CaMgP2O7∶Ce3+,Mn2+荧光粉的制备及其发光性能

采用高温固相法制备CaMgP2O7∶Ce3+,Mn2+荧光粉,并对其发光性质进行探究.荧光粉CaMgP2O7∶Ce3+,Mn2+在328 nm、351 nm与587 nm的发射峰分别归属于Ce3+的5d→2FJ跃迂和Mn2的4T1 (4G)→6A1(6S)跃迁.Ce3+的掺杂有效地提高了Mn2+的发光强度,同时电荷补偿剂Li+与Na+的添加也提高了CaMgP2O7∶Ce3+,Mn2+荧光粉的发光强度,依据Dexter能量传递公式判断CaMgP2O7基质中Ce3+对Mn2+的能量传递属于电四极-电四极相互作用引起的共振能量传递.     

单一基质Na2Ca3Si2O8∶Tb3+,Eu3+荧光粉发光性质和能量传递的研究

通过传统的高温固相法成功的制得了一系列紫外激发的硅酸盐荧光粉Na2 Ca3 Si2O8∶Tb3+,Eu3+.X射线衍射(XRD)研究表明所制得的荧光粉为纯相.在Na2Ca3Si2O8∶Tb3+,yEu3+荧光粉体系中,随着Eu3+的掺杂浓度增大,发射光谱中Tb3的特征峰发光强度降低而Eu3+的不断升高,并且荧光寿命不断减小,说明了Tb3+和Eu3之间能量传递方式是交换相互作用,能量传递效率(ET)达到了15.8;.此外,通过CIE色坐标观察到,随着Eu3+浓度的增加,样品从绿色变成黄色,最终变成红色.由于它多彩的颜色变化,所以它是一种用于制作多彩LED的良好材料.     

白光LED用绿色荧光粉Ba3(PO4)2∶Tb3+的发光性能研究

本文采用高温固相法制备出一种绿色荧光粉Ba3(PO4)2∶Tb3+,并通过X射线粉末衍射仪(XRD)和荧光分光光度计对所得荧光粉的结构和光谱性能进行了表征.结果 表明:Ba3(PO4)2体系中掺杂稀土离子Tb3+并没有引起结构的变化;荧光粉Ba3(PO4)2∶Tb3+的激发光谱的主峰位于485 nm,发射光谱的主峰位于548 nm、560 nm和647 rnm;荧光粉Ba3(PO4)2∶Tb3+中Tb3的最佳掺杂浓度为20mol;.由此可见,荧光粉Ba3(PO4)2∶Tb3是可被蓝光LED有效激发的绿色荧光粉.     

Ce3+敏化YAG∶Nd3+单晶的近红外发光性能研究

稀土离子的近红外发光性能在光通信和太阳能利用等领域应用广泛.针对材料近红外发光性能较弱的问题,采用Ce3的敏化作用,提高Nd3+的近红外发光性能.利用提拉法生长得到大尺寸的Ce3和Nd3+共掺杂Y3Al5O12(YAG)单晶,用X-射线衍射仪对其物相进行分析,并通过透射光谱对晶体透光率和吸收性质进行了表征.通过对Ce3+的激发和发射光谱分析,初步判断Ce3+和Nd3+间的能量传递行为.并通过Nd3+近红外激发和发射光谱分析,研究Ce3+对Nd3+发光的影响.实验结果表明,由于Ce3向Nd3+的有效能量传递作用,YAG∶Ce3+,Nd3+在450 nm蓝光激发时,近红外1 060 nm发光增强1.5倍.     

Tb3+,Yb3+共掺杂LuBO3荧光粉的下转换发光

利用水热法成功合成了近红外量子剪裁荧光粉LuBO3∶15;Tb3+,x; Yb3+(x=0,1,2,4,8,12).通过X射线衍射(XRD)、光致发光谱(PL)、激发谱(PLE)和荧光寿命测试了合成物质的物相结构与发光性质.在286 nm(Tb3+∶7 F6→5D)紫外光激发下,观察到了Tb3∶5D4→7Fj(J=6,5,4,3)可见波段特征发射光和Yb3+:2F5/2→2F7/2的近红外光.研究了Yb3+浓度与激发发射光谱和荧光寿命之间的关系,表明Tb3+和Yb3+之间存在能量传递.当Tb3和Yb3+掺杂摩尔浓度分别为15;和2;时,近红外发射最强.计算得知,其最大下转换量子效率为160.74;.     

