Er,Yb:(LaGd)_2O_3纳米粉体的制备与发光性质

以碳酸氢铵为沉淀剂,采用共沉淀法制备了Er,Yb:(La Gd)2O3纳米粉体。经1 000℃煅烧2 h得到的粉体颗粒呈规则球形,平均粒径约为90 nm,团聚低,分布均匀。研究了Er3+,Yb3+的掺杂量对样品发光强度的影响。结果表明:掺杂Er3+和Yb3+的摩尔分数分别为4%和5%时,所得样品的发光性能最优。样品的激发和发射光谱显示:在379 nm处激发峰最强,对应Er3+的4I15/2→4G11/2能级跃迁;最强发射峰位于562 nm处,对应于4S3/2/2H11/2→4I15/2能级跃迁。样品的上转换光谱表明:样品在548和662 nm有较强的发射峰,对应Er3+的4S3/2/2H11/2→4I15/2跃迁和4F9/2→4I15/2跃迁。并讨论了发光跃迁机制。     

NaY(WO4)2:Dy3+荧光粉的制备及其上转换发光性能

利用水热法合成了NaY(WO4)2:Dy3+上转换荧光粉. 通过XRD、SEM表征该荧光粉结构和形貌. 探讨了Dy3+浓度、pH值、反应温度及焙烧温度对NaY(WO4)2:Dy3+晶体结构、形貌及发光性能的影响,得到在Dy3+浓度为0.5%,pH=8,反应温度180℃,800℃焙烧条件下的样品具有最佳上转换发光性能. 利用776 nm近红外光激发NaY(WO4)2:Dy3+,观察到480 nm处的蓝光发射峰以及577 nm处的黄光发射峰. 其中蓝光来自Dy3+离子的4F9/2→6H15/2跃迁,黄光由Dy3+离子4F9/2→6H13/2跃迁产生.     

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。     

In∶Yb∶Er∶LiNbO_3晶体的生长和光谱性能

采用提拉法生长了掺0.25%(摩尔分数,下同)Yb2O3,0.25%Er2O3和(0.5%、1.0%、1.5%)In2O3的3种同成分In∶Yb∶Er∶LiNbO3晶体。通过晶体的红外光谱,解释了In3+,Yb3+和Er3+在晶体中的占位,由于Yb3+和Er3+离子的掺入,在In∶Yb∶Er∶LiNbO3晶体中In3+既占据Li位又部分占据Nb位,使2%In∶Yb∶Er∶LiNbO3晶体达到阈值浓度。采用980nm二极管激光器测试了In∶Yb∶Er∶LiNbO3晶体上转换发射光谱。结果表明:晶体的绿光上转换发射中心波段位于525、550nm处,分别相应于Er3+的2 H11/2→4 I15/2跃迁和4 S3/2→4 I15/2跃迁;上转换红光发射中心波段在660nm处,对应Er3+的4 F9/2→4 I15/2辐射跃迁。In3+能提高Yb∶Er∶LiNbO3晶体的抗光损伤能力,改变Er3+和Yb3+的局部环境及Yb3+对Er3+的敏化作用,使得In∶Yb∶Er∶LiNbO3晶体发光性能改变。     

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。     

GdF3∶Eu3+和NaGdF4∶Eu3+发光粉的可控合成与发光性质

采用聚乙烯吡咯烷酮(PVP)辅助水热法合成了GdF3∶Eu3+和NaGdF4∶Eu3+发光粉。利用X射线衍射(XRD)、扫描电子显微镜和荧光光谱对样品的结构、形貌和发光性能进行了研究。XRD分析表明:GdF3晶相到NaGdF4晶相的转换可以通过改变初始溶液pH值、PVP加入量和NaF与稀土离子(Gd3+和Eu3+)摩尔配比等合成条件实现。NaGdF4∶Eu3+发光粉的形貌受合成条件的影响。荧光光谱研究表明:GdF3∶Eu3+发光粉主发射峰位于593nm处,来自于Eu3+的5 D0→7 F1磁偶极跃迁;NaGdF4∶Eu3+发光粉主发射峰位于616nm,来自于Eu3+的5 D0→7 F2电偶极跃迁。2个样品中Gd3+与Eu3+离子之间存在较好的能量传递,而NaGdF4晶格更有利于2种离子的能量传递。     

