under optical pumping into Yb³⁺ absorption band and analyzed. Although both emissions in both materials are achieved by two-photon excitations, the relation between green and red emission intensity in glass-ceramics and glass implies that processes relevant to up-conversion phenomena are different. Based on a careful analysis of relaxation dynamics of Ho³⁺ and Yb³⁺ excited states, the mechanisms involved in conversion of the infrared radiation into the visible emission in these materials are proposed and discussed.     

Red photoluminescence and morphology of Eu doped Ca3La3(BO3)5 phosphors

Europium doped phosphors Ca₃La₃(BO₃)₅ were first synthesized by a sol–gel process technique. The reaction temperature of the sol–gel process was 300 °C lower than that of the solid-state reaction and the reaction time of the sol–gel process was shorter. The photoluminescence properties of Eu³⁺ doped Ca₃La₃(BO₃)₅ indicated that the phosphors exhibited a strong luminescence of ⁵D₀–⁷F₂ transition at 612 nm under the excitation at 237 nm. The emission intensity of the phosphors prepared by the sol–gel process was higher than those prepared by the solid-state reaction. The relationship between optical properties and morphologies were studied. In particular, Li⁺ ion doping effectively enhanced the luminescent properties of the Eu³⁺ doped Ca₃La₃(BO₃)₅ phosphors. The highest brightness was observed in the phosphor Ca₃La_2.82Eu_0.1Li_0.08B₅O_15−δ prepared by the sol–gel process.     

中频反应磁控溅射制备Al2O3:CeCl3薄膜及其光致发光特性

应用中频反应磁控溅射技术制备了Al2O3:CeCl3的非晶薄膜.Ce3+含量和薄膜的化学成分通过X射线散射能谱(EDS)测量.薄膜试样的晶体结构用x射线衍射分析.俄歇电子谱用于对薄膜材料的化学组分进行定性分析.薄膜的光致发光峰是在370 nm到405 nm范围内,它们来自于Ce3+离子的5d1激发态向基态4f1的两个劈裂能级的跃迁.发光强度强烈地依赖于薄膜中的掺杂浓度和沉积时的基片温度.薄膜发光来自于氯化铈分子中的发光中心,而不是其他的掺杂Ce3+离子.随铈含量增加,光致发光峰向低能方向移动,可能与薄膜中存在氯元素有关.     

Ce3+掺杂对GdAl3(BO3)4:Dy3+和GdAl3(BO3)4:Tb3+荧光粉发光性能的影响

用湿化学方法合成了Ce3 /Dy3 及Ce3 /Tb3 共掺GdAl3(BO3)4发光材料.利用X射线衍射仪对其进行了物相分析,结果表明:合成物为纯的六方相GdAl3(BO3)4微晶.利用荧光分光光谱仪进行光谱分析,测定了合成样品的激发和发射光谱.发现在紫外激发下,GdAl3(BO3)4:Dy荧光粉发射出很强的偏黄的白光,其发射峰分别位于480,575和665 nm,对应于Dy3 的4F9/2→6H15/2,13/2,11/2跃迁.掺Ce3 对Dy3 起到敏化作用,GdAl3(BO3)4:Dy,Ce发出很亮的暖白光,且强度是GdAl3(BO3)4:Dy的3倍左右.同时,在Ce3 /Tb3 共掺的样品中,由于Ce3 与Tb3 间的能量传递,Tb3 的541 nm特征峰显著增强.