YBO3:Eu3+纳米晶发光特性

用水热法制备了YBO₃:Eu³⁺纳米材料，通过改变其反应条件对纳米颗粒的大小和形貌进行了控制，对其发射光谱进行分析并与体材料进行了比较.在纳米材料中，很大比例的稀土离子微观环境受到表面的影响.这种影响可能使稀土离子的Judd-Ofelt参数Ω₂增大，从而使Eu³⁺的⁵D₀→⁷F₂的发射加强，红色发光材料的色纯度提高.     

Ag+掺杂的立方相Y2O3:Eu纳米晶体粉末发光强度研究

采用化学自燃烧法制备了不同Ag⁺掺杂浓度的Y₂O₃:Eu纳米晶体粉末样品(［Y³⁺］∶［Eu³⁺］∶［Ag⁺］=99∶1∶X，X=0—3.5×10^-2)，以及通过退火处理得到了相应的体材料.根据X射线衍射谱确定所得纳米和体材料样品均为纯立方相.实验表明在纳米尺寸样品中随着Ag离子浓度的增加，荧光发射强度随之增加，当X=2×10^-2时达到最大值，其发光强度比X=0时提高了近50%.当Ag离子浓度继续增加，样品发光强度保持不变.在相应的体材料样品中则没有观察到此现象.通过对各样品的发射光谱，激发光谱，X射线衍射图谱，透射电镜(TEM)照片和荧光衰减曲线的研究，分析了引起纳米样品荧光强度变化的原因是由于Ag离子与表面悬键氧结合，从而使这一无辐射通道阻断，使发光中心Eu³⁺的量子效率提高；Ag⁺的引入所带来的另一个效应是使激发更为有效.这两方面原因使发光效率得到了提高.     

Eu2+, Cr3+共掺杂的MAl12O19 (M=Ca, Sr, Ba) 的发光性质及能量传递

三基色荧光粉中, 红色荧光粉性能较差, 为获得性能优良的红色荧光粉, 本文采用高温固相法合成了Eu²⁺, Cr³⁺单掺杂及共掺杂的碱土金属多铝酸盐MAl₁₂O₁₉ (M =Ca, Sr, Ba) 发光体. 实验表明, 在以上三种基质中均存在Eu²⁺→Cr³⁺的能量传递, 利用能量传递可以有效将Eu²⁺的蓝光或绿光转换为红光. 三种碱土金属多铝酸盐基质的晶体结构相似,但Eu²⁺, Cr³⁺发光受晶体场影响,导致在不同的基质中Eu²⁺, Cr³⁺间能量传递效率不同.通过光谱分析及能量传递效率计算发现, 相同掺杂浓度下,CaAl₁₂O₁₉中Eu²⁺→Cr³⁺的能量传递效率最高,SrAl₁₂O₁₉次之, BaAl₁₂O₁₉最低.红光转换率在CaAl₁₂O₁₉中最高.     

Er3+及Er3+/Yb3+掺杂ZrO2-Al2O3的制备及发光性质

采用共沉淀法制备了纳米晶ZrO₂-Al₂O₃∶Er³⁺发光粉体.所制备的粉体室温下具有Er3+离子特征荧光发射,主发射在绿光,其中位于547 nm、560 nm的绿光最强,并得出稀土离子与基质之间有能量传递.对不同煅烧温度下的样品研究表明:因不同温度下所制得的样品晶相不同.研究了纳米晶ZrO2-Al2O3∶Er3+及ZrO₂-Al₂O₃∶Er³⁺/Yb³⁺的上转换发光,并分析了上转换的跃迁机制.发现ZrO₂-Al₂O₃∶Er³⁺的绿光为双光子过程,而ZrO₂-Al₂O₃∶Er³⁺、Yb³⁺的上转换光谱中,红光和绿光也为双光子过程,而极弱的蓝光为三光子过程.讨论了Er³⁺的浓度猝灭现象.最适宜掺杂浓度的原子分数为2%（Er³⁺/Zr⁴⁺）.     

