Y3Al5O12:Tb3+粉体的制备及其发光特性

以AlF3和H3BO3作助熔剂,经过固相反应,在1 350℃保温4 h成功制备出结晶较好、粒度分布均匀且粒径为0.5～2.0μm的Y3Al5O12:Tb3 (YAG:Tb)单相粉末样品.通过对样品的紫外光和真空紫外光激发下的发光特性研究,发现在147 nm真空紫外光的激发下,YAG:Tb样品的真空紫外激发光谱(λem=543nm)由位于140～190nm之间的铝酸根基团吸收、O2-→Y3 电荷迁移带吸收以及Tb3 的特征吸收组成,其发射光谱由激活离子的特征发射峰构成,发光强度有明显提高.     

Er3+:Yb3+:Y3Al5O12单晶中Er3+离子光谱参数的计算

采用提拉法生长出光学质量的Er3 :Yb3 :Y3Al5O12(YAG)单晶,测定了晶体的吸收光谱和上转换荧光光谱,根据Judd-Ofelt理论,计算出Er3 在YAG晶体中的强度参数Ω2=1.074 1×10-20cm2,Ω4=1.295 3×1020cm2,Ω6=0.923 8×1020cm2.由此得到部分波段跃迁的荧光分支比、辐射寿命和积分发射截面积.提出将679 nm波段的4F9/2→4I15/2跃迁作为激光输出进一步研究的新通道.     

Yb3Al5O12激光晶体的生长

采用中频感应提拉法成功生长出Yb3Al5O12(YbAG)激光晶体.通过X射线粉末衍射分析,得出了YbAG晶体的晶胞参数a=1.193799nm,β=90°,V=1.70135nm3;密度为6.62g/cm3.测量了室温下YbAG晶体的吸收光谱和发射光谱特性.研究表明在938nm和968nm处存在Yb3+离子的2个吸收带,能与InGaAs激光二极管(LD)有效耦合,适合激光二极管泵浦;其荧光主峰位于1036nm附近,YbAG晶体的荧光寿命为270μs.     

Synthesis and Luminescence Properties of Y3Al5O（12）：Eu^（3＋） Phosphors under Vacuum Ultraviolet Excitation

采用凝胶–燃烧法合成了掺Eu3＋的Y3Al5O12（YAG：Eu3＋）荧光粉。分别采用X射线衍射（XRD）、扫描电子显微镜（SEM）、发光光谱等测试手段分析了不同温度下煅烧所得粉体的物相、形貌与发光性质。XRD和SEM结果表明：YAG：Eu3＋的最低合成温度为900℃,并且在该反应过程中没有中间相YAP（YAlO3）和YAM（YAl）的产生。1 100℃合成的晶粒尺寸比较均匀,平均粒径在90 nm左右。发光光谱的测试表明：在592 nm监控下的真空紫外激发光谱由峰值位于147、156、169nm和214nm的系列激发带组成,其分别归属于铝酸根的基质吸收以及Y3＋和Eu3＋的电荷迁移带吸收。在147nm激发下YAG：Eu3＋荧光粉最强发射峰位于592nm处,属于Eu3＋的5D0→7F1跃迁。Eu3＋在基质中的最佳掺杂摩尔分数为4%。     

Nd:Y3Al5O12透明陶瓷的超精密加工

用化学机械抛光法加工掺钕钇铝石榴石(Nd:Y3Al5O12,Nd:YAG)透明陶瓷.为了提高加工效率,在研磨阶段逐步减小B4C磨料的粒径,精密研磨和抛光阶段采用粒度为3,1 μm和0.3 μm氧化铝粉;最后,选用胶体二氧化硅作为抛光液进行化学机械抛光,以获得更好的表面光洁度.采用Wkyo激光干涉仪测量加工样品的平面度,光学显微镜观察表面宏观损伤,原子力显微镜测量表面粗糙度和微观形貌.结果表明:采用该工艺可实现高效率、高精度Nd:YAG透明陶瓷的超精密加工,加工后的Nd:YAG陶瓷表面粗糙度<0.2 nm RMS(root mean square),平面度<λ/10 (λ=633 nm),微观损伤少.     

