溶胶-凝胶法制备Sr2SiO4:Tb3+绿色荧光粉及其发光性能

采用溶胶-凝胶法合成了一系列适合紫外-近紫外激发的(1-X)Sr₂SiO₄:XTb3+(X=0,0.01,0.02,0.03,0.04,0.05,0.06)绿色荧光粉,并采用X射线衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱(PL)研究了样品的结构及发光性能.由XRD的检测结果可知,合成样品属于单斜晶系的β-Sr₂SiO₄相.由SEM图可知,所有样品都呈无规则块状结构.当监测波长为546 nm,样品的激发光谱的主峰位于370 nm处,属于Tb3+的4f-4f特征跃迁吸收.当激发波长分别为285 nm和250 nm,所有样品在488 nm,547 nm,586 nm,623 nm处都出现了1个强发射峰,分别对应Tb3+的5D₄→7F₆、5D₄→7F₅、5D₄→7F₄和5D₄→7F₃电子跃迁.最强发射峰位于547 nm处,呈现特征为绿光发射.随Tb3+掺杂量增大,发射强度呈现出先增大后减小的变化趋势,即存在浓度猝灭效应.当Tb3+掺杂量为X=0.03时,样品的发光强度最大.      

Structural,morphological and photoluminescence characterizations of Sm3+ doped Y2O3 nano-sized phosphors synthesized by ultrasound assisted sol-gel method

Nanosized 1 at% Sm³⁺doped Y₂O₃ powders were prepared by an ultrasound assisted sol-gel method.Y₂O₃:Sm³⁺powders crystallize in Y₂ O₃ pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λ_em=600 nm exhibit two absorption bands;the first one is assigned to O^2-→Sm³⁺cha...     

钠离子对KNa4B2P3O13: Sm荧光粉发光性能的增强作用研究

通过高温固相法在硼磷酸盐KNa₄B₂P₃O₁₃基质中掺杂稀土Sm3+离子获得橘红色发光性能,研究了电荷补偿剂Na+对该荧光粉发光性能的影响,开展了粉末X射线衍射、红外光谱、紫外可见漫反射、荧光光谱、荧光寿命及量子效率等测试对材料的物相、形貌和发光性能进行了表征。研究结果表明,该荧光粉的荧光发射源于Sm3+的4G_5/2→6H_5/2（562 nm）、4G_5/2→6H_7/2（598 nm）和4G_5/2→6H_9/2（645 nm）跃迁,Na+的掺杂没有改变Sm3+特征发射峰的形状和位置,增强了其发光强度。Na+浓度为1%时,可使发光积分强度提高48%。此外,掺杂Na+对荧光粉的寿命和色坐标无明显影响,其色坐标均位于橘红色区域。      

微波辅助均相沉淀法制备（Y1-x-y, Lay）2O3:xEu3+红色荧光粉

用微波辅助均相沉淀法制备了一系列（Y_1-x-y, La_y）₂O₃:xEu3+(x=0.01~0.05, y=0.05~0.25) 红色荧光粉.研究Eu3+、La3+的掺杂浓度和煅烧温度对荧光粉性能的影响.通过差热分析仪、红外光谱仪、XRD、SEM和荧光分光光度计,对前驱体热重曲线和FTIR曲线、样品的晶体结构、表面形貌及颗粒大小和荧光性能进行表征.结果表明:前驱体组成为 (Y, La, Eu) OHCO₃·nH₂O;所制备样品为立方晶系;SEM显示荧光粉为均匀分散的球形颗粒,粒度为200 nm左右;较为适宜的焙烧温度为900 ℃;La3+掺杂含量y=10 %, Eu3+掺杂含量x=3 %时,样品荧光粉发光性能最好,最大发射波长为614 nm,对应的是Eu3+的5D₀→7F₂跃迁;样品的色坐标为 (0.654, 0.346).所制备的（Y_1-x-y, La_y）₂O₃:xEu3+荧光粉具备较好的发光强度与色纯度.      

BaAl12O19中Mn2+和Tb3+的发光及Tb3+对Mn2+的能量传递

采用溶胶-凝胶法合成了Mn2+、Tb3+单掺及共掺的BaAl12O19荧光粉,对其发光性质和Tb3+对Mn2+的能量传递机理进行了研究.研究结果表明,Tb3+单掺的BaAl12O19荧光粉,发射峰位于440nm、489nm、543nm、587nm和623nm,属于Tb3+的5D3→7FJ和5D4→7FJ (J=6,5,4,3)跃迁发射;Mn2+单掺的荧光粉,发射峰位于516nm,归属于Mn2+的4T1→6A1跃迁发射.Mn2+,Tb3+共掺后,Mn2+的发射强度明显提高,而Tb3+的发光强度降低,Tb3+对Mn2+有能量传递作用.初步证实Tb3+对Mn2+的能量传递机理为激子能量传递.     