La2Zr2O7:Eu3+纳米棒的合成、表征及其荧光性能

采用传统固相法和水热法成功地制备出棒状La₂Zr₂O₇:Eu³⁺荧光粉. 利用X射线粉末衍射仪、透射电镜和荧光光谱仪等分析了产物的结构、形貌和发光特性. 结果表明红色荧光粉La₂Zr₂O₇:Eu³⁺有良好的晶相,属于立方结构,空间点群为Fd3m; 其形貌主要为纳米棒, 平均直径约47 nm, 长度为50～700 nm. 并对纳米棒的生长机理进行了探讨. 在466 nm蓝光激发下,La₂Zr₂O₇:Eu³⁺荧光粉能发射出Eu³⁺的特征红色荧光,发射主峰位于616 nm处,归属于Eu³⁺的⁵DO_→⁷F2_{超灵敏电偶极跃迁.此外,在产物的发射光谱中能够观察到⁵D}1_→⁷FJ _{(J=0, 1, 2)跃迁和⁵D}1_→⁷FJ _{(J=1, 2, 4)跃迁的劈裂峰,这说明Eu³⁺处在低对称性的晶体场格位中.}     

纳米晶ZrO2:Er3+-Yb3+的制备及其室温上转换发射

用化学共沉淀法制备了ZrO₂:Er³⁺-Yb³⁺纳米晶粉体，所制备的纳米晶粉体具有较强的室温上转换发射和红外发射.研究了样品的晶体结构和上转换发光性质随着Yb³⁺掺杂浓度和煅烧温度的变化关系.通过X射线衍射谱分析发现，经800℃煅烧2h后得到的ZrO₂:Er³⁺-Yb³⁺纳米晶是四方相和单斜相的混合结构，经950℃煅烧2h后得到的样品以单斜相为主，随着Y     

N2O+离子A2Σ+电子态高振动能级的转动结构分析

利用一束波长为36055nm的激光，通过(3+1)共振多光子电离方法制备纯净的且处于X²Π_1/2，3/2(000)态的N₂O⁺离子，用另一束激光激发所制备的离子到第一电子激发态A²Σ⁺的不同振动能级，然后解离，通过检测解离碎片NO⁺强度随光解光波长的变化，得到了转动分辨的N₂     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er³⁺/Yb³⁺:Gd₃Sc₂Ga₃O₁₂和Er³⁺:Gd₃Sc₂Ga₃O₁₂晶体在室温下320—1700nm范围的吸收光谱和500—750nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er^{3+相似文献}   

Eu2+,Mn2+在BaZnP2O7中的发光及Eu2+→Mn2+能量传递

采用高温固相法合成了BaZnP₂O₇:Eu²⁺,Mn²⁺荧光粉，并对其发光性质及Eu²⁺对Mn²⁺的能量传递机理进行了研究.Eu²⁺和Mn²⁺在380 nm和670nm的发射峰分别由Eu²⁺的5d—4f跃迁和Mn²⁺的⁴T₁(^{4相似文献}   

光谱探针法确定Eu3+:ThO2的格位对称性及选择激发下样品的光致发光研究

测量和分析了不同温度下Eu³⁺:ThO₂的激发光谱、发射光谱和荧光 衰减曲线.Eu³⁺:ThO₂晶体是用熔融法生长的.通过12K下格位选择激 发下的发射光谱测量,利用晶场理论,确定了Eu³⁺在ThO₂占据Oh和C_3v两种格位.列表给出了两种格位Eu³⁺离子的晶场能 级和室温及12K下的荧光寿命.讨论了温度对能     

