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1.
在Sm2O3掺杂BaO-B2O3-Al2O3-SiO2-Sm2O3(BBASS)玻璃系统的形成性能的研究基础上,借助MAS NMR以及差热测试技术,研究了玻璃的结构特点以及玻璃组成、热处理条件等因素对玻璃结构的影响。研究表明,在未掺稀土的BBAS玻璃结构中,硼氧多面体主要以[BO3]、[BO4]存在,铝氧多面体主要以[AlO4]、[AlO5]、[AlO6]存在;随着BBAS中BaO含量的增加,硼氧三角体[BO3]逐渐向[BO4]转变,铝氧多面体中的[AlO5]、[AlO6]结构单元逐渐向[AlO4]转变;稀土Sm3+具有较强迫积聚作用,能促使玻璃结构中的硼氧多面体形成巨大的网络结构;热处理对玻璃结构中硼氧多面体和铝氧多面体的配位结构影响不大。 相似文献
2.
The photosensitive effect of Ce on the precipitation of Ag nanoparticles induced by femtosecond laser in silicate glass 下载免费PDF全文
This paper studies the photosensitive effect of cerium oxide on the
precipitation of Ag nanoparticles after femtosecond laser
irradiating into silicate glass and successive annealing.
Spectroscopy analysis and diffraction efficiency measurements show
that the introduction of cerium oxide may increase the concentration
of Ag atoms in the femtosecond laser-irradiated regions resulting
from the photoreduction reaction Ce3+ + Ag+ \to
Ce3+ + Ag0 via multiphoton excitation. These results
promote the aggregation of Ag nanoparticles during the annealing
process. It is also found that different concentrations of cerium oxide
may influence the Ag nanoparticle precipitation in the
corresponding glass. 相似文献
3.
Undoped and cerium doped Calcium sulfide (CaS) phosphors were synthesized using solid state diffusion method. The X-ray diffraction pattern revealed that both undoped and doped CaS crystallites have cubic structure with average crystallite size varying from 20 to 30 nm. Scanning electron micrographs indicated that Ce doped CaS phosphors were composed of whiskers with different dimensions and orientations. The optical properties of undoped and Ce doped particles were characterized using Photoluminescence (PL) and UV-Vis absorption spectroscopy. The PL emission spectrum of cerium doped CaS phosphors for an excitation wavelength 465 nm showed a main peak at 500 nm and a shoulder peak at 556 nm due to 5d?→?4f transition in Ce3+ ions. The variation of PL intensity with cerium concentration was investigated and the maximum PL intensity was obtained for a doping concentration of 3 wt.%. The optical band gap of the samples was estimated from the diffuse reflectance spectrum and was found to increase with increase in cerium concentration. The enhanced optical properties of these phosphors can be exploited in various optoelectronic devices including displays and bioimaging techniques. 相似文献
4.
Kaushik Mallick Michael Witcomb Rudolph Erasmus André Strydom 《Journal of Macromolecular Science: Physics》2013,52(1):134-141
Paramagnetism in polyaniline can be generated during synthesis if cerium (IV) ammonium nitrate (CAN) is used as a polymerizing (oxidizing) agent. During the reaction, in situ formation of Ce3+ ions are doped in the spherical polyaniline particles and show paramagnetic behavior throughout the experimental temperature range (400–1.9 K). The result indicated that the Ce3+ ions covalently functionalized with the chain nitrogen of the polyaniline. 相似文献
5.
Creep cavitation in materials is greatly influenced by trace elements. To enhance creep cavitation resistance, the chemical composition of 304, 321, 347 austenitic stainless steels was modified with the addition of minute amounts of boron and cerium. The addition of boron and cerium to type 304 stainless steel led to an increase in its creep rupture life with an associated decrease in creep rupture ductility. The addition of boron and cerium to the titanium-containing 321 steel and niobium-containing 347 steel was found to increase their creep rupture life and ductility. Creep cavitation was highly suppressed in the 347 and 321 steels with the addition of boron and cerium. The chemistry of the grain boundary and creep cavity surface was analyzed by Auger electron spectroscopy. Extensive sulphur segregation was observed on the grain boundary and cavity surface of the steels without boron and cerium addition and even in the 304 steel containing boron and cerium. In the boron- and cerium-containing 347 and 321 steels, respectively, segregation of elemental boron and the BN compound on the cavity surface were observed. These segregations reduced cavity growth rate substantially in these steels and BN segregation was found to be more effective in reducing cavity growth rate than boron segregation. Cerium acts as a getter for soluble sulphur in the steels by precipitation of ceriumoxysulfide (Ce2O2S) to facilitate the segregation of boron on the cavity surface. 相似文献
6.