Ca8Mg（SiO4）4Cl2∶Eu2+,Ce3+,Mn2+绿色荧光粉发光性能及其应用研究

利用高温固相法,合成出Eu2+、Ce3+、Mn2+共掺的Ca8Mg(SiO4)4Cl2系列绿色荧光粉。通过XRD表征了这些荧光粉的结构,通过分子荧光光谱仪研究了它们的室温发光性能。首先调查了Eu2+掺杂的Ca8Mg(SiO4)4Cl2绿色荧光粉发光性能,随后引入Ce3+、Mn2+提高了Ca8Mg(SiO4)4Cl2∶Eu2+在紫外光区的吸收强度及绿光发射强度。最后将筛选出来的荧光粉与InGaN-LED芯片组装制作成单一绿光LED器件,利用Ca7.8215MgSi4O16Cl2∶0.0525Eu2+,0.056Ce3+,0.070Mn2+所制作成的绿光LED器件发光最强,在20mA电流激发下,此LED发很强的绿光,其电致发光光谱所对应的色坐标值为:x=0.26,y=0.55。     

荧光粉SrCaSiO4∶Eu2+,Ce3+光谱性能及能量传递的研究

本文采用高温固相法合成了一种新型荧光粉SrCaSiO4∶Eu,Ce,并对其进行了光谱及荧光寿命衰减曲线的测试。结果表明:SrCaSiO4∶0.005Eu2+,0.01Ce3+可和紫外LED相匹配发射蓝绿光,且在该体系中存在着Ce3+到Eu2+的能量传递;在荧光粉SrCaSiO4∶Eu2+中共掺Ce3+将会使Eu2+的荧光寿命增长,同时发现此体系的Ce3+荧光寿命变短,这也证明了在此体系中存在着能量传递。     

近紫外光LED芯片用红色荧光粉SrIn2O4∶Eu3+,Sm3+的制备及性能研究

利用高温固相法制备了EH3+、Sm3单掺杂及共掺杂的SrIn2O4荧光材料.通过XRD、激发光谱、发射光谱等对SrIn2O4∶ Eu3+、SrIn2O4∶ Sm3+、SrIn2O4∶ Eu3+,Sm3+进行表征.结果表明,SrIn2O4∶ Eu3+在近紫外光395 nm激发下能够有效的产生616 nm的红光发射.在SrIn2 O4∶Sm3+体系中发现,该系列样品适合于407 nm的紫光激发,发射峰位于607 nm.在SrIn2O4∶Eu3+,Sm3+体系中,通过光谱分析发现,基质中存在Eu3和Sm3激活剂之间的相互能量传递过程.该能量传递过程使SrIn2O4∶Eu3+,Sm3+更适合于390～410 nm紫外芯片激发的LED用红色荧光粉.     

SiO2@Gd2O3∶Tb3+核壳微球的可控合成及发光性能研究

采用简便的尿素辅助沉淀法将Gd2O3∶Tb3+成功包覆在二氧化硅微球表面合成了尺寸均匀的球形SiO2@Gd2O3∶Tb3核壳发光材料,解决了稀土发光材料普遍存在的形貌可控性差和颗粒尺寸不均一等问题.利用XRD、SEM、红外光谱和荧光光谱等表征测试了样品的形貌、结构和发光性能.SEM照片和尺寸分布图显示,SiO2@Gd2O3∶Tb3+粒子呈现均匀球形形貌,分散性良好,粒径约(608 +18) nm.XRD图谱分析表明,600℃煅烧后,壳层Gd(OH)3CO3完全转变为立方相Gd2O3,结晶性良好,无杂相生成.同时,结合红外光谱推测了SiO2@Gd2O3∶Tb3核壳微球的形成机理,并得出Gd2O3∶Tb3+壳层主要以Si-O-Gd键形式连接在二氧化硅微球表面.在240 nm紫外光激发下,SiO2@Gd2O3∶Tb3核壳微球呈现绿光发射,其中,位于540 nm处的主峰归属于Tb3+的5D4→7F5能级跃迁.不同Tb3掺杂浓度下的发射光谱表明,当Tb3+掺杂浓度为4mol;时,SiO2@Gd2O3∶Tb3+核壳微球的发射强度达到最大值,寿命为1.55 ms,色坐标位于绿色区域,展现了良好的绿光发光性能.     

