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以尿素为燃料,采用快速燃烧法在650℃合成了Tb3+掺杂的SrAl2O4:Eu2+,Dy3+新型长余辉光致发光材料。研究了Tb3+掺杂对Eu2+,Dy3+共激活的铝酸盐长余辉发光材料的发光特性的影响。X射线衍射分析结果表明:当Tb3+的掺杂量x=0.17%时,合成的样品结构为单相SrAl2O4单斜晶系。光致发光测试结果表明:样品的激发光谱为峰值位于345nm附近的连续宽带谱,发射光谱为峰值位于510nm左右的连续宽带谱。余辉衰减曲线结果表明:Tb3+的适量掺杂可以提高铝酸锶的余辉性能。与SrAl2O4:Eu2+,Dy3+相比,掺杂Tb3+有利于形成结晶度良好的固溶体,样品中的晶体细密紧凑,颗粒粒径约为100nm。 相似文献
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Influence of Microstructure Modulation of Er~(3+)-Doped Al_2O_3 on the Photoluminescence Performance
采用溶胶–凝胶法分别制备了掺不同摩尔分数Er3+的Er3+:Al2O3粉末和不同摩尔分数Y3+的0.5%Er3+:Al2O3(Y3+:0.5%Er3+:Al2O3)粉末。利用Y3+与Al3+的半径差异,通过共掺不同掺量的Y3+来调制Al2O3的微结构,用X射线衍射和透射电子显微镜分析样品的结构特征,并通过光致发光光谱研究样品的光致发光特性。结果表明:不同Y3+和Er3+共掺杂的Y3+:Er3+:Al2O3样品均以-Al2O3为主相;随着Y3+掺量的增加,Al2O3的晶格缺陷逐渐增多;样品的荧光强度、发射谱宽度及荧光寿命也都随着Y3+掺量增大而增大。通过Y3+掺量调制Er3+所处微结构环境的方法有效地改善了Er3+:Al2O3材料的发光特性。 相似文献
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用溶胶凝胶法制备了一系列不同掺杂浓度的Y3Al5O12(YAG):Tb3+,Ce3+荧光粉,对其物相、光学性能和能量传递进行了研究。多晶粉末X-射线衍射结果表明,所有样品均为YAG晶相,没有其它杂相。当样品在Tb3+的特征激发峰273 nm激发时,除了Tb3+的特征发射外,还观察到位于467 nm的YAG基质的电荷迁移带、位于520 nm的Ce3+的2D3/2,5/2→2F5/2,7/2跃迁,这说明可能存在Tb3+到Ce3+的单向非辐射能量传递。通过监测共掺样品520 nm的发光,得到273 nm的激发峰,使得Tb3+(5D3)到Ce3+(2Di,i=5/2,3/2)的单向非辐射能量传递得到验证;并且随着掺杂Tb3+浓度的增大,273 nm激发峰增强。同时,Ce3+掺杂YAG:Tb3+并没有使Tb3+发光增强,相反YAG:Tb3+,Ce3+中Tb3+发光与YAG:Tb3+相比有1个数量级的减弱,造成这种情况的可能原因,一是Tb3+到Ce3+的单向非辐射能量传递,使得Tb3+发光减弱;二是Ce3+掺杂YAG:Tb3+后基质所多吸收的能量传给了Ce3+而非Tb3+。 相似文献
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采用高温固相合成法研究了镓酸碱土体系的相关系及此体系的荧光性能。研究了以MGa2O4(M=Ba,Sr,Ca)为荧光粉的基质合成条件;探讨了MGa2O4(M=Ba,Sr,Ca)掺杂Eu3+、Tb3+等为激活剂的荧光粉的光致发光性能。 相似文献
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用高温固相法合成了颜色可调的SrMoO4:xEu3+,yTb3+荧光粉,并对其发光粉结构及其发光特性进行了研究。结果表明,SrMoO4:xEu3+,yTb3+荧光粉属于四方结构。Eu3+离子在SrMoO4晶体中形成峰值为617 nm的5d→4f跃迁发光,Tb3+离子的5 D4→7 F5跃迁产生548 nm的绿光发射。两个发射带的激发光谱范围位于250~450 nm处,SrMoO4:xEu3+,yTb3+在紫外、近紫外波段内有很强的激发,是一种适合InGaN芯片激发的白光LED用荧光粉。 相似文献
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为进一步揭示多稀土离子共掺低声子能量玻璃中Er3+的光谱特性及其发光机理,采用高温熔融法制备了Er3+/Yb3+/Ce3+共掺组分为(72.5–x)TeO2–20ZnO–5La2O3–0.5Er2O3–2Yb2O3–xCe2O3(x=0,0.4,0.7,1.0,摩尔分数x%)的碲酸盐玻璃,通过测量吸收光谱、荧光光谱和无掺杂样品的Raman光谱,以及计算相应能级间的吸收截面和受激发射截面,研究并分析了Yb3+和Ce3+离子掺杂对于Er3+的1.55μm波段荧光特性的影响。结果显示:Yb3+和Ce3+的引入能显著增强975nm泵浦下Er3+的1.55μm波段荧光强度。分析表明:Er3+在1.55μm波段荧光强度的增强主要归结于Yb3+/Yb3+、Yb3+/Er3+离子间的共振能量传递过程以及基于单声子和双声子辅助的Er3+/Ce3+离子间的能量传递过程,并通过计算得到了相应稀土离子间的能量传递微观参数和声子所作的贡献比。 相似文献
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Mg~(2+)、Sr~(2+)离子掺杂对Ca_2Li_2BiV_3O_(12):Eu~(3+)发光性能的影响 总被引:1,自引:0,他引:1
采用高温固相法合成了Mg2+、Sr2+离子掺杂新型Ca2Li2BiV3 O12:Eu3+红色荧光粉体材料,研究了保温时间对Ca2 Li2 BiV3 O12:Eu3+荧光粉的影响。使用X射线衍射仪对合成样品进行物相分析,利用荧光分光光度计进行光谱分析,测试了样品的荧光光谱。样品表现为Eu3+离子的特征发射,发光强度随着保温时间的增加而逐渐增强。同时研究了Mg2+、Sr2+离子掺杂对合成荧光粉光谱对合成样品的发光性能的影响,本研究发现Mg2+离子掺杂后样品发光效果明显强于Sr2+离子掺杂后样品的发光效果。 相似文献
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Properties of two high performance engineering thermoplastics, amorphous polyethersulfone (PES) and semicrystalline polyetheretherketone (PEEK), are discussed. Both resins can be processed by conventional techniques, compounded with high performance fibers, and have high service temperature (up to 300°C). Due to the amorphous character PES can be dissolved and spray coated into metals. 相似文献
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Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively. 相似文献
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采用固相合成法制备了(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54(α=0.1~0.5)系陶瓷,表征了该陶瓷的相组成和显微结构,测试了微波介电性能.结果表明:α=0.3时,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷为单相的新钨青铜结构固溶体.α>0.3时,相继出现了第二相BaLa2Ti4O12和La0.66TiO2.993.随α的增加,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷的相对介电常数(εr)先增大后有所波动,品质因数(Qf)先增大后减小,谐振频率温度系数(τf)单调减小.α=0.3时,在1 350℃烧结的陶瓷的微波介电性能最佳:εr=98.77,Qf=5184GHz,τf=10.9×10-6/℃,优于不掺杂的BaO-Sm2O3-TiO2陶瓷的. 相似文献
