球形La2O3∶Eu纳米晶的制备及其发光特性

The spheric La₂O₃∶Eu nanocrystals were prepared using NH₃·H₂O-NH₄HCO₃ mixture as precipitant. The material was characterized by FTIR, XRD and TEM techniques. The luminescence properties of Eu³⁺ in spheric La₂O₃ were measured by three dimension spectra, emission and excitation spectra. The results indicate that the La₂O₃∶Eu nanocrystals are in hexagonal phase by annealing at 800 ℃, the crystal size is about 30 nm. The maximum emission and excitation wavelength were determined by three dimensional spectroscopy to be at 591 nm and 394 nm, respectively. In emission spectrum the band at 591 nm and 612 nm are corresponding to ⁵D₀-⁷F₁ and ⁵D₀-⁷F₂ transition of Eu³⁺ ions. With increasing in annealing temperature the differences of intensity of the two transitions are increased. This phenomenon shows that the luminescence intensity of La₂O₃∶Eu nanocrystals can be tuned by changing annealing temperature.     

稀土红色荧光粉SrZnO2∶Eu3+的发光性能

A series of novel luminescent materials, SrZnO₂∶M (M=Eu³⁺, or Eu³⁺ + Li⁺) have been synthesized by high-temperature solid-state reaction. The structure and luminescence properties of SrZnO₂∶Eu³⁺ phosphor were studied through XRD, photoluminescence and Raman spectroscopy. The excitation spectra show a broad intense band and a number of small peaks corresponding to the inner 4f-shell excitations of Eu³⁺ (the strongest one is at 395 nm for ⁷F₀-⁵L₆). After SrZnO₂∶Eu³⁺ phosphor was co-doped with Li⁺ ions, its charge transfer band extended to longer wavelengths. This resulted in increase of luminescent quantum efficiency of the sample. SrZnO₂∶Eu³⁺,Li⁺ phosphor can be efficiently excited by longer UV. From the fluorescence spectrum of SrZnO₂∶Eu³⁺ phosphor, apart from transition emissions of ⁵D₀→ ⁷F_J (J=0～4), the transition emissions from ⁵D₁ → ⁷F_J (J=0～2) have been observed. For the SrZnO₂∶Eu³⁺ phosphor, under excitation of UV, the dominant emission is at about 612 nm, due to the ⁵D₀→ ⁷F₂ hypersensitive transition. The incorporation of Li⁺ ions greatly enhanced the luminescence intensity and made emission peak from ⁵D₀ → ⁷F₂ transition red-shifted.     

助熔剂法制备的LaMgAl11O19∶Eun+(n=2，3)的发光特性

LaMgAl₁₁O₁₉∶Euⁿ⁺(n=2,3) was synthesized by solid state reaction using H₃BO₃ as a flux at 1 400 ℃ for 4 hours. And their luminescent properties was investigated under UV and VUV excitation. Strong pure blue emission due to d-f transition of Eu²⁺ was observed in LaMgAl₁₁O₁₉∶Eu²⁺ both in 254 nm and 147 nm excitation. At the same time, red emission due to ⁵D₀ → ⁷F_J (J=0, 1, 2, 3, 4) transition of Eu³⁺ also observed in LaMgAl₁₁O₁₉∶Eu³⁺. The dependence of emission intensity of blue/red emission on Eu²⁺ / Eu³⁺-content was evaluated. The result indicated that the blue emission intensity was arrived optimum when Eu²⁺-content was 0.10 mol·mol^-1under both UV and VUV excitation while red emission intensity reached optimum when Eu³⁺-content was 0.125 mol·mol^-1 under UV excitation. This suggests that LaMgAl₁₁O₁₉∶Eu²⁺ phosphors could be potential blue phosphor for the application in PDP.     

