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131.
Green light emitting Mn2+ doped Zn2SiO4 particles embedded in SiO2 host matrix were synthesized by a sol–gel method. After the incorporation of ZnO:Mn nanoparticles in a silica monolith using sol–gel method with supercritical drying of ethyl alcohol in two steps, it was heat treated in air at 1200 °C for 2 h in order to obtain the SiO2/α-Zn2SiO4:Mn nanocomposites. The microstructure of phosphor crystals was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD results indicate that the pure phase α-Zn2SiO4 with rhombohedral structure was obtained after thermal treatment at 1200 °C. The SiO2/α-Zn2SiO4:Mn nanocomposites with a Mn doping concentration of 1.5 at% exhibit two broadband emissions in the visible range: a strong green emission at around 525 nm and a second one in the range between 560 and 608 nm. This nanocomposite with a Mn doping concentration of 0.05 shows the highest relative emission intensity. Upon 255 nm excitation, the luminescence decay time of the green emission of Zn2SiO4:Mn around 525 nm is 11 ms. The luminescence spectra at 525 nm (4T1–6A1) and lifetime of the excited state of Mn2+ ions-doped Zn2SiO4 nanocrystals are investigated. 相似文献
132.
Spectra of 107Ag18O and 107Ag16O molecules have been obtained in a low-pressure arc in oxygen atmosphere, and recorded with medium dispersion. Vibrational assignments for the bands of B 2π —X2π system were verified by the study of the oxygen isotope effect, and the vibrational constants were obtained for the states involved in transitions. 相似文献
133.
采用乘积近似法计算了氧化亚氮分子的总配分函数,其中转动配分函数考虑了离心扭曲修正,振动配分函数采用谐振子近似. 利用计算所得的配分函数和实验振动跃迁矩平方及Herman-Wallis因子系数,计算了氧化亚氮3000—0200和1001—0110跃迁带在常温和高温下的线强度. 结果显示,当温度高达3000K时,计算所得线强度与实验值及HITRAN数据库提供的结果仍符合较好. 这表明高温下的分子配分函数和线强度的计算是可靠的. 还进一步计算了氧化亚氮3000—0200和1001—0110跃迁带在更高温度(40
关键词:
氧化亚氮
配分函数
线强度
高温 相似文献
134.
135.
The interaction between submonolayer titania coverages and Pt foil has been studied by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). The submonolayer titania can be fully oxidized to TiO2 at 923 K under 10−8 Torr O2, and partially oxidized to TiOx at lower oxidation temperatures. The oxidized surface can be reduced by annealing to 1000 K or higher, or by heating in H2 at 823 K, or by interacting with surface carbon formed from acetone decomposition. Under certain conditions (e.g., hydrogen reduction at 923 K), the surface titania can be fully reduced to metallic Ti which diffuses into bulk Pt readily. The reduced metallic Ti can resurface when the surface is oxidized at 923 K. Both XPS and HREELS data indicate the existence of subsurface oxygen, which plays an important role for the diffusion of Ti into and out of the Pt foil. Although no special interfacial active sites were revealed by HREELS studies of adsorbed acetone and CO, some TPD and XPS data suggest the presence of sites active for acetone decomposition. 相似文献
136.
在PVA溶液中制备ZnO∶Cu纳米粉体的前驱体,经过煅烧获得ZnO∶Cu纳米粉体,考察煅烧温度对制备过程及发光性能的影响。利用XRD、TEM分析了产物的结构和形貌,XRD分析结果表明,当煅烧温度高于500℃时,可以使PVA完全分解,制备出具有六角纤锌矿结构的ZnO∶Cu粉体。TEM结果表明,粉体呈球形,大小均匀,分散性好,平均粒径为20~25 nm。在342 nm波长光的激发下,在ZnO∶Cu的室温PL光谱中可以观察到两个中心波长位于458 nm和486 nm的较强的蓝光发射峰,经400℃煅烧处理的ZnO∶Cu纳米粉体的蓝光发射最强。煅烧后的ZnO∶Cu只有微弱的绿光发射(510~530 nm),Cu的掺杂使ZnO的绿光发射变为蓝光发射。蓝紫光的发射波长随煅烧温度的升高产生明显的红移,由300℃时的404 nm红移至600℃时的422nm,发射强度随温度升高先增大后减小。 相似文献
137.
