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.     

Yb3+:Gd3Ga5O12激光晶体原料合成与生长的研究

采用溶胶-凝胶法合成了Yb：GGG多晶料.以XRD分析方法对合成料的前驱体及烧成的粉体的相结构进行了研究,XRD分析结果表明,950 ℃煅烧的粉体已是Yb:GGG纯相.采用提拉法,通过设计合理而稳定的温场、选择最佳工艺参数等生长了Yb:GGG晶体.荧光光谱测试结果表明,Yb:GGG晶体主要发射峰位于1030 nm,该荧光是由Yb3+激发态2F5/2向基态2F7/2能级跃迁产生的.     

柠檬酸凝胶燃烧法制备Nd,Yb∶YGG激光陶瓷粉体及表征

以Nd2 O3、Yb2 O3、Y2 O3、Ga2 O3和柠檬酸为原料,采用凝胶燃烧法,制备出Nd,Yb∶ YGG激光陶瓷粉体.对粉体进行XRD测试,结果表明在本实验条件下,粉体的较佳煅烧温度为800℃.扫描电镜观察发现,粉体晶粒为类球形,平均晶粒径约为50 nm,晶粒间存在一定烧结现象.荧光光谱测试结果表明Nd,Yb∶ YGG激光陶瓷粉体最强发射峰位于1028 nm,归属于yb3的2 F5n→2 F7n能级跃迁,并且当Nd3+和yb3+的摩尔比为1∶1时yb3的荧光发射强度最强.     

柠檬酸凝胶燃烧法制备Nd3+,Yb3+:Y2O3多晶原料及其相组成和荧光特性的研究

本文采用柠檬酸凝胶燃烧法合成了性能优良的Nd3+,Yb3+:Y2O3多晶原料。XRD、IR和SEM测试结果表明样品在900℃煅烧可获得纯相的Nd3+,Yb3+:Y2O3,平均粒径约为40 nm;TG-DTA测试结果表明样品在30～600℃之间失重约为49.28%;从荧光光谱上可以看出两个主要发射峰位于970～1100 nm之间,最强发射峰位于1030nm,对应Yb3+的2F5/2→2F7/2能级跃迁。     

Gd2O3:Eu荧光粉体的制备及其发光特性

分别采用溶胶-凝胶/燃烧合成结合法和共沉淀法合成了Gd2O3:Eu粉体,借助X射线衍射、扫描电镜、透射电镜、分光光度计等分析手段,对比研究了两种工艺制备Gd2O3:Eu荧光粉体的物相组成、形貌及荧光特性.结果表明:共沉淀法合成的Gd2O3:Eu为立方相;溶胶-凝胶/燃烧合成法制备的Gd2O3:Eu为单斜相.溶胶-凝胶/燃烧合成法制备的Gd2O2:Eu粉体蓬松、多孔,但存在一定程度的团聚.共沉淀法制备的立方相Gd2O3:Eu粉体在610 nm处呈现Eu2 的特征荧光;溶胶-凝胶/燃烧合成法制备的单斜相Gd2O3:Eu的发射波长产生红移,其中最强的2个发射峰起源于Eu3 的5D0→7F2跃迁,分别位于612 nm和621 nm.两种工艺制备Gd2O3:Eu粉体荧光特性的差异是由Eu3 在这两种粉体中所处晶格结构的对称性差异引起的.     

溶胶-凝胶低温燃烧法制备Yb,Ho∶Gd_3Ga_5O_(12)纳米粉体

采用溶胶-凝胶低温燃烧法制得了Yb,Ho∶GGG纳米粉体。X射线衍射分析结果表明900℃煅烧得结晶良好的Yb,Ho∶GGG纯相。IR光谱分析发现900℃煅烧的样品在617 cm-1附近出现一系列GGG的晶格振动吸收峰。SEM观察发现Yb,Ho∶GGG纳米粉体粒径在20 nm左右,粒度均匀,无团聚。荧光光谱分析表明样品的最强发射峰位于1200 nm,是由Ho3+的5I6-5I8能级跃迁引起的荧光发射,且发现Yb3+-Ho3+间存在能量传递。     