Li2SrSiO4:Eu2+,Tb3+中Eu2+和Tb3+的发光特性和能量传递

用高温固相法在N2/H2=95/5(v/v)还原气氛下合成了Li2SrSiO4:Eu2+,Tb3+荧光粉发光材料,通过荧光光谱研究其发光特性,并从理论上探讨了Eu2+与Tb3+之间的能量转移类型。结果表明:该发光材料主发射峰值550nm,与Eu2+在4f7-4f65d1产生跃迁有关;通过掺杂,共存于Li2SrSiO4基质中的Tb3+通过电多级相互作用将能量传递给Eu2+;在500~650nm范围内对Eu2+具有很强的敏化作用,使其在主发射峰550nm的发射强度显著增强;当名义化学组成为Li2Sr0.995SiO4:0.005Eu2+,0.010Tb3+时,发光强度为最佳。     

红色荧光粉Ba2–xB2O5:xSm3+的制备及发光性能

采用高温固相法合成了Ba2–xB2O5:xSm3+红色荧光粉。研究了Sm3+掺杂量对样品发光性质的影响。结果表明,合成物质为纯相Ba2B2O5晶体结构。主激发峰为342nm(6H5/2→4H9/2)、359nm(6H5/2→4D3/2)、372nm(6H5/2→6P7/2)、400nm(6H5/2→4F7/2)、436nm(6H5/2→4G9/2)、450～510nm(6H5/2→4I13/2,4I9/2,4I11/2,4G7/2)。主发射为550～575nm(4G5/2→6H5/2)、580～620nm(4G5/2→6H7/2)及630～660nm(4G5/2→6H9/2),其中以400nm激发的峰值最大。随着Sm3+掺量x的增大,发光强度先增大后减小,在x=0.06时达到最大值。分析表明其浓度猝灭的机理是电偶极–电四极相互作用。     

LaF_3:Yb/Er@NaYF_4纳米颗粒的热分解法合成与上转换发光性能研究

采用热分解法以十八烯和油酸作为反应的溶剂,制备了La F3:Yb/Er@Na YF4上转换纳米颗粒。X-射线衍射(XRD)结果表明:所合成的核纳米颗粒为立方相La F3:Yb/Er,La F3:Yb/Er@Na YF4与立方相Na YF4完全对应,且包覆后的平均粒径约为15 nm。透射电子显微镜(TEM)结果表明:样品具有明显的核壳结构,具有单分散性,且形貌均一、结晶性高;在980 nm近红外光激发下,荧光光谱中波长在524 nm和543 nm附近发出来自于Er3+的2H11/2→4I15/2的绿光和4S3/2→4I15/2的黄光,664 nm附近发出来自于Er3+的4F9/2→4I15/2的红光。利用Lg Iem∝Lg Inex公式对发光带峰面积随激发光功率变化的数据进行拟合,证明该样品属于双光子能量吸收过程。     

不同波长响应的Y2O2S:Er3+,Yb3+上转换发光材料的光谱特性

以Y2O2S为基质材料、Er2O3为激活剂、Yb2O3为敏化剂,采用固相反应法制备Y2O2S:Er3+,Yb3+上转换发光材料.采用X射线粉末衍射分析和荧光光谱分析表征样品的结构和发光性能,并分析上转换发光机理.结果表明:在980 nm和1 550 nm红外光激发下,样品发出源于Er3+的2H11/2→4I15/2、4...     