Yb:Gd3Ga5O12多晶粉体的制备及性能表征

采用溶胶-凝胶法合成了Yb:Gd3Ga5O12(Yb:GGG)多晶粉体.利用X射线衍射、热重-差热分析、扫描电镜、红外光谱、荧光光谱测试手段,对前驱体及煅烧的粉体的结构、形貌及光谱性能进行了研究.结果表明:950 ℃煅烧的粉体已是属于体心立方的晶体结构的Yb:GGG纯相.热重-差热分析表明:Yb:GGG超细粉体的总的质量损失为29.13%,初晶化温度在830.6 ℃附近,粉体在1 246 ℃左右晶化程度较高.随着煅烧温度的提高前驱粉体粒度不断增加,形成Yb:GGG纯相的最佳的煅烧温度为950 ℃,所获得的纳米粉体粒度约为80～100 nm,粒径均匀、分散性和流动性较好.荧光光谱表明,主要发射峰位于1 030 nm,是Yb3 的基态2F7/2与激发态2F5/2能级跃迁导致的荧光发射.     

Ce3+–Eu3+共掺Y3Al5O12透明陶瓷荧光性能

Y₃Al₅O₁₂:Ce³⁺(YAG:Ce³⁺)发射谱中红光成分的不足导致了白光LED色温偏高且显色性较差,一种解决方案是引入能发射红光的激活离子与Ce³⁺共掺杂以使YAG:Ce³⁺发射谱红移。本工作报道了Ce³⁺–Eu³⁺共掺Y₃Al₅O₁₂(YAG:Ce³⁺/Eu³⁺)透明陶瓷的制备、结构和荧光性能。该材料体系在Eu含量高达25%时仍保持纯石榴石相结构,且Eu³⁺的荧光猝灭浓度高达9%左右,比Pr³⁺和Sm³⁺等离子更适合用作YAG的红光发射激活剂。YAG:Ce³⁺/Eu³⁺透明陶瓷在蓝光(如442和466 nm)激发下的Ce³⁺荧光发射随着Eu含量的...     

热处理温度对钇铝石榴石(Y3Al5O12)析晶的影响

透明YAG多晶陶瓷具有优良的光学、机械与化学性能,逐渐成为新一代固体激光基质材料.分散均匀、团聚轻、超细颗粒的纳米前驱体粉末有利于制备出高度透明的激光陶瓷.以Y2O3,Al(NO3)3·9H2O和柠檬酸为原料,采用柠檬酸-凝胶法和低温自蔓延燃烧反应相结合制备出黑色粉末,经1100℃烧结出YAG纳米前驱体粉末.采用TG-DTA,XRD,FT-IR和TEM测试手段对YAG前驱体粉末进行表征,采用谢莱公式计算出不同烧结温度下晶粒尺寸.研究结果表明:随热处理温度升高,晶粒平均尺寸增加,标准偏差以小幅度增加,晶粒尺寸分布曲线保持一致,晶格参数减小.随热处理时间增加,晶粒主要以晶界扩散形式线性长大.纳米晶粒表面原子呈不规则分布,导致晶格参数增加,前驱体颗粒由单个晶粒所构成.     