Yb:YVO4多晶粉体的合成与性能表征

采用液相共沉淀法合成了Yb:YVO4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,对前驱体及煅烧粉体的结构、形貌及光谱性能进行了研究.结果表明:粉末样品的衍射峰的分布和相对强度与标准YVO4的基本一致.热重分析表明,1 000℃煅烧时,Yb:YVO4粉体总质量损失为13.59%,随着煅烧温度的提高,前驱粉体颗粒尺寸不断增加.800℃煅烧后的粉体为纳米级Yb:YVO4纯相粉体,1000℃煅烧后的粉体粒度约170nm、粒径均匀、分散性和流动性好.荧光光谱表明:主要发射峰位于1 025.76nm,是Yb3 的基态2F7/2与激发态2F5/2能级跃迁导致的荧光发射.     

用液相沉淀法或固相法合成Nd:GGG粉体并制备透明陶瓷

比较了用液相沉淀法或固相法合成的粉体以及最终制得的掺钕钆镓石榴石(neodymium-doped gadolinium gallium garnet,Nd:GGG)陶瓷的性能.结果表明:液相法合成的粉体粒度均匀、粒径小,经干压成型后、在1 650℃低真空(1.1×103Pa)状态下烧结2～3h得到一定透明度的Nd:GGG陶瓷.用固相法制备的粉体成型后、在1 750℃烧结2～3 h得到的Nd:GGG陶瓷完全不透明.测得半透明的Nd:GGG陶瓷的吸收光谱和荧光光谱,计算出807nm的峰值吸收截面为1.0×10-20cm2,最强发射峰在1061nm.     

钕镱共掺钇铝石榴石纳米粉体

采用溶胶-凝胶燃烧法,制备了钕镱共掺钇铝石榴石(Nd3+/Yb3+:YAG)透明陶瓷纳米粉体,并用热分析、X射线衍射、红外光谱、透射电镜、吸收及荧光光谱等测试方法对其结构、形貌及性能进行分析.结果表明:经900℃煅烧,Nd3+/YB3+:YAG透明陶瓷的质量损失为49.56%,所得到的Nd3+:Yb3+:YAG纳米粉体结晶好,烧结性好,纯度较高,形状规则,粒径均匀,均在60～100衄之间.在808 nm处具有较强的吸收带,对应于Nd离子4I9/2-4F7/2跃迁,有利于对808nm激光二级管泵浦光的吸收.在1064nm处,Nd3+/Yb3+:YAG的发射峰要强于Nd3+:YAG,说明在Nd3+/Yb3+:YAG中,通过[(4F3/2)Nd),(2F7/2)Yb]→[(4I9/2)nd,(2F5/2)Yb]离子问的交叉弛豫,产生了有效的Yb3+到Nd3+的能量转移,从而实现激光的高效输出.     

Er3+,Yb3+:YGG激光陶瓷粉体制备与性能研究

本文以Y2O3,Ga2O3,Er2O3,Yb2O3,柠檬酸为原料,利用溶胶-凝胶法制备出Er3+,Yb3+∶YGG激光陶瓷前驱粉体.对粉体进行XRD测试,结果表明在本实验条件下,粉体的最佳煅烧温度为800℃.红外光谱表明800℃时NO;,OH-等离子已被分解.扫描电镜观察发现,粉体颗粒为似球形,粒径约为35 nm,结合XRD数据计算,发现一个颗粒由2～3个晶粒组成,可见溶胶-凝胶法制备的粉体团聚程度相对较低.对粉体进行荧光光谱测试,结果表明由于Er3+的4I13/2-4I15/2的能级跃迁引起的荧光发射,其最强峰位于1530nm处.     

Effect of Yb doping concentration on crystallization kinetics in yttrium aluminum garnet nano-powders

