共查询到19条相似文献,搜索用时 15 毫秒
1.
A novel process for separation of red (Y2O3: Eu3+), blue (Sr, Ca, Ba)10(PO4)6Cl2: Eu2+ and green (LaPO4: Tb3+, Ce3+) fine tricolor phosphor powders was established. First, the green phosphor was extracted and separated from three phosphor
mixtures in heptane/DMF(N, N-Dimethylformamide) system using stearylamine or laurylamine (DDA) as the cationic surfactant.
Then, after being treated with 99.5% ethanol, the blue and red phosphors could be separated in Heptane/DMF system in presence
of 1-octanesulfonic acid sodium salt as the anionic surfactant. Satisfactory separation results have been achieved through
two steps extractions with their artificial mixtures. The grades and recovery of separated products reached respectively as
follows: red product was 95.3% and 90.9%, blue product was 90.0% and 95.2%, and green product was 92.2% and 91.8%.
Funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (ROCS, SEM
[2005] No. 383) 相似文献
2.
采用改进的共沉淀法合成掺Eu3+铝酸锌荧光粉。对产物进行X射线衍射和发光性能分析。X射线衍射分析结果表明,在Eu3+掺杂质量分数低于5%时,掺Eu3+铝酸锌的结晶质量高;但当Eu3+掺杂质量分数高于5%时,会导致晶体结构缺陷的数目增加,从而引起结晶质量下降。不同掺杂浓度的荧光粉的发射光谱显示,当掺杂质量分数高于5%时,会出现浓度猝灭现象。与固相反应法相比,共沉淀法的猝灭浓度有明显提高。 相似文献
3.
采用高温固相法合成了BaZn1.06Al9.94O17:Tb3+,Ce3+荧光粉,并对其发光性能和能量传递机理进行了研究.研究结果表明:由于Tb3+离子的4f8 → 4f75d1跃迁,使得BaZn1.06Al9.94O17:Tb3+的激发带中心位于230 nm处.共掺杂Ce3+离子后,BaZn1.06Al9.94O17:Tb3+的激发光谱出现了明显的红移,在240~320 nm范围内的宽带激发归因于Ce3+离子的4f → 5d跃迁.由于Ce3+与Tb3+离子发生了能量传递,使得BaZn1.06Al9.94O17:Tb3+,Ce3+中Tb3+离子的5D4 → 7FJ(J=6、5、4和3)发射峰的发光强度比未掺杂Ce3+离子时提高了约15倍.因此,制备的BaZn1.06Al9.94O17:Tb3+,Ce3+荧光粉可望在照明、显示器件等应用中具有良好的应用价值. 相似文献
4.
采用高温固相法在弱还原气氛下制备了系列荧光粉材料Sr1-3(x+y)/2Al2Si2O8:xCe3+,yTb3+,并通过X射线衍射(XRD)、荧光光谱和荧光强度比(FIR)测温法分析了荧光粉样品的晶体结构、发光性能及其温度传感特性。XRD分析结果表明掺杂离子Ce3+和Tb3+均占据Sr2+格位,并且掺杂少量的稀土离子不会改变基质的晶体结构。荧光光谱分析结果表明在近紫外光激发下,该双掺杂荧光粉的发射光谱显示出Ce3+和Tb3+离子的特征发射峰,最佳掺杂浓度的荧光粉化学式为Sr0.865Al2Si2O8:0.05Ce3+,0.04Tb3+。此外,在不同波长的监测下,测得的激发光谱形状十分相似,表明在该荧光粉中存在着Ce3+→Tb3+能量传递过程。FIR测温法计算结果表明该荧光粉的相对灵敏度随温度的升高而升高,在520 K时有最大值为0.022 4 K-1。研究结果表明该荧光粉具备的优异光学性能和温度传感性能使其成为一种具有应用前景的测温材料。 相似文献
5.
以自然界中多种多样、复杂精细的生物结构为模板,即通过生物模板法,可制备出具有类似结构的人工材料以提高材料性能或探索材料新的性质。本研究以具有精细二维光子晶体结构的绿斑德凤蝶(Papilio epiphorbas)鳞片为模板,采用以水溶胶凝胶为前驱体的生物模板法成功制备出具有精细二维光子晶体结构的Y2O3:Eu3+荧光体。场发射扫描电镜对仿生Y2O3:Eu3+进行了结构表征,证明仿生Y2O3:Eu3+可以完好地复制蝴蝶鳞片的二维光子晶体结构;采用激光共聚焦显微拉曼光谱仪对仿生Y2O3:Eu3+进行了光致发光测试,证明Eu3+充分掺杂使荧光体产生了特征荧光。通过水溶胶前驱体工艺和水溶液前驱体工艺的对比研究,证明了以水溶胶为前驱体的生物模板法在制备精细结构材料上的优势,对精细结构材料的生物模板法制备具有重要参考价值。 相似文献
6.
