NIR to visible upconversion in Er/Yb co-doped CaYAl3O7 phosphor obtained by solution combustion process

Using the combustion synthesis, CaYAl₃O₇:Er³⁺ phosphor powders co-doped with Yb³⁺ have been prepared at low temperatures (550 °C) in a few minutes. Formation of the compound was confirmed by X-ray powder diffraction. Near-infrared to visible upconversion fluorescence emission in the Er³⁺ doped CaYAl₃O₇ phosphor powder has been observed. The effect of co-doping with triply ionized ytterbium in the CaYAl₃O₇:Er³⁺ phosphor has been studied and the process involved is discussed.     

La1．6（MoO4）3∶Eu3＋0．4纳米晶合成及发光特性

采用燃烧法合成了La1．6（MoO4）3∶Eu3＋0．4纳米晶末,研究了其声子-掺杂-晶格相互作用和发光性质。 X射线粉末衍射（XRD）分析表明,在500～900℃退火后,La1．6（MoO4）3∶Eu3＋0．4样品为单一晶相。对样品进行了光致发光（PL）测量,激发Mo6＋-O2－电荷迁移带,观察到Eu3＋的系列发光,表明Mo6＋-O2－带和Eu3＋间存在能量传递,中心波长分别在λ1＝469 nm和λ2＝426 nm处的两个one-phonon边带,相应的声子能量分别为767和1202 cm－1,分别对应于Mo O和Mo—O—Mo伸缩振动。同时,计算了两个局域模电子-声子耦合强度的黄昆因子分别为S1＝0.055和S2＝0.037,为揭示其三价离子高传导特性及其负热膨胀物理特性提供了实验基础。     

Luminescence and scintillation of Eu2+‐doped high silica glass

High silica glass doped with Eu²⁺ ions was prepared as a scintillating material by impregnation of Eu ions into a porous silica glass followed by reduction sintering in CO atmosphere. A dominant emission band of the Eu²⁺ 5d–4f transition peaking around 430 nm was observed in the luminescence spectrum with the excitation peak around 280 nm and no emission from Eu³⁺ was present. Photoluminescence decay kinetics was governed by decay times of a few microseconds. The Eu²⁺‐doped high silica glass exhibited comparable energy resolution and slightly higher photoelectron yield with respect to the Bi₄Ge₃O₁₂ crystal in the pulse height spectra for X‐ray photon energies within 22–60 keV. Furthermore, a factor of 1.2 higher radioluminescence intensity was observed as well. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of precipitant solution pH on the structural, morphological and upconversion luminescent properties of Lu2O3:2%Yb, 0.2%Tm nanopowders

Lutetium oxide nanopowders codoped with Tm³⁺ and Yb³⁺ were synthesized by the reverse-strike co-precipitation method. Effects of precipitant solution pH on the structural, morphological and upconversion luminescent properties of Lu₂O₃:2%Yb, 0.2%Tm nanopowders had been investigated. The results show that pH value of the precipitant (NH₄HCO₃) solution has a significant effect on the particle size, morphology and upconversion emission intensity of the Lu₂O₃:2%Yb, 0.2%Tm nanopowders. All the samples obtained from different pH value of precipitant solution can be readily indexed to pure cubic phase of Lu₂O₃, indicating good crystallinity. The upconversion emission intensity of Lu₂O₃:2%Yb, 0.2%Tm nanopowders obtained from the precipitant solution with pH=11 is the strongest. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing the number of OH⁻ groups and the enlarged nanopowder size. The strong blue, weak red and near infrared emissions from the prepared nanopowders were observed under 980 nm laser excitation, and attributed to the ¹G₄→³H₆, ¹G₄→³F₄ and ³H₄→³H₆ transitions of Tm³⁺ ion, respectively.     

一维光子晶体微腔在硅基材料发光中的应用研究

硅基材料的高效发光对未来硅基光电子集成的发展极其关键,含微腔的一维光子晶体可以显著提高其发光强度、窄化其发光峰.介绍了几种硅基材料发光的一维光子晶体微腔结构,包括单缺陷模式的对称与非对称结构、多缺陷模结构及电注入结构.利用传输矩阵法计算其缺陷模透射谱,以间接分析其发光谱.     