掺Nd^3＋的[Y（Ca）]3[Al（Zr）]5O12石榴石单晶光纤的生长和光谱

用激光加热基座法（ＬＨＰＧ）从粉末直接生长单晶光纤并对光谱作了研究。结果表明：ＬＨＰＧ法生长出来的单晶光纤可替代大块晶体去研究光谱等性能；Ｃａ＾２＋和Ｚｒ＾４＋等量同时掺入到Ｎｄ：ＹＡＧ晶体中，其吸收谱与Ｎｄ：ＹＡＧ基本相同，但荧光分支比和荧光衰减规律发生显著变化。此外还探讨了Ｃａ＾２＋，Ｚｒ＾４＋影响的原因。     

Nd:Gd3Ga5O12多晶原料合成及单晶生长研究

通过对晶体生长时和生长后原料挥发物的XRD分析,发现在炉膛内壁上的挥发物质是Ga2O3和Ga2O的混合物,而观察窗口及后加热器内壁上的挥发物主要是Gd2O3。为避免原料中Ga2O3的挥发,按化学计量比配料,在1300℃下,采用固相反应法合成了Nd：Gd3Ga5O12(Nd：GGG)多晶原料。用此多晶原料,采用提拉法进行了Nd：GGG单晶生长研究,所获单晶的荧光发射峰位于1061．54nm。对晶体表面的开裂现象进行了分析。     

Density measurements of molten Y3Al5O12 and Y2O3-Al2O3 compounds using an electrostatic levitation technique

The densities of molten Y₂O₃-Al₂O₃ compounds, including yttrium aluminum garnet (Y₃Al₅O₁₂), were determined over a wide temperature range that included an undercooled region, using an electrostatic levitation furnace. The density of the molten Y₃Al₅O₁₂ varied with temperature according to the relationship 3750 − 0.25(T − T_m) (kg/m³) with T_m = 2240 K and for the range of 1300 K ≤ T ≤ T_m, yielding the thermal expansion coefficient ɑ = 6.7×10⁻⁵ K⁻¹. The molar volumes of molten (100-x)Y₂O₃-xAl₂O₃ (x = 0, 33.3, 50, 55, 62.5, 76.5, 81.5, or 100 mol%) were found to vary with the value of x in a linear manner within the superheated temperature range. However, the molar volumes in the undercooled region deviated from those calculated using an ideal solution model owing to attractive interactions between Y₂O₃ and Al₂O₃.     

Kinetic effects of substitution Er3+ for Y3+ in (Y1-xErx)3Al5O12 garnet

The crystallization kinetics of erbium-substituted yttrium aluminum garnet (Er:YAG) from the amorphous phase was studied depending on the degree of substitution of yttrium by erbium: (Y_1-xEr_x)₃Al₅O₁₂, x = 0 – 0.9. The corresponding series of nanopowders were synthesized using the sol-gel method with binary sols as the starting materials. Crystallized single-phase Er:YAG powders were obtained at temperatures as low as 1370 K through the formation of intermediate phases. The crystallization kinetics of the Er:YAG precursors was analyzed using non-isothermal differential scanning calorimetry and X-ray diffraction analysis. The proposed unified crystallization model, based on which the kinetic parameters of the crystallization process of the Er:YAG from the amorphous phase were determined, depending on the content of erbium oxide. Time-temperature-transformation curves were developed from the obtained data to determine the optimal modes in the heat treatment and sintering of optical ceramics. Er:YAG transparent ceramics were obtained by vacuum sintering of sol-gel powders.     

柠檬酸凝胶法制备Er,Tm∶Yb3Al5O12纳米粉体及发光性能

以柠檬酸为燃烧剂,采用柠檬酸凝胶法制备了Er,Tm∶Yb3Al5O12(Er,Tm:YbAG)纳米粉体,其最佳的制备工艺条件:Er3+和Tm3+掺杂的摩尔分数分别为2%和1%,柠檬酸与金属硝酸盐原子总数的摩尔比为1.7∶1,煅烧温度和时间分别为950℃和2h。制备的粉体颗粒为规则球形,粒径均匀、分散性好,平均粒径约为45nm。研究了样品的发光性能,结果表明:2%Er,1%Tm∶YbAG样品的发光性能最好,在1 587、1 658和1 711nm处有较强发射峰,分别对应Er3+的4 I13/2→4 I15/2跃迁和Tm3+的3 F4→3 H6跃迁。样品的上转换光谱表明,上转换荧光峰包括了蓝光、绿光和红光。     