近紫外激发Ca2 NaMg2 V3 O12:Sm3+荧光粉的制备及发光性能

近紫外激发单一基质白光发射荧光粉是当前LED用荧光转换材料的研究热点.采用高温固相反应制备了Ca2 NaMg2 V3 O12:Sm3+荧光粉,并利用X射线粉末衍射仪和荧光光谱仪等测试手段,对其物质结构和荧光性能进行了表征.探讨了(VO4)3-基团的发光机理,及其与Sm3+离子之间的能量传递机制.结果表明:Ca2 NaMg2 V3 O12:Sm3+荧光粉属于立方相晶体结构.在340 nm紫外线激发下,样品发射蓝绿光,发射最强峰位于500 nm,发射光谱覆盖整个可见光区.Sm3+离子的最佳掺杂浓度为0.03,同时(VO4)3-基团与Sm3+离子之间的能量传递主要是通过电四偶极-电四偶极相互作用来实现的.     

Visible up-conversion photoluminescence from IR diode-pumped SiO2–TiO2 nano-composite films heavily doped with Er3+–Yb3+ and Nd3+–Yb3+

Efficient infrared-to-visible conversion is reported in thin film nano-composites, with composition 90% SiO₂–10% TiO₂, fabricated by a spin-coating sol–gel route and co-doped with Er³⁺ Yb³⁺ and with Nd³⁺:Yb³⁺ ions. The conversion process is observed under 808 nm laser diode excitation and results in the generation of green (526 and 550 nm) and red (650 nm) emissions: from the former, and blue (478 nm) and green (513 and 580 nm) emissions from the latter. The main mechanism that allows for up-conversion is ascribed to energy transfer among Er³⁺ and Yb³⁺ ions in their excited states. Up-conversion efficiency for red emission predominates in samples doped with Er³⁺:Yb³. The results illustrate the large potential of this class of materials for photonic applications in optoelectronics devices.     

Spectroscopic properties and energy transfer in Ga2O3– Bi2O3–PbO–GeO2 glasses codoped with Tm3+ and Ho3+

This paper reports on the spectroscopic properties and energy transfer in Ga₂O₃–Bi₂O₃–PbO–GeO₂ glasses doped with Tm³⁺ and/or Ho³⁺. From the optical absorption spectra of Tm³⁺, Judd–Ofelt intensity parameters, radiative transitions probabilities, fluorescence branching ratios, and radiative lifetimes have been calculated using Judd–Ofelt theory. The measured differential scanning calorimetry result shows that the glass exhibits excellent stability against devitrification with ΔT = 129 °C. The measured luminescence spectra show that the ³H₄ → ³F₄ transition of Tm³⁺ upon 808 nm laser diode excitation possess a broad full width at half-maximum of ∼126 nm. The maximum value calculated stimulated emission cross-section and the measured lifetime of ³H₄ level from the 1.47-μm transition are ∼4.73 × 10⁻²¹ cm² and ∼0.239 ms, respectively. It is noticed that codoping of Ho³⁺ could significantly enhanced the ratio of the intensity of 1.47–1.80 μm by energy transfer via Tm³⁺: ³F₄ → Ho³⁺: ⁵I₇.     

溶胶-凝胶法制备Zn3Ga2Ge2O10:Cr3+0.01,Pr3+0.03,Yb3+0.3纳米长余辉材料及其表面修饰的研究

以Ga(NO3)3·8H2O、Zn(NO3)2·6H2O、Pr(NO3)2·6H2O、GeO2、Yb(NO3)3·5H2O、Cr(NO3)2·9H2O为原料,采用溶胶-凝胶法合成了Cr3+,Pr3+,Yb3+共掺杂的Zn3Ga2Ge2O10长余辉纳米材料(PLNPs).利用XRD,SEM,激发发射图谱,余辉曲线测试确定1000℃煅烧,保温3 h时,基质Zn3 Ga2 Ge2 O10已形成.Yb3+掺杂百分比为0.3时,样品的发光性能最好.Zn3 Ga2 Ge2 O10:Cr3+0.01,Pr3+0.03,Yb3+0.3纳米长余辉材料在波长为267 nm的紫外线激发下发射出中心波长为745 nm的深樱桃红色光,此时晶粒粒径约为150 nm;随着Yb3+掺杂百分比的增加,晶粒粒径逐渐变小.通过FT-IR,Zeta电势,激光粒度测试,TEM及悬浮实验测试表明,PEG修饰PLNPs后,可观察到明显的核壳结构,水合粒径约为155 nm;水溶性大大增加,0.3 mg/mL的浓度下其悬浮时间超过48 h,这表明PEG包裹PLNPs成功.     