Xinnan Wang Shuping Xu Haibo Li Jinlong Tao Bing Zhao Weiqing Xu 《Journal of Raman spectroscopy : JRS》2012,43(3):459-463
A three‐dimensional surface‐enhanced Raman scattering (SERS) substrate via the self‐assembly of properly sized Au nanoparticles in anodic aluminum oxide templates was designed and prepared. Au nanoparticles first underwent hydrophobic surface modification. Then, the hydrophobic Au nanoparticles self‐assembled, aggregated and formed many hot spots in the anodic aluminum oxide templates through a supramolecular interaction. We chose thiophenol as a probe molecule to evaluate the SERS enhancement ability of this three‐dimensional substrate. The enhancement factor was calculated to be 4.6 × 106 under the radiation of a 785‐nm laser. By further comparing SERS signals from different points on the same substrate, we confirmed that this substrate possessed good reproducibility and could be applied for SERS detection. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
138.
Accumulation-type GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) with atomic-layer-deposited Al2O3 gate dielectrics are fabricated. The device, with atomic-layer-deposited Al2O3 as the gate dielectric, presents a drain current of 260 mA/mm and a broad maximum transconductance of 34 mS/mm, which are better than those reported previously with Al2O3 as the gate dielectric. Furthermore, the device shows negligible current collapse in a wide range of bias voltages, owing to the effective passivation of the GaN surface by the Al2O3 film. The gate drain breakdown voltage is found to be about 59.5 V, and in addition the channel mobility of the n-GaN layer is about 380 cm2/Vs, which is consistent with the Hall result, and it is not degraded by atomic-layer-deposition Al2O3 growth and device fabrication. 相似文献
139.
In this paper, we investigated the electrochemical and surface behavior of hydroxyapatite (HA)/Ti films on the nanotubular Ti-35Nb-xZr alloy. The Ti-35Nb-xZr ternary alloys with 3-10 wt.% Zr content were made by an arc melting method. The nanotubular oxide layers were developed on the Ti-35Nb-xZr alloys by an anodic oxidation method in 1 M H3PO4 electrolyte containing 0.8 wt% NaF at room temperature. The HA/Ti composite films on the nanotubular oxide surfaces were deposited by a magnetron sputtering method. Their surface characteristics were analyzed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and an X-ray diffractometer (XRD). The corrosion behavior of the specimens was examined through potentiodynamic and AC impedance tests in 0.9% NaCl solution. From the results, the Ti-35Nb-xZr alloys showed a solely β phase microstructure that resulted from the addition of Zr. The nanotubular structure formed with a diameter of about 200 nm, and the HA/Ti thin film was deposited on the nanotubular structure. The HA/Ti thin film-coated nanotubular Ti-35Nb-xZr alloys showed good corrosion resistance in 0.9% NaCl solution. 相似文献
140.
F. de Moure-Flores J.G. Quiñones-GalvánA. Hernández-Hernández A. Guillén-CervantesM.A. Santana-Aranda M. de la L. OlveraM. Meléndez-Lira 《Applied Surface Science》2012,258(7):2459-2463
Transparent conducting SnO2:Cd thin films were prepared by RF reactive magnetron co-sputtering on glass slides at a substrate temperature of 500 °C using CdO as cadmium source. The films were deposited under a mixed argon/oxygen atmosphere. The structural, optical and electrical properties were analyzed as a function of the Cd amount in the target. The X-ray diffraction shows that polycrystalline films were grown with both the tetragonal and orthorhombic phases of SnO2. The obtained films have high transmittance and conductivity. The figure of merit of SnO2:Cd films are in the order of 10−3 Ω−1, which suggests that these films can be considered as candidates for transparent electrodes. 相似文献