掺钕钆镓石榴石晶体的激光性能

采用提拉法生长了Nd：Gd3Ga3O12（Nd：GGG）晶体。切割后的样品经过端面抛光,测试了荧光光谱、吸收光谱和激光性能。荧光光谱表明：晶体的最强的荧光发射峰位于1062nm,是Nd^3＋的4^F3/2-4^I11/2谱项导致的荧光发射。由吸收光谱发现：Nd：GGG晶体的最强吸收峰位于808nm,表明该晶体适合于激光二极管泵浦．并且吸收峰强度随掺杂离子浓度的增加而增加。激光性能测试结果表明：激光二极管泵浦时光-光转换效率为33.＋8％,斜效率为57.8％。     

溶胶-凝胶法合成钇铁石榴石(YIG)的凝胶化及热处理研究

采用溶胶-凝胶法制备了YIG纳米晶粉体材料，分析了合成条件（pH值、浓度、反应温度和反应时间）以及热处理等影响材料合成的主要参数，利用DTA，TGA，XRD，TEM等手段对材料的制备过程和产物进行了分析，探讨材料制备最适宜的工艺条件，着重研究了热处理工艺对YIG的晶相和颗粒尺度等物理特性的影响，实验结果表明，YIG相的形成是一个放热温度始于500℃，峰位于759℃的缓缓的放热过程，且样品平均晶粒尺寸随热处理呈规律性变化，因此可以通过采用溶胶-凝胶法及适当的热处理条件在较低的温度下制备单相YIG纳米粉体材料。     

A far-red-emitting (Gd,Y)3(Ga,Al)5O12:Mn2+ ceramic phosphor with enhanced thermal stability for plant cultivation

As for plants, far-red (FR) light with wavelength from 700 nm to 740 nm is critical for processes of photosynthesis and photomorphogenesis. Light-controlled development depends on light to control cell differentiation, structural and functional changes, and finally converge into the formation of tissues and organs. Phosphor converted FR emission under LED excitation is a cost-effective and high-efficient way to provide artificial FR light source. With the aim to develop an efficient FR phosphor that can promote the plant growth, a series of gadolinium yttrium gallium garnet (GYGAG) transparent ceramic phosphors co-doped with Mn²⁺ and Si⁴⁺ have been fabricated via chemical co-precipitation method, followed sintered in O₂ and hot isostatic pressing in this work. Under UV excitation, the phosphor exhibited two bright and broadband red emission spectra due to Mn²⁺: ⁴T₁ → ⁶A₁ spin-forbidden transition, and one of which located in the right FR region. And then, Ce³⁺ ions were co-doped as the activator to enhance the absorption at blue light region and the emission of Mn²⁺. It turns out that the emission band of GYGAG transparent ceramic phosphors matches well with the absorption band of phytochrome P_FR, which means they are promising to be applied in plant cultivation light-emitting diodes (LEDs) for modulating plant growth. Besides, the thermal stability of this material was investigated systematically, and an energy transferring model involves defects was also proposed to explain the phenomenon of abnormal temperature quenching.     

LED白光照明用(Y0.98-xSrx)3Al5O12:Ce0.06和(Y0.98-xBax)3Al5O12:Ce0.06系列荧光粉的晶相与荧光光谱

本研究采用较温和的高温固相法,用碱土金属离子Sr2+和Ba2+取代Y3+离子进行基质取代,合成了一系列(Y0.98-xSr)3Al5O12:Ce0.06和(Y0.98-xBax)3Al5O12:Ce0.06荧光粉.运用XRD对荧光粉进行了表征,试验结果表明:在一定的掺杂取代范围内,这些体系具有立方石榴石结构.运用荧光光...