Eu3+在Ba2TiSi2O8中的发光

The barium titano-silicate phosphors doped with Eu³⁺ were synthesized by high temperature solid state reaction. The structures of as-synthesized samples were characterized by powder XRD. The maximum peaks of emission spectra of Ba₂TiSi₂O₈ and Ba₂TiSi₂O₈∶Eu³⁺ were respectively located at 450 and 618 nm, coming from the transitions of charge-transfer bands of Ti⁴⁺-O^2- and forced electric-dipole transition ⁵D₀-⁷F₂ of Eu³⁺. The luminous mechanisms of Ba₂TiSi₂O₈ and Ba₂TiSi₂O₈∶Eu³⁺ were suggested. The effects of concentration of Eu³⁺ on the luminous performance of Ba₂TiSi₂O₈∶Eu³⁺ were also studied and the results showed that the optimum concentration of Eu³⁺ was 0.12 mol per mole of matrix.     

水热法制备具有光滑表面的球形Y2O3∶Eu3+发光材料

The spherical Y₂O₃∶Eu³⁺ luminescent particles with size of 0.5～3 μm and smooth surface were synthesized by hydrothermal method. The resulted Y₂O₃∶Eu³⁺ precursors and the calcined particles were characterized by differential thermal analysis (DTA) and thermogravimetric (TG) analysis, X-ray diffraction (XRD), Fourier-transform IR spectroscopy (FTIR), scanning electron microscopy (SEM) and photoluminescence spectra (PL). FTIR, TG-DTA, XRD measurements show that the precursors are crystal with hydroxyl and carbonate group, and the pure cubic yttria is obtained after annealing above 700 ℃. The SEM images indicate that the Y₂O₃∶Eu³⁺ particles are in spherical shape and with smooth surface. PL analysis shows that the particles present characteristic red emission of Eu³⁺.     

Eu3+离子在Ca2PbO4一维结构基质中的发光研究

A Eu³⁺-doped Ca₂PbO₄ with one-dimensional structure was prepared with a solid-state reaction method and its characteristics were investigated. The XRD results show that the substitution of Ca²⁺ by Eu³⁺ has no influence on the structure of Ca₂PbO₄. Under the excitation of ultraviolet light， the Ca₂PbO₄:Eu³⁺ phosphor exhibits strong red emission at about 618 nm which is assigned to the ⁵D₀- ⁷F₂ electric-dipole transition. The compounds Sr₂CeO₄ and Ca₂SnO₄ have the same crystal symmetry as that of Ca₂PbO₄ and it is found that the emission intensity of Ca₂PbO₄∶Eu³⁺ is higher than that of Sr₂CeO₄∶Eu³⁺ and lower than that of Ca₂SnO₄∶Eu³⁺. The excitation spectrum of Ca₂PbO₄∶Eu³⁺ appears to be a broad band with two peaks at about 289 nm and 340 nm. The former peak is attributed to the Eu³⁺-O₂- charge transfer transition， while the latter one may be related to the absorption of Ca₂PbO₄ host or its crystal defects.     

一维Y2O3∶Eu3+纳米发光材料的制备与表征

One-dimensional Y₂O₃∶Eu³⁺ luminescence nanomaterials were prepared by hydrothermal method without template, and their properties were characterized. XRD patterns show that the precursors are hexagonal phase Y(OH)₃ crystals, and the samples are cubic Y₂O₃ after heat-treatment. SEM images indicate that the one-dimensional material with a diameter of 100 nm and length of micrometer scale can be obtained by this hydrothermal method. Photoluminescence properties show that the position and intensity of the precursors are different with that of the heat-treated samples resulted from the different hosts.     