980 nm激发下Er3+/Yb3+共掺杂ZrO2-Al2O3粉末的上转换发光特性

通过固相反应法制备了Er³⁺/Yb³⁺共掺杂ZrO₂-Al₂O₃粉末的样品，并对样品在980nm激光激发下的上转换发光特性进行了研究.从发射光谱可以发现，在可见光范围内有3个强的发光带，一个位于654nm附近的红光带和两个分别位于545nm、525nm附近的绿光带，分别对应于Er³⁺离子的以下辐射跃迁：⁴F_9/2→⁴I_15/2、⁴S_3/2→⁴I_15/2、 ²H_11/2→⁴I_15/2.其中又以Er³⁺离子的⁴F_9/2→⁴I_15/2跃迁产生的红色荧光辐射最强.对其上转换发光机制进行了分析，发现这三个发光过程都是双光子过程.对样品粉末进行了XRD检测，发现ZrO₂主要以立方相为主，并且计算得到了这种立方结构的晶格常数.Al₂O₃固溶于ZrO₂中，Al³⁺嵌入ZrO₂后产生氧空位，导致ZrO₂晶体的对称性降低，这种结构变化更有利于提高上转换效率，即上转换发光强度增强. 关键词： 3+/Yb³⁺')" href="#">Er³⁺/Yb³⁺ 上转换 2-Al₂O₃')" href="#">ZrO₂-Al₂O₃ 荧光 稀土     

Luminescence of La3F3[Si3O9]:Ce

The luminescence properties of Ce³⁺ in La₃F₃[Si₃O₉] are reported. Excitation and emission bands corresponding to 4f¹→5d¹ transitions of Ce³⁺ were identified. The center of gravity of the 5d states lies at remarkable high energy (43.2×10³ cm⁻¹) for Ce³⁺ in a silicate compound. This high value is attributed to the combined oxygen/fluoride coordination of the Ce³⁺ ion. Emission from the lowest 4f5d level to the ²F_5/2 and ²F_7/2 levels was found at 32.4×10³ and 30.4×10³ cm⁻¹. These results are compared with literature data on silicates and fluorides. From the values found for Ce³⁺, predictions are made for the positions of the 4f5d bands of Pr³⁺ and Er³⁺ in La₃F₃[Si₃O₉]. For both ions, it is concluded that in this host lattice emission is expected from high lying 4fⁿ energy levels.     

Tm3+/Yb3 :LiYF4单晶的高效近红外量子剪裁及其在光伏电池中的应用

采用改进的坩埚下降法成功地生长了Tm/Yb共掺氟化钇锂单晶. 该单晶体具有每吸收一个蓝色光子并能发射出2个1000 nm近红外光子的下转换发光效应. 测定了样品的激发光谱、发射光谱和荧光衰减曲线. 在465 nm蓝光激发下观察到由Yb³⁺：²F_5/2→²F_7/2能级跃迁所致的960～1050 nm 波段的发射带,此发光带源于Tm³ 对Yb³ 离子的能量下转换过程. 应用Inokuti-Hirayama模型,研究了晶体的能量转换过程,结果表明Tm³ 向Yb³ 的能量传递是一个电偶极子相互作用机制过程. 当Tm³ 与Yb³ 离子的掺杂浓度为0.49mol%与5.99mol%时,单晶的量子剪裁效率达到最大值167.5%.     

Upconversion emission enhancement of TiO2 coated lanthanide-doped Y2O3 nanoparticles

To investigate the upconversion emission,this paper synthesizes Tm3+ and Yb3+ codoped Y2O3 nanoparticles,and then coats them with TiO2 shells for different coating times.The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2,5.4,and 2.2 times for coating times of 30,60 and 90 min at an excitation power density of 3.21×102 W.cm 2,in comparison with the emission intensity of non-coated nanoparticles.Therefore it can be concluded that the intense upconversion emission of Y2O3:Tm3+,Yb3+ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness.     

Er3+掺杂SiO2复合的Al2O3粉末结构及光致发光特性

采用溶胶-凝胶(sol-gel)工艺制备0.1 mol% Er³⁺掺杂Al₂O₃体系和SiO₂-Al₂O₃复合体系粉末. 实验结果表明：5 mol%的SiO₂复合加入Al₂O₃抑制γ→θ和θ→α相转变. 掺0.1 mol%Er³⁺:Al₂O₃体系粉末，900℃烧结，在1.47—1.63μm波段内光致发光(PL)谱为中心波长1.53 μm、半高宽56 nm的单一宽峰，1000—1200℃烧结，劈裂为多峰PL谱. 掺0.1 mol%Er³⁺:SiO₂-Al₂O₃复合体系粉末，在高达1200℃烧结，仍保持中心波长1.53 μm的单一宽峰PL谱，由于—OH更完全的脱除，PL强度较900℃烧结Al₂O₃体系，SiO₂-Al₂O₃复合体系均提高1个数量级. 关键词： 2-Al₂O₃复合体系')" href="#">SiO₂-Al₂O₃复合体系 掺铒 溶胶-凝胶工艺 光致发光     