ZHANGLi CHENShu W.D.Schubet HUANGBai-yun 《中南工业大学学报(英文版)》2004,11(2):119-123
Ultrafine tungsten carbide and fine cobalt as well as nano yttrium oxide powders were used as the raw materials. The effects of hot-press below the eutectic temperature and conventional liquid phase sintering on the structures and properties of WC-20Co-1Y2O3 cemented carbide were studied. It is shown that hot-pressed alloy has the character of isotropic properties and microstructure with homogeneous and ultrafine WC grains. However, the ultrafine and fully-densified structure is developed at the cost of the presence of large amount of cobalt-lake (uneven-ly distributed binder phase), and thus lower strength. Yttrium oxide in the alloy cannot play the role of grain growth inhibitor fully when cemented carbide with high content of cobalt and ultrafine raw materials is sintered at high liquid phase sintering temperature. Peculiar platelet-enhanced bi-model structure is formed in WC-20Co-1Y2 O3 cemented carbide by conventional liquid phase sintering, which points out that yttrium oxide in the alloy facilitates the formation of plate-like WC grain. 相似文献
7.
采用沉淀法合成了YVO4:Eu3+,Bi3+荧光粉,利用XRD,SEM和TEM对样品的结构和形貌进行表征,并用荧光光谱仪测试了样品的激发和发射光谱。X射线衍射图分析表明,所制得的荧光粉与YVO4的物相一致,样品属于体心四方相。其扫描电镜和透射电镜照片显示颗粒为纺锤形,大小比较均匀,长径为250nm左右,短径为100nm左右。在275nm近紫外光激发下,该荧光粉的发光峰分别归属于Eu3+的5 D0→7 F1(596nm),5 D0→7F2(617nm,621nm),5 D0→7F3(654nm),5 D0→7F4(702nm)辐射跃迁。最强发射位于617nm左右,属于红光。研究了Eu3+浓度对样品发光强度的影响。随着Eu3+浓度的增加,发射峰强度增大,当Eu3+摩尔分数为12%时,峰值强度最大。Bi3+对Eu3+的发光有一定的敏化作用,当Bi3+摩尔分数达到5%时,敏化作用最强。 相似文献
8.
以β-丙氨酸和尿素为燃料,采用溶液燃烧法在低温450℃下合成制备了Ca3Al2O6:Eu3+荧光粉。样品的发射光谱由位于594 nm、617 nm、653 nm及700 nm处的4组线状峰构成,分别对应Eu3+的5D0→7Fj(j=1~4)特征跃迁,其中617 nm处的峰最强,样品呈现红色发光。考察了Eu3+掺杂浓度对晶体结构和发光性能的影响。结果呈示:随着掺杂浓度的增加晶格常数逐渐减小,[O—Al—O]的对称伸缩振动Raman峰蓝移;在低掺杂浓度时荧光强度逐渐增大,掺杂6%时达到最大,之后出现浓度猝灭现象,猝灭机制为交互作用;Eu3+的5D0→7F2与5D0→7F1跃迁强度比随着掺杂浓度的增加逐渐增大,掺杂的Eu3+主要取代处于非对称中心的Ca2+。 相似文献
9.
郝艳 《武汉理工大学学报(材料科学英文版)》2015,(1):97-99
New phosphors Sr2 Zn Si2O7: M(M=Mn2+, Tb3+) were synthesized through solid-state reaction, and their photoluminescent properties under UV and VUV region were investigated. The results showed that Sr2 Zn Si2O7:Mn2+ emitted green light with the strongest emission peak centered at 525 nm, and its quenching concentration under 254 and 147 nm excitation occurred at x = 0.08 and 0.06, respectively. Sr2 Zn Si2O7: Tb3+ emitted green light with the strongest emission peak centered at 541 nm, and its quenching concentration under 254 and 147 nm excitation also appeared at y = 0.25. At 147 nm excitation, the emission intensities of Sr2Zn0.94Si2O7: 0.06Mn2+ and Sr1.75 Zn Si2O7: 0.25Tb3+ phosphors were 54% and 36% of that of Zn1.96 Si O4:0.04Mn2+, respectively. And their decay times(τ1/e) were about 3.18 ms and 3.9 ms, respectively. 相似文献
10.
