Ca3Y2(Si3O9)2:Tb3+绿色荧光粉的光谱特性

采用高温固相法制备了Ca₃Y₂(Si₃O₉)₂: Tb³⁺绿色荧光粉,研究了材料的光学性能。X 射线衍射(XRD)结果显示,掺杂少量的Tb³⁺,并未影响Ca₃Y₂(Si₃O₉)₂材料 的晶相结构。Ca₃Y₂(Si₃O₉)₂:Tb³⁺ 荧光粉的激发光谱由较强的4f^75d1宽带吸收(200～300 nm )和较弱的4f-4f电子跃迁吸收 (300～500 nm)构成,主激发峰位于236nm。取波长分别为236、376和482nm的光 作为激发源时,发现样品的主发射峰均位于544 nm,对应Tb³⁺的⁵D 4→⁷F₅跃迁发射。以236nm 紫外光作为激发源,监测544nm主发射峰,随Tb³⁺浓度 的增大,Ca₃Y₂(Si ₃O₉)₂:Tb³⁺的荧光寿命逐渐减小,但在实验范围内并未出现浓度猝灭现象。     

红色荧光粉YF3:Eu3+,Gd3+的制备及发光性能

采用水热法合成了YF₃:xEu³⁺和YF₃:0.14Eu³⁺,0.08Gd³⁺系列荧光粉。通过X射线衍 射(XRD)、 扫描电子显微镜(SEM)、光电子能谱(EDS)、光致发光(PL)和长余辉光谱分别对样品的物相、 结构、形貌、 表面元素、PL和荧光寿命进行了表征。XRD检测表明,合成的样品属正交晶系。ED数据验 证了合成样品的表面元素组分。PL光谱测试表明,YF₃:xE u³⁺的激发光谱由200～300nm的宽带和Eu³⁺ 的系列窄带激发峰组成,YF₃:0.14Eu³⁺,0.08Gd³⁺的 激发光谱由200～300n m的宽带和Eu³⁺,Gd³⁺的系列窄带 激发峰组成。在319nm紫外光激发下,测得YF₃:xEu³⁺ 材料的发射光谱为一个多峰谱,主峰位于593,3nm。 当Eu³⁺掺杂物质的量的浓度大于14%时,出现了浓度猝灭现象。在319nm紫外光激发下,YF₃:0.14Eu³⁺, 0.08Gd³⁺的发射光谱出现Eu³⁺的⁵D₀→⁷F₁ (593nm,橙光)、⁵D₀→⁷F₂(613nm,红光)跃迁发光峰,此时,Gd³⁺ 的掺杂能增强Eu³⁺的发光。通过色坐标分析可知,当激发波长为374nm时,YF₃: 0.14Eu³⁺的色坐标为 (0.337,0.239),是很好的红色发光粉。对YF ₃:xEu³⁺和YF₃:0.14Eu3+ ,0.08G d³⁺的荧光衰减曲线的拟合证实,存在Gd³⁺→Eu³⁺的能量传递。     

Ce3+对掺Er3+碲铌锌钠玻璃光谱性质的影响

用高温熔融法制备了摩尔组分百分比为75TeO₂- 10Nb₂O₅-10ZnO-5Na₂O-0.5Er₂O₃-xCe₂O₃(x=0.00、0.25、 0.50、0.75、1.00)的碲酸盐玻璃样品。测量了玻璃样品的吸收光谱、上转换 光谱、拉曼光谱和 荧光光谱。结合Judd-Ofelt(J-O)理论计算了玻璃样品的强度参数Ω_t(t=2、4、6)、自发辐射跃迁几率A、荧光分支比β和辐射寿命 τrad,并用McCumber理论计算得到了Er³⁺的受激发射截面。比 较了玻璃样品中Er³⁺的放大器带宽 品质因子(σpeak_e×FWHM)和增 益品质因子(σpeak_e×τm),分 析了Er³⁺/Ce³⁺间能量转移(ET)机 理以及Ce³⁺对上转换发光的抑制作用。研究表明,适量Ce³⁺的引入对于掺Er ³⁺碲铌锌钠玻璃的光谱特性有一定的提高作用。     