Eu3+掺杂Sr3Y2TeO9的红色荧光粉

采用高温固相法制备了一系列Sr₃Y_2-xTeO₉∶xEu³⁺新型红色荧光粉,研究了Sr₃Y_2-xTeO₉∶xEu³⁺的物相结构、发光性能、衰减寿命以及热稳定性。研究结果表明新型红色荧光粉Sr₃Y_2-xTeO₉∶xEu³⁺能在近紫外光或蓝光激发下发出强烈的红光,并确定了Sr₃Y_2-xTeO₉∶xEu³⁺的浓度猝灭机制是电偶极-电偶极之间相互作用。其色坐标结果表明,随着掺杂浓度的增加该荧光粉的色坐标均在红色区域。温度相关荧光发射光谱揭示了该荧光粉具有良好的热稳定性。荧光衰减曲线显示在Sr₃Y_2-xTeO₉∶xEu³⁺荧光粉中当x=0.34时为最佳掺杂浓度,其平均荧光寿命为0.619 ms。综合以上研究结果表明新型红色荧光粉Sr₃Y_2-xTeO₉∶xEu³⁺在荧光转换近紫外激发白光二极管中具有良好的应用前景。     

Li2 CO3-Y3+共掺杂TiO2纳米材料的制备及光催化性能的研究

采用溶胶-凝胶法制备了Y3+-TiO2纳米粒子,利用X-射线衍射仪(XRD)、扫描电镜(SEM)、紫外-可见光谱(UV-vis)等仪器对样品的物化性质进行了表征.以对亚甲基蓝为目标降解物,考查了Y3+掺杂对纳米TiO2光催化活性的影响.实验结果表明,掺杂浓度摩尔比为0.03的Y3+有利于提升TiO2光催化活性,能有效提高对亚甲基蓝的光催化降解效率.对TiO2纳米粒子进行了Y3+和Li2 CO3共掺杂,Li2 CO3共掺Y3+-TiO2相比于Y3+-TiO2对亚甲基蓝的光催化降解效率有了进一步的提升,同时对相关机理进行了详细的论证,推测Li2 CO3在本研究中起到空穴补偿剂而不是电荷补偿剂的作用.     

Time-resolved fluorescence measurements on Eu3+- and Eu2+-doped glasses

Various fluoride, phosphate and borosilicate glasses with known properties and global structure have been doped with Eu³⁺ (4f⁶) at doping concentrations between 10¹⁸ and 10²¹ cm^?3. By applying reductive melting conditions Eu³⁺ could partially be transformed to Eu²⁺ (4f⁷). Four fluoroaluminate glasses with varying phosphate content between 0 and 20 mol% (FPx), a pure phosphate glass (P100) and two borosilicate glasses with low (DURAN^®-like) and high optical basicity (NBS1) have been used for these investigations. The time-resolved fluorescence in the visible range has been studied for both ions. Although static and dynamic fluorescence of Eu³⁺ and Eu²⁺ are dramatically different (f–f-transitions for Eu³⁺; d–f-transitions for Eu²⁺), glass structure changes have a similar influence on the dynamic fluorescence behavior of both ions. A strongly ionic surrounding due to fluorine ligands as in fluoroaluminate glass samples provides the longest fluorescence lifetime (about 7 ms for Eu³⁺; about 1.3 μs for Eu²⁺). Increasing phosphate content decreases the fluorescence lifetime due to more oxygen ligands. Interesting differences have been found for the two borosilicate glasses due to the difference in their optical basicity (Na₂O/B₂O₃ ratio). Measurements indicate a homogeneous distribution of europium ions in most FP samples. NBS1 measurements suggest that two different local europium sites are formed. For Duran-like samples only one specific europium site was found, although these samples show phase separation at high doping concentrations into a SiO₂-rich phase and borate- and europium-rich droplets. Fluorescence quenching due to energy transfer from Eu²⁺ to Eu³⁺ could be found for co-doped samples; Eu³⁺-doped samples show no fluorescence quenching.     