Er3+,Er3+-Yb3+和Er3+-Na+掺杂CaF2透明陶瓷的光学性能

以Ca(NO3)2、Er(NO3)3、Yb(NO3)3、KF和NaF为原料,采用热压烧结方法制备出Er3+,Er3+-Yb3+和Er3+-Na+掺杂CaF2透明陶瓷。测试了样品室温吸收光谱和发射光谱。利用Judd-Ofelt理论分析了样品的光学性能,并对吸收光谱进行计算拟合,得到光谱参数?t (t=2,4,6),根据光谱参数?t计算出Er3+某些能级的的跃迁几率、荧光分支比、辐射寿命和品质因子,讨论并比较了Er3+-Yb3+和Er3+-Na+共掺对CaF2透明陶瓷光学性能的影响。结果表明：掺杂Yb3+和Na+改变了Er3+光谱参数;Er3+-Yb3+共掺有利于提高样品的荧光强度;Er3+-Na+共掺有利于提高荧光寿命。     

PMBP和TTA协萃剂负载泡沫塑料萃取Sc~(3+)、Y~(3+)、Nd~(3+)、Er~(3+)的性能研究

论述了将ＰＭＢＰ和ＴＴＡ协萃剂负载于聚醚型聚氨酯泡沫塑料上,萃取微量稀土元素钪、钇、钕、铒的最佳实验条件（萃取剂浓度、温度、酸度）。研究了它们的萃取性能（萃取百分率、分配比、萃取容量）。说明这是可行的萃取方法。     

Eu^3＋、Dy^3＋对CaTiO3：Pr^3＋红色磷光体发光性能的影响

采用改进高温固相法合成了掺杂Eu3+和Dy3+作为共激活离子的红色长余辉磷光体,详细阐述了Eu3+、Dy3+对CaTiO3:Pr3+红色磷光体发光性能的影响.通过X-射线衍射仪和电子扫描显微镜对所得样品的晶相类型及表面形态进行了表征,结果发现,在一定灼烧温度下,Eu3+或/和Dy3+对晶相的作用是协同的,且Eu3+或/和Dy3+对CaTiO3:Pr3+红色磷光体的粒径也有影响.室温条件下采用荧光/磷光发光光度计对其发光性能进行测定,结果表明,一定量的Eu3+或/和Dy3+能显著改善CaTiO3:Pr3+红色磷光体的发光性能.     

十二烷基磺酸根插层Ni~(2+)-Fe~(3+)/Co~(2+)-Ni~(2+)-Fe~(3+) LDHs及其结构研究

应用水热技术制备了二元Ni2+-Fe3+-CO23- LDHs和三元Co2+-Ni2+-Fe3+-CO32- LDHs,以十二烷基磺酸根离子作为插层客体,通过离子交换反应在酸性溶液中实现了十二烷基磺酸根插层Ni2+-Fe3+ LDHs和Co2+-Ni2+-Fe3+-LDHs。十二烷基磺酸根在Ni2+-Fe3+LDHs层间出现了2种空间导向和排列:即十二烷基磺酸根以单层垂直方向排布和以双层垂直方向排布在层间;十二烷基磺酸根在三元组分Co2+-Ni2+-Fe3+-LDHs层间只有一种空间排列方式,即十二烷基磺酸根以单层垂直方向排布于Co2+-Ni2+-Fe3+-LDHs层间。     

Photoluminescence analysis of Sm3+ and DY3+ doped PVA films

A couple of Poly vinyl alcohol (PVA) films with Sm³⁺ and Dy³⁺ ions have been prepared by a conventional solution cast technique. For these Sm³⁺ and Dy³⁺ doped PVA films, Fourier transform infrared and also absorption spectral measurements have been carried out. Excitation and emission spectra and decay curves have been recorded to understand emission performance of the polymers namely Sm³⁺: PVA film with λ_exci = 400 nm and Dy³⁺: PVA film with λ_exci = 349 nm. Emission performances of these films have been explained in terms of relevant energy level schemes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