Nd3+对红色荧光粉MgSiO3∶Mn2+,Nd3+发光性能的影响

采用高温固相法制备长余辉发光材料MgSiO3∶Mn2+,Nd3+。借助X射线粉末衍射、激发光谱、发射光谱和余辉衰减曲线对样品进行表征,研究Nd3+对这种红色荧光粉发光性能的影响。结果表明,Nd3+的掺入没有引起样品的晶体结构的变化,但对光谱强度和余辉性能有着显著影响,通过比较单掺Mn2+、单掺Nd3+、双掺Mn2+,Nd3+体系的热释光曲线,揭示了双掺体系中Nd3+的陷阱作用。双掺样品中存在Nd3+向Mn2+能量传递,Nd3+的最佳掺杂量为4%。     

NaYF4∶Yb3+/Nd3+纳米粒子近红外热增强发光及温感研究

采用共沉淀法制备了一系列六方相NaYF₄∶Yb³⁺/Nd³⁺纳米粒子。在980 nm激光激发下,观测到峰值分别位于752 nm、804 nm和862 nm的近红外第一生物窗口发光,分别对应于Nd³⁺的⁴F_7/2→⁴I_9/2、⁴F_5/2→⁴I_9/2以及⁴F_3/2→⁴I_9/2辐射跃迁。特别是,Nd³⁺的上述近红外发光展现出优异的热增强发光性质,其中752 nm发光峰在温度从室温升至443 K时增强倍数达到83.7倍。采用发光强度比系统研究了303 K～443 K温度范围内Nd³⁺的温度传感性能,研究发现采用752 nm和862 nm的发射峰强度比,最大相对灵敏度达到3.07%K^-1     

水热法制备Y2O3:Eu及其发光性能的研究

利用水热法制备立方相Y₂O₃:Eu红色荧光粉.在不同掺杂浓度、不同溶液pH值的系列样品中,均观测到Eu3+离子的特征发射.荧光强度与Eu3+离子掺杂浓度关系研究表明:在不同掺杂浓度中,Eu3+离子掺杂浓度为9 %时其相对发射强度最强.在不同溶液pH值所获得的样品中,以溶液pH等于6制备的样品发光效果最好.此外通过与商用Y₂O₃:Eu红色荧光粉比较,发现其荧光强度相当.因此,与传统高温固相法相比,水热法合成Y₂O₃:Eu红色荧光粉是简单易行方案.      

Yb3+，Er3+掺杂Y2Ti2O7荧光粉的制备与上转换发光机理研究

采用溶胶-凝胶法制备合成了(Y_0.98-xYb_xEr_0.02)₂Ti₂O₇(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Yb3+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980nm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Yb3+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.      

Gd3+掺杂增强BaWO4∶Tm3+/Yb3+上转换发光效率及温度传感特性研究

提高发光效率是上转换材料研究中尚需解决的关键问题。通过在BaWO₄∶Tm³⁺/Yb³⁺荧光粉中掺入Gd³⁺,研究其对上转换发光效率和温度传感特性的影响。结果表明,Gd³⁺的掺杂使激活离子Tm³⁺的上转换发光强度显著增强,其中Tm³⁺的蓝光(～485 nm)辐射增强31倍。利用荧光强度比方法研究了基于Tm³⁺的³F_2,3和³H₄两个热耦合能级在313 K～573 K范围内的光学温度传感特性,BaWO₄∶Tm³⁺/Yb³⁺/Gd³⁺测温灵敏度最大值为0.0119 K^-1。可见,BaWO₄∶Tm³⁺/Yb³⁺/Gd³⁺具有高的上转换发光效...     

作为白光LED用铕掺杂氟化镧红色荧光粉的制备与光谱性能研究

采用水热法制备具有单一相六方晶系的LaF₃:Eu3+纳米荧光粉.通过X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光致发光光谱(PL)和荧光衰减曲线对LaF₃:Eu3+纳米荧光粉进行表征.LaF₃:Eu3+荧光粉的激发光谱主要由250 nm处的宽带(O2-→Eu3+的电荷转移跃迁)和一些尖峰(Eu3+ f-f跃迁)构成,其中位于近紫外区396 nm处有一较强的激发峰.通过发射光谱探测Eu3+在LaF₃晶体中的局部晶场环境.在298 K下激发光谱和发射光谱可知,在六方晶系的LaF₃纳米晶体中的Eu3+晶格位置从D_4h降至到C_2v,这是由于晶格变化所造成的.在396 nm激发下,观测到较优掺杂浓度为10%的LaF₃:Eu3+荧光粉在591 nm(5D₀→7F₁跃迁)处有强烈的红色发射峰.其发光性能表明,LaF₃:Eu3+红色荧光粉在近紫外发光二极管领域具有潜在的应用价值.      