发光材料BaAl2Si2O8∶Eu2+的物相结构与发光性能

A phosphor, Ba_0.97Al₂Si₂O₈∶Eu²⁺, was synthesized by high temperature solid-phase method at different temperatures. The samples were characterized by TG/DTA, XRD and fluorescence spectroscopy. The results show that the main phase for host of these luminescence materials is barium feldspar BaAl₂Si₂O₈∶Eu²⁺ and there is a transition from hexagonal crystal system to monoclinic crystal system in the process of the sintering of barium feldspar. The luminescent phenomen of barium feldspar with hexagonal structure can not be observed under the excitation of ultraviolet lamp of 365 nm while the barium feldspar with monoclinic structure has excellent luminescence properties. The excitation spectra of all these samples show broad band spectra ranging from 250～390 nm with peak at λ_ex of 357 nm,which indicates that these samples can be effectively excited by near ultraviolet ; the emission spectra range from 380～600 nm with peak at λ_em of 433 nm. The luminescent intensity increases then decreases with the concentration of doping Eu²⁺ ions. When the concentration of dopants is 2.5mol%, the luminescent intensity reaches the maximum value. When the concentration of Eu²⁺ ions changes from 0.5mol% to 2.5mol%, the emission peak has a red shift from 427 nm to 440 nm.     

Si5P6O25∶Tb3+的结构与荧光性质

Tb³⁺ ions were incorporated in P-Si matrix material through a sol-gel process. Luminescence properties of Tb³⁺ as a function of dopant， firing temperature， composition and structure of matrices were investigated. The gels synthesized by the reaction of P₂O₅ or H₃PO₄ with tetraethoxy silane and TbCl₃ as dopant were fired in air from the temperature 25～1000℃ to form P-Si crystalline phase. The crystal structure was determined by powder X-ray diffraction. Si₅O(PO₄)₆ were the only crystalline phase and belong to hexagonal crystal system. The emission of ⁵D₄-⁷F₅(～545nm) transition of Tb³⁺ in the P-Si system is composed of two peaks. The amount of doping Tb³⁺ varied from 0.664% to 1.644%， and no obvious concentration quenching was observed in this doping concentra-tion range. The intensity of Tb³⁺ emission increased with firing temperature increasing and becomes stable at 800～1000℃.     

Sr3SiO5∶Eu2+荧光粉的微波合成及性能研究

Silicate orange yellow phosphor used in white-light LED was prepared by microwave method. The structure and optical properties of phosphor were studied. Sr₃SiO₅∶Eu²⁺ phosphor synthesized by microwave method is tetragonal structure of Sr₃SiO₅ with uniform particle distribution. Luminescence spectrum is a broad band spectrum peaking at 575 nm. The peak of excitation is at 532 nm and phosphor can be excited by blue LED. The warm white light was obtained combined phosphor and blue LED. The CIE chromaticity coordinates and correlated color temperature of white light is (x=0.394, y=0.341) and 3 239 K respectively.     

氨基酸-BrO-3-Mn2+-H2SO4-丙酮体系的振荡反应

This paper, Using potentiometric method, first reports the oscillating behavior of five amino acids (L-methionine, L-cystine, L-tryptophan, L-serine, L-tyrosine) in a new oscillating system of amino acid-BrO_3~--Mn~(2+)-H_2SO_4-acetone. The effect of many factors on oscillation have been investigated. According to Arrhenius equation, the apparent activation energy of the oscillatary induction period and oscillation period of five oscillating systems are obtained within temperature range of 20～37 ℃.     

Ho3+/Yb3+共掺ZnO-Al2O3-GeO2-SiO2玻璃陶瓷的制备和上转换发光性质

综合ZnO-Al₂O₃-SiO₂系和锗酸盐玻璃陶瓷的优点,采用熔融-晶化法首次制备了Ho³⁺/Yb³⁺共掺以ZnAl₂O₄为主晶相的ZnO-Al₂O₃-GeO₂-SiO₂系玻璃陶瓷。因[GeO₄]四面体和[SiO₄]四面体都是玻璃网络形成体,讨论了GeO₂取代SiO₂对玻璃陶瓷样品硬度及发光性能的影响,最终确定GeO₂的取代量为10.55%（w/w）时,玻璃陶瓷综合性能最佳。在980 nm泵浦光的激发下,发现强的绿色（546 nm）和弱的红色（650 nm）上转换发光,并研究了不同Ho³⁺/Yb³⁺掺杂比对样品上转换发光的影响,最终结果表明当Ho³⁺/Yb³⁺掺杂比为1：11（n/n）时样品荧光强度最强,在绿色上转换发光材料方面具有潜在的应用。     