K2MgSiO4:Eu3+红色荧光粉的制备与发光性能

采用高温固相反应合成了适合近紫外光-蓝光激 发的K₂MgSiO₄:Eu³⁺红色荧光粉,并对其发光特性进行了研究。X射线衍 射(XRD)测试结果表明,合成样品为纯相晶体。样品激发光谱由O2-→Eu³⁺电 荷迁 移带波长为(200～350nm)和Eu³⁺的特征激发峰(波长为350～500nm) 组成,主峰位于396nm波长处,次级峰位于466nm波长处。在396nm和466nm波长分别激发 下,样品发射峰均由Eu³⁺的⁵D₀→⁷FJ(J=0,1,2,3,4)能级跃迁产生,其中619nm波长处发射强度最大。 随着Eu³⁺掺杂浓度的增加,荧光粉的发光强度增大。在实验测定的浓度范 围内,未出现浓度猝灭现象。样品的色坐标位于红光区,且非常接近NTSC标准。样品发光强 度随温度增加出现温度猝灭现象,发 射峰位置并未出现明显红移。样品中,Eu³⁺在⁵D₀能 级上的荧光寿命约为0.535ms。     

YPO4:Ce3+，Tb3+反蛋白石光子晶体的制备及其发光性能的研究

本研究通过自组装法制备得到YPO₄:Ce³⁺ ,Tb³⁺ 反蛋白石光子晶体。对不同光子带隙的YPO₄:Ce³⁺,Tb³⁺的发光光谱进行研 究,可以明显的看出,反蛋白石光子晶体对⁵D₄-⁷F₅跃 迁相对于参考样品有了很明显的抑制。通过不同Tb³⁺离子掺杂浓度对发射光谱和浓度 淬 灭的研究,得出随着Tb³⁺离子浓度的不断增加其Tb³⁺离子的⁵D ₃－⁷FJ和⁵D₄－⁷FJ窄带发射强 度逐渐增大,但其⁵D₄－⁷F₅跃迁(546 nm)的 发光寿命则逐渐减少,光子晶体相对于参考样品 对Tb³⁺的浓度 淬灭抑制明显。这些发现对于进一步研究稀土发光特性以及制备新型发 光器件具有很大的指导 意义。     

用于白光LED的红色荧光粉SrAl2Si2O8:Eu3+,Li+的制备和发光性能研究

采用高温固相法制备了Sr1－x Al₂Si₂O₈:Eu³⁺ x,Li⁺0.03系列红色荧光粉,研究了试样的晶体 结构和发光性质。合成的试样均为纯相的SrAl₂Si₂O₈晶体,单斜晶系,空间群为 C2/m(12); Eu³⁺和Li⁺进入基质晶体中,使得SrAl₂Si₂O₈晶胞参数a、b和c 略微减小,只引起了晶体结构轻 微的畸变。试样的激发光谱由位于220~580nm波长的一个宽激发带 和一组锐线峰构成,其中 395nm波长处Eu³⁺的⁷F₀→⁵L₆激发峰的强度最强。发射光谱位于550~750nm波长范围内呈现多 条锐 线发射,其中595nm和615nm波长处发射峰最 强,分别归属于Eu³⁺的⁵D₀→⁷F₁磁偶极跃迁和⁵D ₀→⁷F₂电偶极跃迁。研究了Eu³⁺浓度对荧光粉发光性能的影响, 结果表明,随着Eu³⁺浓度的增 加,发光强度先增加后减小,最佳掺杂量为0.03,而对试样的色坐标 几乎没有影响;该系列荧光粉浓度淬灭机理为电偶极–电偶极(d-d)相互作用。     

非稀土红色荧光粉Mn4+:Li2TiO3发光特性研究

利用高温固相法成功合成了非稀土类红色荧光粉 Mn⁴⁺:Li₂TiO₃,并对所制得的样品进行X射线衍射(XRD)、吸收谱和荧光发射谱等 表征。在波长为475nm的LED蓝光照射时,获得了最大强度位于〖J P 〗682nm波长处的红色荧光,量 子效率约为10%,其对应Mn⁴⁺自旋²Eg→⁴A 2g。计 算了晶体场强度因子Dq和Racah参数B、C,并据此分析了Mn⁴⁺在Li₂TiO₃中的电 子云重排效应。通 过改变掺杂浓度,分析了Mn⁴⁺掺杂在Li₂TiO₃中的浓度淬灭效 应。最后进行了LED白光性能 测试。     