Spectral and kinetic characteristics of CdI<Subscript>2</Subscript> and CdI<Subscript>2</Subscript>:Pb scintillators

We have studied the effect of lead dopant on the optical absorption, photoluminescence, and x-ray luminescence spectra, and the scintillation characteristics of CdI₂ at room temperature. The crystals for the study were grown by the Stockbarger-Bridgman method. Activation of CdI₂ from the melt by the compound PbI₂ leads to the appearance in the absorption spectra in the near-edge region of an activator band at 395–405 nm, which is interpreted as an A band connected with electronic transitions from the ¹S₀ state to the ³P₁ levels in the Pb²⁺ ion. For x-ray excitation, CdI₂:Pb²⁺ crystals with optimal dopant concentration (∼1.0 mol%) are characterized by a light yield with maximum in the 570–580 nm region that is an order of magnitude higher than for CdI₂ crystals in the 490–500 nm band. For α excitation, the radioluminescence kinetics for cadmium iodide is characterized by a very short (∼0.3 nsec) rise time and fast decay of luminescence, with τ₁ ≈ 4 nsec and τ₂ = 10–76 nsec. Depending on the conditions under which the crystals were obtained, the fast component fraction is 95%–99%. The crystal is characterized by a similar scintillation pulse in the case of excitation by x-ray pulses. The radioluminescence pulse shape for CdI₂:Pb in the decay stage is predominantly exponential, with luminescence decay time constants τ₁ ≈ 10 nsec and τ₂ = 200–250 nsec. This system is characterized by low afterglow, at the level for the Bi₄G₃O₁₂ scintillator. We have demonstrated the feasibility of using CdI₂:Pb as a scintillator for detecting α particles. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 825–830, November–December, 2008.     

显示用上转换绿色发光材料NaYF4∶Er,Yb及其特性

采用喷射微波燃烧合成法制备了上转换发光显示器中发绿光的上转换发光材料NaYF4∶Er,Yb.测试了该材料的XRD衍射图谱和发光效率.给出了该材料在1 064 nm三种激光功率激发下的发光光谱.分析了该材料的上转换发光机理,得到545 nm和662 nm峰值发光分别是Er3+的4S3/2→4I15/2和4F9/2→4I15/2跃迁产生的.NaYF4∶Er,Yb具有较强的上转换绿光,同时存在的较弱的红光易于用滤色膜滤除,满足显示对三基色中绿色的要求;并且喷射微波燃烧合成法制备的该材料达到了高分辨率显示应用超细粉体的要求.     

K+和Al3+掺杂对掺Er3+溶胶凝胶玻璃发光特性的影响

通过Sol-gel(溶胶-凝胶)技术,首次将Al3 离子和K 离子同时引入到掺Er3 硅酸盐玻璃中,并测定了硅基玻璃中Er3 离子的吸收光谱、透射光谱、光致发光光谱(PL谱)、上转换光谱、拉曼光谱及荧光寿命.结果显示:掺入的Al3 离子和K 离子不但分别使Er3 离子的荧光强度增强20倍和70倍,而且使Er3 离子在1 532 nm处的荧光寿命从4.8 ms延长至7.1和11.2 ms,但经过进一步分析可知两者对其的影响机制却完全不同;同时作者发现,在980 nm波长激发下,Er3 离子的上转换荧光应该同时存在两种发光机制:双光子吸收和能量传递上转换.     

退火温度对ZrO2纳米材料中Eu3+离子发光的影响

研究了退火温度对ZrO₂纳米材料中Eu³⁺离子发光性质的影响. 材料的结构、晶粒尺寸和形状以及晶格的排列分别由XRD，TEM表征. 结果表明：用共沉淀法制备的ZrO₂纳米材料具有不随退火温度变化、稳定的四方结构；材料的晶粒尺寸随退火温度的提高而增大；晶格的排列由无序逐渐变为有序；发射光谱表明其主要发射在595 nm和604 nm处；在394 nm的紫外光辐照下得到了不同样品的604 nm荧光发射强度的变化不同. 这种现象与样品中O^2-离子含量和样品表面的表面缺陷有关；另外，电荷迁移带随退火温度的变化而变化.     

Cd3Al2Ge3O12:Mn2+锗酸盐石榴石光谱性质

本文报道室温下Cd₃Al₂Ge₃O₁₂:Mn²⁺(简称CAGG:Mn²⁺)锗酸盐石榴石的漫反射光谱、激发和发射光谱.在UV光激发下,在CAGG中Mn²⁺离子发射强黄光,这是基质到Mn²⁺离子无辐射能量传递的结果.Mn²⁺的黄发射带是由一个弱的红带和一个强的绿带所组成.讨论了这两个Mn²⁺发射带的起因.