稀土掺杂硼铝硅酸盐玻璃结构的NMR研究 总被引:3,自引:0,他引:3
在Sm2O3掺杂BaO-B2O3-Al2O3-SiO2-Sm2O3(BBASS)玻璃系统的形成性能研究的基础上,借助MAS NMR以及差热测试(DTA)技术,研究了玻璃的结构特点以及玻璃组成、热处理条件等因素对玻璃结构的影响. 研究表明,在未掺稀土的BBAS玻璃结构中,硼氧多面体主要以[BO3]、[BO4]存在,铝氧多面体主要以[AlO4]、[AlO5]、[AlO6]存在;随着BBAS中BaO含量的增加,硼氧三角体[BO3]逐渐向[BO4]转变,原先[AlO4]、[AlO5]、[AlO6]共存的铝氧多面体结构逐渐转变为大量[AlO4]和少量[AlO5]共存的结构;稀土Sm3+具有较强的积聚作用,其能促使玻璃结构中的硼氧多面体形成巨大的网络结构;热处理对玻璃结构中硼氧多面体和铝氧多面体的配位结构影响不大. 相似文献
7.
硼酸盐玻璃中某些稀土离子的浓度效应及其能量传递过程 总被引:2,自引:0,他引:2
本文系统地报道了硼酸盐玻璃中Ce3+、Sm33+、Eu3+、Ga3+、Tb3+、Dy3+浓度效应,观察到Eu3+、Gd3+、Tb3+在硼酸盐玻璃中随浓度增加其发光强度增强,而Ce3+、Sm3+、Dy3+当其浓度增加到一定数值后,发光强度反而减弱,初步探讨了不同浓度效应的原因.本文还观察到硼玻璃中某些稀土离子对Eu3+、Tb3+离子发光的敏化作用,及讨论了Gd3+和Eu3+、Tb3+之间的能量传递过程,计算其能量传递的效率和几率.估计了能量传递的规律机理. 相似文献
8.
A.A. Dakhel 《Current Applied Physics》2012,12(1):1-6
Thin films of boron and hydrogen-codoped CdO (B&H-codoped CdO) oxide with different boron content have been prepared on glass and silicon substrates. The effects of codoping on the structural, electrical, and optical properties of the host CdO films were systematically studied. The structural study shows that doped boron ions occupied locations in interstitial positions and/or Cd2+-ion vacancies of CdO lattice. The bandgap of B-doped CdO shrinks by 25-38% compare to hydrogenated CdO. Such bandgap narrowing was phenomenological studied in the framework of the available models. The electrical behaviours show that all the prepared B&H-doped CdO films are degenerate semiconductors. However, the hydrogenated 7.9% boron doped CdO has resistivity of 1.52 × 10−4 Ω cm, mobility of 47.5 cm2/V s, and carrier concentration of 8.6 × 1020 cm−3. The optoelectronic measurements in visible and NIR spectral range demonstrate the utility of the oxide/p-Si heterojunction in photodetection applications. 相似文献
9.
合成了铕离子激活的MMgF4.磷光体,研究了Eu3+离子的光谱特征与基质化合物的关系,存在三类发光中心,讨论了基质组成对铕离子价态的影响。 相似文献
10.
T. Satoh Y. Kikuchi K. Miyano E. Pollert J. HejtmÁnek Z. JirÁk 《Phase Transitions》2013,86(7-8):935-940
Irreversible photoinduced insulator-metal transition has been observed in a perovskite manganite doped with monovalent Na + , Pr 0.75 Na 0.25 MnO 3 . The increase of the conductance is estimated to be of the order of 10 4 -10 5 , considering the shallow penetration depth ( ¨ 0.1 µm) of illumination light. Analysis of the dc- and ac-susceptibility data shows that the system is in a cluster glass state below 45 K, which means that ferromagnetic metallic clusters exist in insulating matrix. The photo-excitation helps the clusters to dislodge from a local energy minimum and to seek more stable configuration. The observed large increase of the conductivity can be well explained by the percolative conduction. We argue that metastability is due to the large charge mismatch between the monovalent Na + ion and trivalent Pr 3+ ion or the deviation of the average Mn valency from 3.5+. 相似文献
11.
12.
掺铜磷酸盐和氟磷酸盐玻璃的光谱研究 总被引:1,自引:1,他引:0
本文对掺铜Ca-Al磷酸盐玻璃和、Na-Mg-Ca-Sr-Ba-Al氟磷酸盐玻璃分别作了吸收光谱、ESR谱、激发光谱、荧光光谱和荧光寿命测定。实验结果表明,玻璃中的Cu2+在近红外有一吸收带,属于畸变0h格位中2Eg→2T2g的跃迁。Cu+在紫外区有一吸收带,属于3d10→3d94s1跃迁。用紫外激发,玻璃中Cu+在可见区有一较宽的发光带。磷酸盐玻璃中,荧光峰值位于458nm。氟磷酸盐玻璃中,荧光峰值位于420nm。前者荧光寿命为26μs,后者为60μs。 相似文献
13.