阳离子引入对CsPF6:Mn4+红色荧光粉发光性能的影响

采用共沉淀法在室温条件下合成了CsPF₆:Mn4+荧光粉,研究了Li+、Na+、K+阳离子的引入对CsPF₆:Mn4+荧光粉发光强度的影响。所制备的系列荧光粉样品均为立方结构纯相。在蓝光激发下,呈现最强峰位于634 nm处的一系列窄带红色发射。加入K+和Li+后,发光强度增强,加入Na+后发光强度有所减弱,其中加入K+的CsPF₆:Mn4+荧光粉发光强度最强。CsPF₆:Mn4+, K+荧光粉的发射强度随着温度的上升先增强然后由于非辐射跃迁的增加而降低,在423 K时达到最大值,发射强度相较于未引入阳离子的荧光粉发射强度亦增强。阳离子的引入可以有效提升CsPF₆:Mn4+荧光粉的发光性能。      

Energy transfer in Tb~（3＋）,Yb~（3＋） codoped Lu_2O_3 near-infrared downconversion nanophosphors

Tb3+ and Yb3+ codoped Lu2O3 nanophosphors were synthesized by the reverse-strike co-precipitation method. The obtained Lu2O3:Tb3+,Yb3+ nanophosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra. The XRD results showed that all the prepared nanophosphors could be readily indexed to pure cubic phase of Lu2O3 and indicated good crystallinity. The Tb3+→Yb3+ energy transfer mechanisms in the UV-blue region in Lu2O3 nanophosphors were investigated. The experimental results showed that the strong visible emission around 543 nm from Tb3+ (5D4→7F5) and near-infrared (NIR) emission around 973 nm from Yb3+ (2F5/2→2F7/2) of Lu2O3:Tb3+,Yb3+ nanophosphors were observed under ultraviolet light excitation, respectively. Tb3+ could be effectively excited up to its 4f75d1 state and relaxed down to the 5D4 level, from which the energy was transferred cooperatively to two neighboring Yb3+. The Yb3+ concentration dependent luminescent properties and lifetimes of both the visible and NIR emissions were also studied. The lifetime of the visible emission decreased with the increase of Yb3+ concentration, verifying the efficient energy transfer from the Tb3+ to the Yb3+. Cooperative energy transfer (CET) from Tb3+ to Yb3+ was discussed as a possible mechanism for the near-infrared emission. When doped concentrations were 1 mol.% Tb3+ and 2 mol.% Yb3+, the intensity of NIR emission was the strongest.     

Preparation and Upconversion Luminescence of Y3Al5O12 ： Yb^3＋ , Er^3＋ Trapsparent Ceramics

YAG： 1% （atom fraction） Yb^3＋ , 0.5% （atom fraction） Er3＋ transparent ceramics were fabricated by the solid state reaction method using high-purity Y2O3, Al2O3, Yb2O3, and Er2O3 powders as starting materials. The mixed powder compact was sintered at 1760 ℃ for 6 h in vacuum and annealed at 1500 ℃ for 10 h in an air atmosphere. The ceramics consisted of about 10μm grains and exhibited a pore-free structure. The optical transmittance of the ceramics at 1064 nm was nearly 80%. Upconversion emissions were investigated on the ceramics pumped by a 980 nm continuous wave diode laser, and strong green emission centered at 523 and 559 nm and red emission centered at 669 nm were observed, which originated from the radiative transitions of ^2H11/2→^4I15/2, ^4S3/2→^4I15/2, and ^4F9/2→^4I15/2 of Er^3＋ ions, respectively.     

Green, orange, and red upconversion luminescence in Nd3+/Yb3+: Cs2NaGdCl6 powders under 785 nm laser excitation

Nd3+:Cs2NaGdCl6 and Nd3+, Yb3+:Cs2NaGdCl6 polycrystalline powder samples were prepared by Morss method E. Under 785 nm semiconductor laser pumping, the upconversion luminescence of Nd3+ ions in Cs2NaGdCl6 was investigated at room temperature, and three upconversion emissions near 538 nm (Green), 603 nm (Grange), and 675 nm (Red) were observed and assigned to 4G7/2→4I9/2, (4G7/2→4I11/2; 4G5/2→4I9/2), and (4G7/2→4I13/2; 4G5/2→4I11/2), respectively. The dependences of these upconverted emissions on laser power and Nd3+ ion con-eentration were investigated, to explore the upconversion mechanism. The effect of doping Yb3+ ions on the upconversion luminescence of Nd3+ in Cs2NaGdCl6 was also studied under 785 nm laser excitation. The energy transfer processes were discussed as the possible mecha-nism for the above upconversion emissions.