PO43-掺杂Bi2O2CO3/Bi0的制备及其可见光催化性能

构建氧空位以及附着金属单质Bi(Bi⁰)是增强半导体材料光吸收性能、促进半导体光生载流子分离的有效方法。通过简单的共沉淀法及氢气热还原成功制备了PO₄^3-掺杂Bi₂O₂CO₃附着Bi⁰(Bi-P-BOC)的可见光催化剂,并对其在可见光下催化降解氧氟沙星(OFX)的性能及机理进行了研究。材料表征结果表明BOC随着PO₄^3-的均匀掺杂,可见光吸收能力增强,表面缺陷增多,比表面积增大。而随着氢气热还原,BOC表面形成 Bi⁰的同时也原位构建了大量的氧空位。可见光催化性能测试表明,Bi-P-BOC可以在180 min内降解约85%的OFX,降解速率为0.013 0 min^-1,是BOC降解速率的8倍。Bi-P-BOC光催化降解机理表明其具有更好的可见光吸收能力,Bi⁰以及氧空位的存在促进了光生载流子的分离,h+是其光催化降解过程中的主要的活性氧物种(ROS),此外,¹O₂和·O₂^-也对降解有一定贡献。     

Ce3+,Tb3+,Eu3+共掺杂Sr2MgSi2O7体系的白色发光和能量传递机理

通过正交试验,采用高温固相法制备了Sr2-x-y-zMgSi2O7∶xCe3+,yTb3+,zEu3+系列样品.使用X射线衍射仪和荧光光谱仪表征了样品的物相和发光性质,并讨论了Ce3+-Tb3+-Eu3+共掺杂Sr2MgSi2O7体系中的能量传递过程.实验结果表明,在327 nm波长激发下,所合成荧光粉的发射峰主要位于387 nm(蓝紫)、542nm(绿)和611 nm(红)处;分别以387,542和611 nm为监控波长,所得激发光谱显示荧光粉在327 nm处有最好的激发.在327 nm光激发下,系列样品发光进入白光区.最优化的荧光粉为Sr1.91MgSi2O7∶0.01Ce3+,0.05Tb3+,0.03Eu3+,其色坐标为(0.337,0.313),是一种潜在的发光二极管(LED)用白色荧光粉.     

PO43-掺杂Bi2O2CO3/Bi0的制备及其可见光催化性能

构建氧空位以及附着金属单质Bi(Bi⁰)是增强半导体材料光吸收性能、促进半导体光生载流子分离的有效方法。通过简单的共沉淀法及氢气热还原成功制备了PO₄^3-掺杂Bi₂O₂CO₃附着Bi⁰(Bi-P-BOC)的可见光催化剂,并对其在可见光下催化降解氧氟沙星(OFX)的性能及机理进行了研究。材料表征结果表明BOC随着PO₄^3-的均匀掺杂,可见光吸收能力增强,表面缺陷增多,比表面积增大。而随着氢气热还原,BOC表面形成Bi⁰的同时也原位构建了大量的氧空位。可见光催化性能测试表明,Bi-P-BOC可以在180 min内降解约85%的OFX,降解速率为0.013 0 min^-1,是BOC降解速率的8倍。Bi-P-BOC光催化降解机理表明其具有更好的可见光吸收能力,Bi⁰以及氧空位的存在促进了光生载流子的分离,h⁺是其...     