Preparation of crystalline fibres of codoped BaAl2O4:Eu2+:Cr3+

Phosphor material BaAl₂O₄:Eu²⁺, Cr³⁺ with varying concentrations of Cr co‐doping were prepared by solid‐state synthesis method. Crystalline fibres were obtained by controlled annealing temperature. Synthesized compositions were characterized for their phase and crystallinity by powder x‐ray diffraction. The crystalline morphology was investigated using SEM analysis. High resolution transmission electron microscopy (HRTEM) in image and diffraction modes was used to investigate the microstructure. The effect of Cr doping on quality and morphology of grown crystals was investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetic resonance study of the crystallization behavior of InF3-based glasses doped with Cu2+, Mn2+ and Gd3+

The crystallization of fluoroindate glasses doped with Gd³⁺, Mn²⁺ and Cu²⁺ heat treated at different temperatures, ranging from the glass transition temperature (T_g) to the crystallization temperature (T_c), are investigated by electron paramagnetic resonance (EPR) and ¹⁹F nuclear magnetic resonance (NMR). The EPR spectra indicate that the Cu²⁺ ions in the glass are located in axially distorted octahedral sites. In the crystallized glass, the g-values agreed with those reported for Ba₂ZnF₆, which correspond to Cu²⁺ in a tetragonal compressed F⁻ octahedron and to Cu²⁺ on interstitial sites with a square-planar F⁻ co-ordination. The EPR spectra of the Mn²⁺ doped glasses exhibit a sextet structure due to the Mn²⁺ hyperfine interaction. These spectra suggest a highly ordered environment for the Mn²⁺ ions (close to octahedral symmetry) in the glass. The EPR spectra of the recrystallized sample exhibit resonances at the same position, suggesting that the Mn²⁺ ions are located in sites of highly symmetric crystalline field. The increase of the line intensity of the sextet and the decrease of the background line in the thermal treated samples suggest that the Mn²⁺ ions move to the highly ordered sites which contribute to the sextet structure. The EPR spectra of the Gd³⁺ doped glasses exhibit the typical U-spectrum of a s-state ion in a low symmetry site in disordered systems. The EPR of the crystallized glasses, in contrast, have shown a strong resonance in g ≈ 2.0, suggesting Gd³⁺ ions in environment close to cubic symmetry. The ¹⁹F NMR spin–lattice relaxation rates were also strongly influenced by the crystallization process that takes over in samples annealed above T_c. For the glass samples (doped or undoped) the ¹⁹F magnetization recoveries were found to be adjusted by an exponential function and the spin–lattice relaxation was characterized by a single relaxation time. In contrast, for the samples treated above T_c, the ¹⁹F magnetization-recovery becomes non-exponential. A remarkable feature of our results is that the changes in the Cu²⁺, Mn²⁺, Gd³⁺ EPR spectra and NMR relaxation, are always observed for the samples annealed above T_c.     

Luminescence properties of Sm3+-doped polycrystalline ZrO2

We obtained samarium-doped zirconia using two different routes. In one, atomic layer deposited thin crystalline films were doped by using ion implantation; this sample was mainly monoclinic. The other method, the skull-melting technique, yielded polycrystalline bulk zirconia containing both monoclinic and tetragonal phases of ZrO₂. Thorough photoluminescence (PL) measurements of Sm emission in these materials were performed using pulsed laser excitation at 405, 320 and 230 nm, respectively corresponding to direct, defect-related and host-sensitized excitation. Both samples exhibited well-resolved emission series of Sm³⁺. In general, the recorded spectra may be considered as superpositions of two different sets of lines attributable to Sm³⁺ centers in different crystalline phases of ZrO₂. These results have been confirmed by time-resolved measurements, which also suggest that all emission lines originate from a common initial state (⁴G_5/2) with a lifetime of about 1 ms. As expected, the host-mediated excitation leads to a prolonged decay profile attributed to the retarded energy transfer from host to guest.     

Sr3Ga2Ge4O14∶Eu3+,Bi3+粉体的光谱特性及能量传递研究

研究了Eu3和Bi3+共掺锗酸镓锶粉体的合成、结构及其光谱性能.结果表明,合成粉体为纯三方相结构,掺杂没有引起新相生成,表明部分无序结构为掺杂离子提供更大的包容空间,从而实现激活离子的高浓度掺杂.高温固相合成的粉体在蓝绿光区域(570～700 nm)具有丰富的发射峰,其主峰位于618 nm,是Eu3处于非对称中心格位产生的特征峰,由此说明Eu3+取代Sr2+的位置;当Eu3+的掺杂浓度为15mol;时,在618 nm处发光强度达到最大.掺Bi3+明显增强了Eu3+的发光,是一种有效的敏化剂;当Bi3+掺杂量为5mol;时,Eu3+的相对发光强度同比提高了51.3;.