Synthesis and characterization of Sr3Al2O6：Eu2＋, Dy3＋ phosphors prepared by sol-gel-combustion processing

A type of red luminescent Sr3Al2O6:Eu2+, Dy3+ phosphor powder is synthesised by sol-gel-combustion processing, with metal nitrates used as the source of metal ions and citric acid as a chelating agent of metal ions. By tracing the formation process of the sol-gel, it is found that it is necessary to reduce the amount of NO3- by dropping ethanol into the solution for forming a stable and homogeneous sol-gel. Thermogravimetric and Differential Scanning Calorimeter Analysis, x-ray diffractionmeter, scanning electron microscopy and photoluminescence spectroscopy are used to investigate the luminescent properties of the as-synthesised Sr3Al2O6:Eu2+, Dy3+. The results reveal that the Sr3Al2O6 crystallises completely when the combustion ash is sintered at 1250 C. The excitation and the emission spectra indicate that the excitation broadband lies mainly in a visible range and the phosphors emit a strong light at 618 nm under the excitation of 472 nm. The afterglow of (Sr0.94Eu0.03Dy0.03)3Al2O6 phosphors sintered at 1250 ℃ lasts for over 1000 s when the excited source is cut off.     

Doping effects of Nb5+ on red long afterglow phosphor CaTiO3:Pr3+

A series of Nb5+ codoped red long afterglow phosphors CaTi1 xNbxO3:Pr03.+002 (0 ≤ x ≤ 0.05) is prepared by a solid state reaction method. Their photoluminescence, phosphorescence and thermoluminescence are investigated. The results indicate that codoping Nb5+ can improve the photoluminescence and phosphorescence property of CaTiO3:Pr3+ significantly. When 3-mol% Nb5+ is codoped, the emission intensity of CaTiO3:Pr3+ is enhanced twice, while the afterglow time is extended from 10 min to about 40 min. Thermoluminescence results reveal that the trapping level of CaTiO3:Pr3+ is reduced from 0.82 eV to 0.62 eV by codoping Nb5+. The effect of Nb5+ doping on enhancing the photoluminescence intensity and afterglow time of CaTiO3:Pr3+ is discussed.     

Synthesis and luminescence properties of Eu, Ce and Tb-activated Sr3La2(BO3)4 under UV excitation

The spectroscopic properties in UV-excitable range for the phosphors of Sr₃La₂(BO₃)₄:RE³⁺ (RE³⁺=Eu³⁺, Ce³⁺, Tb³⁺) were investigated. The phosphors were synthesized by conventional solid-state reactions. The photoluminescence (PL) spectra and commission international de I'Eclairage (CIE) coordinates of Sr₃La₂(BO₃)₄:RE³⁺ were investigated. The f-d transitions of Eu³⁺, Ce³⁺ and Tb³⁺ in the host lattices are assumed and corroborated. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Sr₃La₂(BO₃)₄:Eu³⁺ is 611 nm, and Sr₃La₂(BO₃)₄:Ce³⁺ shows dominating emission peak at 425 nm, while Sr₃La₂(BO₃)₄:Tb³⁺ displays green emission at 487, 542, 582 and 620 nm. These phosphors were prepared by simple solid-state reaction at 1000 °C. There are lower reactive temperature and more convenient than commercial phosphors. The Sr₃La₂(BO₃)₄:Tb³⁺ applied to cold cathode fluorescent lamp was found to emit green light and have a major peak wavelength at around 542 nm. These phosphors may provide a new kind of luminescent materials under ultraviolet excitation.