YPO4:Dy3+,Eu3+荧光粉的水热合成及白光发射

采用水热法,合成了YPO₄:xDy³⁺,0.06Eu³⁺系列荧光粉。通过X射线衍射(XRD )、扫 描电子显微镜(SEM)、电子散射能谱(EDS)、光致发光(PL)谱和长余辉光谱,分别对样品的物 相、结构和PL进行了表征。 XRD检测表明,合成的样品属四方晶系;荧光光谱测试表明,在234nm紫外光激发下, YPO₄:xDy³⁺,0.06Eu³⁺的 发射光谱呈现Eu3+ 的⁵D₀→⁷F₁(592nm,橙光)和 ⁵D₀→ ⁷F₂(618nm,红光) 的发光峰;而在354nm的激发波长下,YPO₄:0.06Dy³⁺,0.06Eu³⁺的发射光谱 呈现Dy³⁺的4F9/2→⁶H15/2(486nm、蓝 光)和⁴F9/2→⁶H13/2(575nm、黄光)的发光 峰,以及Eu³⁺的⁵D₀→⁷F₁(592nm、 橙光)和⁵D₀→⁷F₂(619nm、红光 )的发光峰。对荧光 衰减谱的双参数拟合证实了Dy³⁺→Eu³⁺能量 传递的存在。色坐标图显示,在234nm紫外光激发下,YPO₄:0.05Dy ³⁺,0.06Eu3+ 是很好的近紫外光激发下的白色荧光粉。     

Gd2O3:Yb3+,Er3+纳米粉体的水热合成及上转换发光研究

采用Gd₂O₃,Yb₂O₃,Er₂O₃,HNO₃,CO(NH₂)₂和C ₁₂H₂₅SO₄Na为实验原料,通过水热法合成了纳米Gd₂O₃:Yb³⁺,Er ³⁺上转换发光粉体。通过X射线衍射(XRD )、差示扫描量热 -热重分析(DSC-TGA )、傅里叶变换红外光谱(FT-IR ) 、透射电子显微镜(TEM )和 上转换发射光谱(UCL )等对样品进行表征。研究结果表明:CO(NH₂)₂与Gd ³⁺ 离子的摩尔比m影响前驱体的组成,当m=4时,前驱体是由晶态的 Gd₂(CO₃)₃·xH₂O构成。该 前驱体在空气气氛下800℃煅烧2h可获得单相的Gd₂O₃纳米粉体 ,粉体呈近球状,平均粒 径约为30～40nm。上转换发光光谱表明,在980nm波长红外光激发下,Gd₂O₃:Yb³⁺,Er³⁺的主发射峰 位于664nm波长处,呈红光发射,对应于Er³⁺的 ⁴F9/2→⁴I15/2跃迁。在波长为539 nm和562nm附近呈现绿光发射,分别对应于Er³⁺的²H11/2→⁴I15/2和⁴S3/2→⁴I15/2跃迁。Er³⁺的猝 灭浓度为1%。800℃煅烧合成的Gd₂O₃:Yb³⁺,Er³⁺ 纳米粉体的上转换发光机制为双光子模型, 而1200℃煅烧合成的Gd₂O₃:Yb³⁺,E r³⁺纳米粉体的上转换发光机制则为三光子模型。     