Cu/SO42-/La2O3-ZrO2-Al2O3催化剂的制备及其对C3H6选择还原NO的催化性能

以Al₂O₃为基质，添加ZrO₂和La₂O₃，制成La₂O₃-ZrO₂-Al₂O₃复合载体，然后采用SO₄^2-进行改性，再负载上Cu²⁺，制备了铜基SO₄^2-改性的复合载体催化剂(Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃)。考察了它在富氧条件下对丙烯选择还原NO的催化性能，并借助XRD、SEM、TG、Py-IR、NH₃-TPD、FTIR和TPR等方法研究了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃的结构和性能的关系。结果表明，ZrO₂的加入主要有利于提高催化剂的低温活性；La₂O₃的加入则主要有利于提高催化剂的热稳定性和还原性能；SO₄^2-能够与Zr形成螯合双配位结构，大幅度促使催化剂表面酸量增加并且酸性增强；因此，有效地提高了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃在富氧条件下对丙烯选择还原NO的催化活性和水热稳定性。在无水条件下，Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃能使NO的最大转化率高达84.3%，即使在275 ℃ 10%水蒸气存在的情况下，仍能使NO的转化率高达81.2%。     

复合固体超强酸催化剂SO2-4-WO3-ZrO2的结构研究

Solid superacid catalyst SO4(2-)-WO3-ZrO2 was characterized by means of XRD,DTA-TG, and surface area measurement techniques. The dependence of the surface area, SO42- content of the catalyst on calcination temperature was measured. It was found that there is a synergy to a certain degree between SO42- and WO3 with respect to the delay of ZrO2 crystallization, the stabilization of the tetragonal ZrO2 and the enlargement of the surface area of the catalyst. The addition of WO3 is beneficial to the stabilization of SO42- and remarkably increases the stability of SO42- at high temperature.     

Ti3+自掺杂的TiO2(A)/TiO2(R)/In2O3纳米异质结的制备与可见光催化性能

以TiCl₃和InCl₃为Ti源和In源,在不使用还原剂的条件下,首先通过液相沉淀反应制备前驱体沉淀,然后采用后续水热处理制备Ti³⁺自掺杂的TiO₂(A)/TiO₂(R)/In₂O₃纳米异质结,考察了水热处理温度对材料结构和性能的影响。利用X射线衍射、透射电子显微镜、X射线光电子能谱和紫外-可见漫反射光谱对样品进行表征。分别以罗丹明B和苯酚溶液为模拟废水评价了样品的可见光催化降解性能。结果表明,与纯的TiO₂、In₂O₃以及Ti³⁺自掺杂的TiO₂相比,Ti³⁺自掺杂的TiO₂(A)/TiO₂(R)/In₂O₃纳米异质结在可见光区有明显的吸收,并具有良好的可见光催化降解性能,200℃下水热处理24 h所得样品光催化降解罗丹明B的反应速率常数(0.0444 min^-1)分别是纯TiO₂和In₂O₃的17.76倍和8.71倍。瞬态光电流时间响应结果表明样品的光催化性能主要来源于TiO₂(A)/TiO₂(R)/In₂O₃纳米异质结导致的提高的光生电子和空穴分离效率。     

Ca2+-Mg2+-Zn2+体系在水溶性聚磷酸铵溶液中螯合规律的研究

近年来,水溶性聚磷酸铵在液体肥料和复合肥料的领域受到了广泛的关注,并在发达国家中得到了大面积的推广及应用。在pH值为5.5~8.0、温度为278.15 K~323.15 K的条件下,本文采用滴定法研究Ca_²⁺-Mg_²⁺-Zn_²⁺体系在聚磷酸铵溶液中的螯合规律。实验结果表明：相同质量分数的聚磷酸铵溶液对金属离子的螯合量会随着体系中Ca_²⁺、Mg_²⁺、Zn_²⁺的摩尔浓度的变化而变化;随着温度的升高而逐渐降低;随着pH的增加而逐渐增加;随着聚合度的升高而逐渐增加。采用傅里叶红外光谱对聚磷酸铵和A₁B₃C₃体系的螯合物进行表征。     

复合催化剂上CO2加氢合成C2烃类

介绍了由CO₂+H₂合成C2⁺烃的几种复合催化剂体系的研究进展，比较和评价了复合催化剂体系的活性和选择性及对C2⁺烃类生成的影响。着重于复合催化剂体系对C4⁺烃的生成及产物分布的影响并简述反应机理。