采用高温固相法合成了系列LaSrZnNbO6:Bi3+,Sm3+荧光粉,并对其发光性质以及Bi3+、Sm3+离子间的能量传递机理进行了研究.结果显示,当以Bi3+的1S0→ 3P1激发位置(338 nm)激发Bi3+和Sm3+共掺杂LaSrZnNbO6荧光粉时,在LaSrZnNbO6荧光粉的发射光谱中同时出现了Bi3+和Sm3+的发射峰,表明在LaSrZnNbO6基质中存在Bi3+→ Sm3+的能量传递.经计算, Bi3+离子和Sm3+离子间的能量传递效率可达到86.9%.通过改变Bi3+离子和Sm3+离子的掺杂浓度可以使LaSrZnNbO6荧光粉的CIE色坐标由蓝光区域移动至粉白光区域,表明通过调节掺杂浓度可制备出颜色可调谐的荧光粉. 相似文献
11.
为了探究稀土离子掺杂铝硅酸盐的光温特性,本文采用燃烧合成法制备了系列荧光粉材料Ca1-3x/2Al2Si2O8:xEu3+。X射线衍射结果表明掺杂Eu3+离子不会改变基质CaAl2Si2O8的晶体结构。荧光光谱结果表明该荧光粉在近紫外光区域具有较强吸收,当被波长为393 nm的近紫外光激发后,其最大特征发射峰为611 nm,且Eu3+离子的最佳掺杂浓度为0.05。利用上升时间测温法研究了CaAl2Si2O8:Eu3+荧光粉的光温传感特性,结果表明:随着Eu3+掺杂浓度的增加,上升时间单调递减,但当掺杂掺杂超过0.100时就会发生淬灭。Ca0.985Al2Si2O8:0.01Eu3+的相对灵敏度随温度的升高先增大后减小,并在520 K时达到最大值(0.024 K-1)。上述研究表明该荧光粉具备优异的温度传感性能,在测温领域具有广泛的应用前景。 相似文献
12.
NiCrAlY+(ZrO2+Y2O3) thermal barrier coating was prepared on the surface of refractory steel 1Cr18Ni9Ti with plasma spraying technique. The phases
and microstructure of the thermal barrier coating were determined by scanning electron microscopy (SEM) and X-ray diffraction
(XRD). The results show that the bonding between thermal barrier coating and substrate is sound. The surface hardness of 1Cr18Ni9Ti
reaches up to 1 000 HV, but that of substrate is only 300 HV. The patterns sprayed with CoNiCrAlY+(ZrO2+Y2O3) ceramic coating have a good heat insulation effect at 800 °C for heat insulation temperature difference reaches 54 °C, which
increases the operating temperature and service life of refractory steel.
Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education 相似文献
13.
LaF3:Yb3 +,Er3 + nanoparticles were successfully synthesized using solvothermal treatment,and LaF3:Yb3 +,Er3 +/SiO2 core/shell nanoparticles were also prepared with reverse microemulsion technique.The... 相似文献
14.
尖晶石 LiMn2O4 正极材料是在原有锂电池正极材料 LiCoO2 、LiNiO2 、LiMnO2 的基础上研发出来的优选
正极材料, 它相较于 LiCoO2 材料价格更加低廉热稳定性加强且安全性能有所提高。采用 Mg2+ 掺杂 LiMn2O4正极
材料, 利用基于密度泛函理论的第一性原理对 LiMg0.5Mn1.5O4 晶格常数与能带结构、态密度进行计算与分析。结
果表明: 新材料 LiMg0.5Mn1.5O4 的空间群为 F4332, 掺杂后晶胞参数 a 明显减小, 晶胞体积收缩; 掺杂量为 0.5 时明
显比掺杂量 0.125 时 Fermi 能量和能量密度高。Mg 2+ 掺杂能影响 LiMn2O4 的晶体结构, 形成更加稳定的共价键。
掺杂量会改变 LiMn2O4 的空间群影响到结构稳定性, 所以掺杂量不宜过大。 相似文献
15.
The corrosion resistance of NiCrAl+(ZrO2+Y2O3) thermal barrier coating, formed with the plasma spraying technique, on the 18 - 8 steel surface was investigated. The phase
structure and morphology of the coating were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy
(SEM). The electrochemical corrosion behavior of the coating in 1.0 mol/L H2SO4 solution was studied by using electrochemical measurement methods. The results show that the gradient plasma spraying coating
is composed of the NiCrAlY coating and the (ZrO2+Y2O3) top coating, and the coating thickness is 360 μm. The microhardness of coating reaches 1 100 HV. The corrosion resistance of the plasma sprayed coating of the 18 - 8 steel
surface is about 5 times as great as that of the original pattern. The corrosion resistance of the coating is enhanced notably.
Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education 相似文献
16.
Yuhong Chen Zhiyuan Tang Guoqing Zhang Xuemei Zhang Ruizhen Chen Yuangang Liu Qiang Liu 《武汉理工大学学报(材料科学英文版)》2009,24(3):347-353
Mg3(PO4)2-coated Li1.05Ni1/3Mn1/3Co1/3O2 cathode materials were synthesized via co-precipitation method. The morphology, structure, electrochemical performance and
thermal stability were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry(CV),
electrochemical impedance spectroscopy(EIS), charge/discharge cycling and differential scanning calorimeter (DSC). SEM analysis
shows that Mg3(PO4)2-coating changes the morphologies of their particles and increases the grains size. XRD and CV results show that Mg3(PO4)2-coating powder is homogeneous and has better layered structure than the bare one. Mg3(PO4)2-coating improved high rate discharge capacity and cycle-life performance. The reason why the cycling performance of Mg3(PO4)2-coated sample at 55 °C was better than that of room temperature was the increasing of lithium-ion diffusion rate and charge
transfer rate with temperature rising. Mg3(PO4)2-coating improved the cathode thermal stability, and the result was consistent with thermal abuse tests using Li-ion cells:
the Mg3(PO4)2 coated Li1.05Ni1/3Mn1/3Co1/3O2 cathode did not exhibit thermal runaway with smoke and explosion, in contrast to the cells containing the bare Li1.05Ni1/3Mn1/3Co1/3O2.
Funded by the National Natural Science Foundation of China (No. 20273047) 相似文献
17.
LI Yuan WU Shunhua SU Hao WANG Xiaoyong 《武汉理工大学学报(材料科学英文版)》2008,23(2):143-146
The structures and dielectric properties of Ba6-3xNd8+2xTi18O54 system(x=2/3) doped with different contents of Bi2O3, whose final molecular formula is Ba6-3x(Nd1-yBiy)8+2xTi18O54 were investigated. It is indicated that the dielectric constant increases greatly whereas Q value(f0=4 GHz) decreases with the increase of Bi2O3 content. However, the temperature coefficient could be controlled below 0±30×10^-6/℃ in the experiment. These phenomena are related to the appearance of a new phase, Bi4Ti3O12, which has high dielectric constant. Also, that Bi^3+(0.13 nm) substitutes for Nd^3+(0.099 5 nm) will increase the unit cell volume, which will lead to the enlargement of the octahedron B site occupied by Ti^4+. So the spontaneous polarization of Ti^4+ ions will be strengthened. Besides, Bi^3+ will fill up some vacancies which Ba^2+ or Nd^3+ ions leave in two A1 sites and four A2 sites. More positive ions polarize, which also contributes to higher dielectric constant. The samples got with the optimium properties are sintered at 1 200 ℃ for 4 h, when y=0.25, ε≈110, Q≈5 400(f0=4 GHz), TCC=-4.7×10^-6/℃; When y=0.3, ε≈120, Q≈5 000(f0=4 GHz), TCC=-24×10^-6/℃. 相似文献
18.
Fine Al(OH)3 crystals were aggregated from supersaturated aluminate solution in the batch reaction tanks. By means of laser particle size analyzer and scanning electron microscopy, the influences of temperature and initial molar ratio of Na2O to Al2O3 (aK) on agglomeration of fine seed in Bayer process were investigated. The results show that agglomeration is almost finished in 8 h, and seeds with size less than 2 μm are easily aggregated together, and almost disappear in 8 h under the optimal process conditions. In the aluminate solution with the same moderate initial aK, when the reaction temperature reaches 75 ℃, the secondary nucleation does not occur, and the effect of agglomeration is better. And at the same reaction temperature, when the initial aK is 1.62, the initial supersaturation of aluminate solution is moderate, the binders on the surfaces of the seed are enough to maintain the agglomeration process, and the agglomeration degree is better. From SEM images, agglomeration mainly occurs in the fine particles, the combinations among the fine particles are loose and the new formed coarse crystal shapes are irregular. 相似文献
19.
Polycrystal of GdPO4:RE3+ (RE=Tb, Tm) phosphors were prepared by solid-state method. Vacuum ultraviolet excitation and emission spectrum and the energy
transfer mechanism between the host and dopants of Tb3+ and Tm3+ were investigated respectively. The emission of Gd3+ at 313 nm was enhanced by the strong absorption of CTS of Tm3+ at 180 nm in GdPO4: Tm. It has also been concluded that the excitation of Gd3+ is transferred to Tb3+ and then emission peaks of 5DJ→7FJ of Tb3+ were observed. 相似文献