CaSi2O2N2:Ce3+/Eu2+荧光粉的发光性能研究

采用高温固相反应法制备了CaSi₂O₂N₂:C e³⁺/Eu ²⁺荧光粉,研究了分别掺杂Ce³⁺、Eu²⁺及Ce³⁺/Eu²⁺共掺 杂时荧光粉 的发光特性。CaSi₂O₂N₂:Ce³⁺在333 nm激发下得到宽波段的发射谱,发射峰 位于395nm,随着Ce³⁺浓度的增大,发 射波长出现明显的红移,猝灭浓度为1mol%。CaSi₂O₂N₂:Eu²⁺在397nm激发下得到峰值位于540nm处的宽波段发射谱, 猝灭浓度为1mol%。对于Ca0.99－2xSi₂O₂N₂:xCe ³⁺,xLi⁺,0.01Eu²⁺荧光粉,在333nm激发下,位于395nm处的发射峰十分微 弱,在540nm处有宽带发射,随着Ce³⁺浓度增大,位于540nm处的Eu²⁺的特征 发射显著增强。对于Ca0.98－ySi₂O₂N₂: 0.01Ce³⁺,0.01Li⁺,yEu²⁺荧光粉,在激发光波长 为333nm,Eu²⁺浓度较低时,可以观察到两个发射带,峰值分 别位于395nm及540nm,随着Eu²⁺浓度增加,位于395nm的 发射强度一直减小,而540nm处的发射强度先增加后减小,猝灭浓 度为0.4mol%。证实了Ce³⁺,Eu²⁺之间发生了有效的能 量传递。计算出Ce 3+、Eu²⁺之间能量传递的效率ηT,在Eu²⁺浓 度为 1mol%时ηT趋于饱和,达到97.7%。通过计算,得到Ce3+ 与Eu²⁺之间的能量传递方式为电偶极-电偶极相互作用。     

Er3+-Yb3+ and Er3+ doped fiberlasers

Single-mode fiber lasers operating at ~1.57 μm are described. Output powers of >2 mW are reported for laser diode pumped operation. Direct comparison is made between fiber lasers using sensitized erbium (Er³⁺ and Yb³⁺) and erbium on its own. The performance of Er³⁺-Yb³⁺ fiber lasers is analyzed in more detail as a function of fiber length. Both CW and Q-switched operations are studied and the results obtained demonstrate that practical sources at 1.5 μm are available from diode pumped Er³⁺ -Yb³⁺ systems     

Cr3+→Nd3+ energy transfer and Nd3+ laser action studies of La3Ga5SiO14:Cr3+,Nd3+ co-doped crystal

Energy transfer between Cr³⁺ and Nd³⁺ ions has been investigated in the 4.2-300-K temperature range by using steady-state and site-selective time-resolved laser spectroscopy. Radiative and nonradiative energy transfer has been studied from the time-resolved emission spectra and the donor fluorescence decays. The transfer efficiency was calculated as a function of temperature by using the Cr³⁺ lifetimes of the single doped and co-doped samples. Laser experiments were carried out in a diffusive cavity by pumping a co-doped rod 54 mm long and 5 mm in diameter with xenon flashlamps. The laser spectral emission shows a complex structure which varies as a function of pump energy. The temporal evolution of the laser spectrum is discussed in terms of a simple four-level spectral rate-equation laser model which takes into account the existence of two main broad Nd³⁺ site distributions with a large spectral overlap     

Fluorescence enhancement of single-phase red-blue emitting Ba3MgSi2O8:Eu2+,Mn2+ phosphors via Dy3+ addition for plant cultivation

Fluorescence enhancement of red and blue concurrently emitting Ba₃MgSi₂O₈:Eu²⁺,Mn²⁺ phosphors for plant cultivation has been investigated by Dy³⁺ addition. The Ba₃MgSi₂O₈:Eu²⁺,Mn²⁺,Dy³⁺(BMS-EMD) phosphors have two-color emissions at the wavelength peak values of 437 nm and 620 nm at the excitation of 350 nm. The two emission bands are coincident with the absorption spectrum for photosynthesis of plants. An obvious enhancement effect has been observed upon addition of Dy³⁺ with amount of 0.03 mol%, in which the intensities of both blue and red bands reach a maximum. The origin of red and blue emission bands is analysed. The photochromic parameters of the samples at the nearly UV excitation are tested. This fluoresence enhancement is of great significance for special solid state lighting equipment used in plant cultivation. This work has been supported by National Natural Science Foundation of China (Grant No 50872091) and the Natural Science Foundation of Tianjin, China (06YFJMJC02300, 06TXTJJC14602).     