3D打印多通道微反应器用于萃取分离In3+和Fe3+

将微流体萃取技术与新兴的3D打印技术相结合，设计并制造了一种结构较为复杂的多通道微流体萃取反应器，通过在微反应器内增加混合反应通道的数目来放大其处理量，以期使3D打印多通道微反应器在能够继承微流体单级萃取效率高优点的同时，也能够极大地扩大其处理量。反应器的结构特征主要包括两相入口、液滴筛板、混合萃取通道、混合液汇集腔及混合液出口等。将此种反应器用于不同初始条件下从硫酸溶液中萃取和分离In³⁺和Fe³⁺的实验，结果表明：随着两相接触时间的增长，萃取剂P204对于金属离子的萃取率呈现出先减小，再增大的趋势；溶液中In³⁺和Fe³⁺的分离系数在pH为0.7、接触时间为90s、萃取剂体积分数为30%时，达到最高值381.9。对初始溶液pH、萃取剂在油相中的体积分数、两相的接触时间等单因素对In³⁺和Fe³⁺的萃取率和分离系数的影响作了详细调查。     

Enhanced luminescence properties and energy transfer in Ce3+ and Tb3+ co-doped NaCaBO3 phosphor

A series of color-tunable NaCaBO₃: Ce³⁺, Tb³⁺ phosphors have been synthesized on the basis of efficient Ce³⁺→Tb³⁺ energy transfer. The photoluminescence emission and excitation spectra, the lifetime, and the effect of Tb³⁺ concentration are investigated in detail. The enhanced photoluminescence of Tb³⁺ with sharp emission lines could be obtained by the broad excitation band from the allowed 4f–5d absorption of Ce³⁺ ions. The intensity ratio of blue emission from Ce³⁺ and green emission from Tb³⁺ can be tuned by adjusting their concentrations. The energy transfer from Ce³⁺ to Tb³⁺ in NaCaBO₃ was found to be an electric dipole–quadrupole interaction.     

Thermoelectric properties of La3+ and Ce3+ co-doped CaMnO3 prepared by tape casting

The structural and thermoelectric transport properties of Ca_0.9La_0.1–xCe_xMnO_3–δ (x = 0 – 0.1) prepared through tape casting process were investigated. The thermoelectric transport properties of CaMnO₃ were optimized by the La³⁺ and Ce³⁺ co-doping and tape casting process. The Ce³⁺ substitution substantially enhanced the dimensionless figure-of-merit (ZT) due to the increases in electrical conductivity and absolute Seebeck coefficient. Of the studied samples, Ca_0.9La_0.025Ce_0.075MnO_3–δ had the maximum ZT (0.17) at 800 °C, and this value was 42% and 70% larger than those of singly doped Ca_0.9La_0.1MnO_3–δ (0.12) and Ca_0.9Ce_0.1MnO_3–δ (0.10), respectively. We demonstrate that both the La³⁺ and Ce³⁺ co-doping and tape casting process are highly promising approaches in enhancing the high-temperature thermoelectric transport properties of CaMnO₃.     

Luminescence properties of Eu3+- and Tb3+-doped δ-Bi2O3 stabilized by Th4+ substitution

The extent of incorporating Eu³⁺ and Tb³⁺ for bismuth in the oxygen-deficient fluorite structured Bi_0.50Th_0.50O_y has been examined together with the comprehension of their luminescence characteristics. The samples were synthesized by solution combustion method from which doping limits of Eu³⁺ and Tb³⁺, respectively, in the fluorite structure was determined. Uniform distribution of constituent elements was confirmed from elemental mapping. Doping Eu³⁺ and Tb³⁺-ions introduced compressive strain and oxygen vacancies in the system. Raman spectra of doped samples confirmed the fluorite structure and revealed the existence of oxygen vacancies in them. While Tb-doped samples showed a systematic decrease in band gap with increase in dopant concentration, such systematic variation was not observed for Eu-doped samples. Conclusions about the local site symmetry around Eu³⁺ and Tb³⁺ ions in the defect fluorite structure have been drawn from the photoluminescent spectral analysis of doped samples. Energy transfer from Bi³⁺ to Eu³⁺ and Tb³⁺-has been observed in these samples. The Judd-Ofelt analysis has been carried out to understand luminescence characteristics in these samples.