Different ytterbium concentration–doped yttrium aluminum garnet (Yb:YAG) nanopowders were synthesized using coprecipitation with nitrate salts as the starting materials. The phase evolutions, morphologies, and microstructures of the powders synthesized from various ytterbium-doped precursors were investigated. Ytterbium doping concentration was discovered to have a crucial effect during the YAG phase formation from the precursor. Crystallized Yb:YAG powders were directly obtained at temperatures as low as 900 °C without the formation of any intermediate phase. The crystallization kinetics of the Yb:YAG precursors were analyzed using non-isothermal differential scanning calorimetry. Avarami parameters of 0.97, 1.00, 1.13, and 1.21 were obtained for Yb doping concentrations of 0, 3, 6, and 9 at% respectively, and crystallization activation energies of 1506±40, 1342±36, 1171±31, and 978.1±26 kJ/mol were calculated. The activation energy for YAG crystallization was lower when a high Yb doping concentration was used because the presence of Yb³⁺ prohibited the presence of anionic SO₄²⁻ in the precursors, thus enhancing the elemental diffusion between particles. Both the average grain size and particle size of Yb: YAG decreased when Yb doping concentration was increased, and at various calcination temperatures.     

Optical properties of Er,Yb co-doped YAG transparent ceramics

The transparent polycrystalline erbium and ytterbium co-doped yttrium aluminum garnet (Er,Yb:YAG) ceramics with various Yb contents from 5% to 25% were prepared by the solid-state reaction and the vacuum-sintering technique. The in-line transmittances of the mirror-polished ceramics exceed 80% from the visible band to the infrared band. The samples are very compact with few pores. The average grain size of the Er,Yb:YAG ceramic is about 15 μm. The upconversion luminescence spectra, infrared luminescence spectra and luminescence decay curves of the ceramics were observed and discussed. For 1%Er doped YAG ceramic, the best ion ratio of Yb³⁺ and Er³⁺ is around 15:1.     

Ho3+:Yb3+:KLa(WO4)2激光晶体生长与性能

以K2W2O7为助熔剂,采用泡生法生长钬镱双掺钨酸镧钾[Ho3 :Yb3 :KLa(WO4)2,Ho:Yb:KLW]晶体.通过热重-差热分析,确定晶体的熔点为1 118 ℃,在熔点以下晶体没有相变,热稳定性很好.X射线衍射分析表明:所生长的晶体为四方晶系Ho:Yb:KLW晶体,晶胞参数为a =b =0.538 nm,c =1.193 nm.测量晶体的红外及Raman光谱,并对峰值进行了归属.晶体样品的吸收光谱显示:Yb3 在978 nm处吸收峰较强,半峰宽为19 nm,适合采用InGaAs半导体激光二极管来作为激励源.表明Yb3 对Ho3 具有敏化作用.     

用纳米粉制备Nd:Y1.84La0.16O3透明陶瓷

用碳酸盐共沉淀法制备一种新的掺钕氧化镧钇(Nd:Y1.84La0.16O3)纳米粉体,得到颗粒细小、均匀、分散性好、粒径为50～60nm的Nd:Y1.84La0.16O3纳米粉体.分别采用Nd:Y1.84La0.16O3纳米粉料和商业粉料,用传统陶瓷无压烧结工艺制备Nd:Y1.84La0.16O3透明陶瓷.Nd:Y1.8vLa0.16O3纳米粉制备的陶瓷样品的组分均匀、几乎不存在第二相,具有较高的透过率.商业粉制备的陶瓷样品因混料不均匀而在晶界处存在部分第二相,降低了陶瓷的透过率.此外,还运用体视学法预测了2种陶瓷透过率的相对高低,分析了三维结构参数对陶瓷光学性能的影响.     

Probing structure of ytterbium stabilized Pr-doped zirconia obtained by microwave hydrothermal method

Nanoparticles of ZrO₂:Pr stabilized with ytterbium in the range 0.5%mol.-20%mol. were synthesized. Crystallite sizes depended on Yb concentration. Red luminescence resulting from ¹D₂→³H₄ transition of Pr³⁺ is present in all the samples. Additionally in the samples calcined at 1200 °C blue-green luminescence from ³P₀ level of Pr³⁺ was found. This emission was more intense than red one. Intensity of the ³P₀→³H₄ luminescence depended on ytterbium content and was found to be the highest at 20% mol. Yb. Luminescence study had shown, that ytterbium introduced additional lattice defects. Some quantity of praseodymium activator ions were found to be present at +4 state and changed its valence to +3 as ytterbium content had risen.     