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This semicrystalline phase, originally named ‘calcium silicate hydrate(II)’ by Taylor (1950), has been studied with X-rays, electron optics, chemical investigation of silicate anion type, infrared spectra, and thermal methods. It is structurally related to jennite (C9S6H11) and probably also to the fibrous CSH of cement pastes, the three phases forming a sequence of decreasing crystallinity. The specimen studied had approximate composition C2SH3.2 after standing over saturated CaCλ2 at about 15°C. CSH(II) contains metasilicate chains and pyrosilicate groups and has a disordered layer structure. Much of the water can be lost reversibly without significant change in lattice parameters. 相似文献
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Summary In the present work we describe, the synthesis and characterization of a new gel obtained by crosslinking a cooligomer of butadiene-acrylic acid (BuAA), by reaction with acrylonitrile and acrylic acid. The purified product was characterized by FTIR, elemental analyses and scanning electronic microscopy. The thermal properties were studied and swelling indexes were determined in different solvents and at different pH values. The capacity of poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid) [gel A] to separate different organic substances, such as amino acids and colorants, was determined. 相似文献
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The addition of side groups to improve the photooxidative stability of polymers used in polymer-based light-emitting diodes (LEDs) is explored. Infrared spectroscopy and computational chemistry techniques are used to study the effects of chemical substitution of the reactive vinylene moiety in poly(phenylene vinylene) (PPV). The bond order of the vinylene group in small oligomers is calculated using semiempirical techniques to assess the improvement in stability toward oxidants such as singlet oxygen. We find that PPV dimers allow relative comparisons across a range of possible substitutions. Experimental results correlate well with these calculations. The addition of electron-withdrawing substituents, such as nitrile groups, to the vinylene moiety is found to be particularly effective in reducing the reactivity of alkoxy-substituted PPV toward singlet oxygen. The photooxidative stability of a poly(phenylene acetylene) (PPA) derivative is also studied. It appears that this family of polymers is more stable toward photooxidation than are its PPV analogs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2451–2458, 1998 相似文献
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Hybrid films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were prepared with different molecular weights of poly(ethylene oxide) (PEO). The cross-linking reaction between PEO and PEDOT:PSS was performed at high temperature and confirmed by using differential scanning calorimeter (DSC), contact angle measurement, and solid-state 1H NMR. The effect of chemical reaction on the conductivity and morphology of these hybrid films was studied by using 4-point probe and atomic force microscope (AFM), respectively. As-spun PEO/PEDOT:PSS films have lower electric conductivity due to the addition of nonconductive PEO, and exhibits no molecular weight dependence on conductivity. After chemical cross-linking reaction at high temperature, only PEDOT:PSS films with lowest molecular weight PEO additives show enhanced conductivity with increasing reaction time. AFM result indicates that the heat-treated PEO/PEDOT:PSS hybrid films show grain-like morphology compared to ethylene glycol treated PEDOT:PSS films which shows continuous PEDOT domain. In the present work we demonstrate that the cross-linking reaction can be used to improve the wet stability of PEDOT:PSS nanofiber, showing good water resistance and excellent dimensional stability. 相似文献
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Witold Brostow Kwan-Ho Seo Jong B. Beak Jeong C. Lim Kwan-Ho Seo 《Polymer Engineering and Science》1995,35(12):1016-1021
The miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures Tg of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control Tg and melting temperature Tm of PPS by varying amounts of PPSE in blends. The melt crystallization temperature Tmc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE. The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ?2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases. 相似文献