采用低温熔融法制备了有机染料芪3掺杂的不同浓度的铅-锡-氟磷酸盐玻璃,通过对掺杂玻璃激发光谱、发射光谱和吸收光谱的测试,研究了芪3在无机玻璃中的聚集状态和光谱性能。 结果表明,有机染料芪3以单体和二聚物的形式共存于无机玻璃中,和芪3单体分子的激发峰相比,二聚物的激发峰位于短波段,随掺杂浓度的增加,掺杂玻璃的发射峰发生红移,同时在荧光光谱中观察到浓度猝灭现象;芪3分子与无机玻璃通过亲水作用发生了键合,从而导致芪3在无机玻璃中的吸收光谱和发射光谱比在乙醇溶液中出现较大红移;与芪3在乙醇溶液中的荧光强度相比,芪3分子受无机玻璃的“笼”化作用有效的提高了其荧光强度。 相似文献
14.
15.
A series of Ce-TiO2 are prepared by the sol-gel process with ammonium cerium(IV) nitrate and tetra-n-butyl titanium as raw materials and characterized with XRD, TEM, DRS, and XPS. The aberrance (0.355) of anatase(1 0 1) plane of 0.1% Ce/TiO2 increases compared to that of TiO2. Cerium is found to be present as a mixture of Ce3+/4+ oxidation states, that is, the oxidation state of some cerium in Ce-TiO2 has changed after calcination. Ce/TiO2 yields a large red shift compared to TiO2. Moreover, the reflectance decreases in the visible region after cerium doped on TiO2, and the lower the reflectance the higher the activity. Cerium appears to enhance the photocatalytic activity of Ce/TiO2 by suppressing electron-hole recombination with electron trapping at Ce4+. 0.1% Ce/TiO2 shows highest activity for the degradation of aqueous suspension of formaldehyde. 相似文献
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17.
Sm3+ doped CaO-MgO-Al2O3-SiO2 glass and glass ceramics have been prepared. The diopside crystal (CaMgSi2O6) was identified in the glass ceramics by X-ray diffraction analysis. X-ray photoelectron spectra of the glass and glass ceramics were measured by a monochromatised Al-Kα XPS instrument. Sm 3d core level spectra for the Sm doped samples showed that Sm ions are predominantly in the Sm (III) state in glass and glass ceramics. The O 1s core spectra could be fitted by summing the contributions from bridging oxygen (BO) and non bridging oxygen (NBO) for samarium undoped glass, BO, NBO and Si-O-Sm for the doped glass. The O 1s XPS spectrum of undoped glass ceramics was curve fitted with BO and NBO in glass phase, as well as SiOSi, SiOMg and SiOCa in diopside. In addition to the five components above mentioned, SiOSm in diopside also appeared in O 1s XPS spectra of samarium doped glass ceramics. According to the fitting results, we demonstrate that the Sm2O3 exist in glass network as a glass modifier. After heat treatment, nearly all the Sm3+ existed in diopside phase as the substitution for Ca2+. 相似文献
18.
合成了铕离子激活的MMgF4.磷光体,研究了Eu3+离子的光谱特征与基质化合物的关系,存在三类发光中心,讨论了基质组成对铕离子价态的影响. 相似文献
19.
It is suggested that molecules containing cerium ions with a formal valency +4 may form a ground state resembling a Kondo singlet. This is demonstrated explicitly by choosing cerocene as an example. Experimental consequences for these systems are discussed. 相似文献
20.
Single crystals of pure and cerium(III)nitrate doped zinc(tris) thiourea sulphate (ZTS) were grown from aqueous solution by slow evaporation method. The cell parameters of the grown crystals were determined by single crystal X-ray diffraction analysis. Powder X-ray diffraction patterns were recorded and indexed for the structural confirmation. The presence of functional group in the compound has been confirmed by FTIR analysis. UV–vis absorption spectrum has been recorded to determine the cut-off wavelength of the crystal. TGA/DTA studies show thermal stability of the grown crystals. SEM-EDX analysis revealed the incorporation of the impurity (Ce3+) into ZTS crystals. The microhardness study reveals that the hardness number (Hv) increases with load for all the grown crystals of this work. From the values of work hardening coefficients, it was concluded that pure and cerium nitrate doped ZTS crystals belong to the category of soft materials. The second harmonic generation of cerium(III)nitrate doped ZTS crystals was confirmed by Kurtz–Perry powder method using Nd:YAG laser. 相似文献