Thermal Properties of Transparent Yb‐Doped YAG Ceramics at Elevated Temperatures

This work presents the thermal properties of ytterbium‐doped yttrium aluminium garnet (Yb:YAG) transparent ceramics at elevated temperatures in dependence on the dopant concentration and on temperature. Transparent polycrystalline Yb:YAG ceramics were prepared by solid‐state reaction of oxide powders sintered under high vacuum. The dopant amount varied from 0 to 20 at.% of Yb. Thermal diffusivity of the sintered samples was measured by the laser and xenon flash methods at temperatures ranging from room temperature to 900°C. Both the thermal diffusivity and thermal conductivity values decreased with increasing dopant content, and until 500°C a decrease was observed also with increasing temperature. When available, the measured values were compared to data published in literature, and were found to be in good agreement. Based on the measured values, empirical relations in the form of shifted power laws are proposed for the temperature dependence of thermal diffusivity.     

水热法合成ATO纳米粉体的研究

以SnCl4·5H2O和SbCl3为锡源和锑源,采用水热法制备锑掺杂氧化锡（ATO）纳米粉体,分析了锑掺杂量、水热时间、水热温度对ATO纳米粉体的影响。研究结果表明：在180℃的温度下水热反应16 h后,Sb元素全部固溶进SnO2的晶格,且分布比较均匀,ATO颗粒径在10 nm左右;粉体的晶粒径随锑掺杂量的增加而逐渐减小,但随水热时间的延长而逐渐增大;随着水热温度的升高,所得粉体由无定形向晶形转变,粉体的结晶性变好。     

Mixed oxidation states of Yb and Sm in Si-Al-O-N glasses

The mechanical and optical properties of samarium and ytterbium doped Y-Si-Al-O-N glasses have been studied. It has been shown that both samarium and ytterbium undergo a reduction from the trivalent state in the raw materials to the divalent state in the glass, the degree of conversion depending on the melting time. Emission spectra of samarium containing glasses show the presence of both Sm³⁺ as well as that of Sm²⁺, which is also reflected by the Young's modulus and density. A broad absorption band of Yb²⁺ characterizes the reflection spectra of ytterbium containing glasses, indicating a similar reduction, while a second absorption band suggests the presence of some remnant Yb³⁺. The other properties of these glasses also appear to confirm a mixed oxidation state of Yb. These reductions have been attributed to the reducing power of chemically incorporated nitrogen (N³⁻) in the glass matrix, as demonstrated earlier for Eu-Si-Al-O-N glasses.     

Y2O2S:Yb,Ho上转换发光材料的制备及性能

利用硫熔法制备了不同浓度的Yb和Ho掺杂的Y2O2S:Yb,Ho上转换发光材料。采用X线衍射仪、扫描电镜和荧光光谱仪对粉体的相组成、形貌和上转换发光性能进行表征。结果表明:不同浓度的Yb和Ho掺杂后没有改变Y2O2S的晶体结构;颗粒形貌较为规则,多呈现多面体状,分散性较好,颗粒表面很光滑;在980nm激光激发下,Y2O2S:Yb,Ho呈现出以绿光发射为主的上转换荧光,Yb的最佳掺杂量为8%(摩尔分数),Ho的最佳掺杂量为2%(摩尔分数),Ho3+和Yb3+掺杂浓度可显著影响不同颜色发射峰的强度;对激活离子Ho3+来说,同类离子之间发生能量传递和交叉弛豫行为,导致上转换荧光强度发生猝灭;对敏化离子Yb3+来说,Yb3+吸收能量,以热的形式释放出来,产生杂质猝灭。     

Nd:GGG晶体生长、光谱性能及激光性能

采用提拉法生长掺钕钆镓石榴石(neodymium-doped gadolinium gallium garnet, Nd: GGG)激光晶体,选择最佳工艺参数:提拉速率为2～4mm/h:转速为20～40r/min;冷却速率为20℃/h.测试了晶体的吸收和荧光光谱,结果表明:主吸收峰位于808nm,主发射峰位于9430cm-1,对应于Nd3 的4F3/1-4I11/2跃迁.对晶体样品进行了激光性能测试.结果表明:当泵浦功率为900mW时,对泵浦光的吸收效率为85%,激光输出波长约为1μm,激光输出功率为305mW,激光阈值功率为380mW,光-光转换效率达57.8%,斜效率达57.6%.