Ho3+/Yb3+共掺的SiO2-Al2O3-BaO-BaF2微晶玻璃上转换发光研究

制备了Ho3+/Yb3+共掺的氧氟硅酸盐玻璃, 根据玻璃样品的差热分析进行微晶化处理, 测试了Ho3+/Yb3+共掺微晶玻璃的X射线衍射(XRD)图谱、吸收光谱和上转换发光光谱。结果发现, 在980 nm LD激发下, Ho3+/Yb3+共掺的含BaF2纳米晶的氧氟硅酸盐微晶玻璃可以同时观察到绿光(544 nm)和红光(656, 748 nm)上转换发光, 分别对应于Ho3+ 离子的5F4/5S2→5I8, 5F5→5I8和5F4/5S2→5I7能级跃迁, 与未热处理的玻璃样品相比, 微晶玻璃样品的绿光发光强度增强约347倍。研究结果表明含BaF2纳米晶的氧氟硅酸盐微晶玻璃是一种潜在的上转换基质材料。     

LD泵浦Er3+: Yb3+共掺全固态激光器设计

对LD泵浦Er3+:Yb3+共掺全固态激光器进行了整体设计,利用矩阵光学方法推导了高斯光束经耦合系统聚焦后束腰宽度和像距的计算公式。考虑激光棒的热透镜效应,对有源平平腔、平凹腔进行了数值计算,分析了谐振腔的稳定性。最后,根据激光谐振条件,确定了激光输出镜及滤光片的镀膜方案,为最终获得高效率、稳定的激光输出提供了理论依据。     

Infrared cross-section measurements for crystals doped withEr3+, Tm3+, and Ho3+

The absorption and emission cross sections of the transition between the ground spin-orbit multiplet and the lowest excited multiplet were measured for Er³⁺, Tm³⁺, and Ho³⁺ ions in a variety of crystalline hosts. The materials that were investigated include LiYF₄, BaY₂F₈, Y ₃Al₅O₁₂, LaF₃, KCaF₃ , YAlO₃, and La₂Be₂O₅. The absolute magnitudes of the emission cross sections were determined from the absorption spectra, with the aid of the principle of reciprocity. The calculated radiative emission lifetimes derived from these measured cross sections agree well with the measured emission decay times for most materials. The potential use of these rare-earth-doped materials in pulsed laser applications requires that the ground state exhibit adequate splitting to minimize the detrimental effects of the ground state thermal population, and also that the emission cross section be sufficiently large to permit efficient extraction energy. The systems based on Ho³⁺ in the eightfold coordinated sites of LiYF₄, BaY₂F₈, and Y₃Al₅O₁₂ appear to be the most promising     

Al3+/Eu2+共掺杂高硅氧玻璃的荧光特性

由纳米多孔玻璃制备了Al3+/Eu2+共掺杂的高硅氧玻璃,并研究了在纳米多孔玻璃基质中共掺杂Al3+离子对Eu2+离子450 nm处蓝色荧光强度和荧光峰位的影响。结果表明,共掺杂Al3+离子可分散多孔玻璃中丛聚的Eu2+离子,加之Al2O3较低的声子能量,使Eu2+离子的蓝色荧光发射显著增强;并且由于共掺杂的Al3+降低了Eu2+离子5d轨道劈裂幅度,随着Al3+离子含量的增加,Eu2+离子荧光峰蓝移。     

中频溅射技术制备镱铒共掺Al2O3光波导

在硅单晶(100)衬底上用热氧化法氧化一层SiO₂做缓冲层,在高纯铝靶上镶嵌金属Yb,Er,然后用中频磁控溅射法制备了镱铒共掺杂氧化铝薄膜。讨论了靶电压及沉积速率随氧流量的变化的磁滞回线效应,分析得出了沉积氧化物薄膜的最佳氧流量。在室温下检测到了薄膜的位于1535nm的很强的光致发光光谱(PL),并在光学掩模下用BCl₃离子束对薄膜样品进行刻蚀,得到条形光波导。     

Tuning of a Tm3+:Ho3+: silica fiber laser at2 μm

Thermal tuning of a Tm³⁺:Ho³⁺:SiO₂ glass fiber laser was investigated. As a function of fiber length and temperature, the emission wavelength can be varied between 1960 and 2032 nm. The bandwidth of the laser emission is about 2 mm. Besides the wavelength also the change of threshold and slope efficiency with temperature and fiber length and the fiber absorption were measured