Ag-Au合金/SiO$lt;sub$gt;2$lt;/sub$gt;复合薄膜的制备与表征

以AgNO₃,HAuCl₄和正硅酸乙酯为主要原料,利用溶胶-凝胶法和旋涂技术,通过热处理和紫外光辐射还原得到了不同n_Ag/n_Au（1∶0,2∶1,1∶2,0∶1）的Ag-Au合金/SiO₂复合薄膜.从扫描电子显微镜和X射线衍射谱的结果可以看出得到的薄膜均匀性好,复合薄膜中合金颗粒的尺寸为10 nm左右.利用紫外-可见分光光谱仪研究了复合薄膜的光吸收性能,结果表明,随着n_Ag/n_Au的降低,吸收峰的位置也由最初的Ag纳米粒子的等离子共振吸收峰430 nm附近,逐渐红移到Au纳米粒子的等离子共振吸收峰605和880 nm附近.从光吸收谱可以看出,n_Ag∶n_Au＝2∶1和1∶2的两个样品分别在515,730 nm附近和550,730 nm附近出现表面等离子共振吸收峰.这表明Au-Ag合金固溶体的形成. 关键词： 2')" href="#">Ag-Au合金/SiO₂ 紫外辐射 光吸收性能     

溶胶-凝胶制备ZnO-SiO2复合膜的量子效应和上转换发光

采用溶胶-凝胶技术在玻璃衬底上制备了ZnO薄膜和ZnO-SiO₂复合膜.原子力显微镜照片显示ZnO薄膜具有球状纳米晶粒;可见光-紫外透射光谱表明ZnO-SiO₂复合膜在可见光区的透过率大约是85%,透过率从330 nm开始下降,到290 nm附近降为零.由于量子效应,吸收边出现明显的蓝移.在室温下用不同波长的光激发ZnO-SiO₂复合膜,光致发光谱显示ZnO-SiO₂复合膜对应于激子发射的290 nm附近的紫外发光峰与透射谱所显示的吸收边位置一致,没有出现斯托克斯红移.同时,ZnO-SiO₂复合膜出现了双光子和三光子吸收现象和上转换发光现象. 关键词： 2')" href="#">ZnO-SiO₂ 量子效应 双光子和三光子吸收 上转换发光     

Synthesis and microstructure of metal oxide thin films containing metal nanoparticles by liquid phase deposition (LPD) method

Au nanoparticles dispersed SiO₂-TiO₂ composite films have been prepared by a novel wet process, Liquid Phase Deposition (LPD) method. The composite films were characterized by XRD, XPS, TEM, ICP, SEM and UV-VIS absorption spectroscopy. The results showed that the SiO₂-TiO₂ composite films containing Au^III and Au^I ionic species were co-deposited from a mixed solution of ammonium silicofluoride, ammonium hexafluorotitanate, boric acid and tetrachloroauric acid. The heat treatment induced the reduction of Au ions and formation of Au nanoparticles in the film. TEM observation revealed that the Au nanoparticles with 5-10 nm in diameter were found to be dispersed uniformly in the SiO₂-TiO₂ matrix. The optical absorption band due to the surface plasmon resonance of dispersed Au particles were observed at the wavelength of 550 nm and shifted toward longer wavelength with increasing heat treatment temperature. Received 28 November 2000     

Interaction between localized and propagating surface plasmons: Ag fine particles on Al surface

Samples consisting of Ag fine particles 4nm in size placed near to an Al surface were prepared by depositing Ag-SiO₂ composite films by a rf cosputtering method onto vacuum-evaporated Al films. Angle-scan attenuated total reflection (ATR) measurements were performed over a wide wavelength range (λ=350-630nm) covering the resonance region (λ-410nm) of localized surface plasmon (LSP) in the Ag particles. It was found that the existence of Ag fine particles near to the Al surface led to a deformation of the dispersion curve of the surface plasmon polariton (SPP) propagating on the Al surface, in particular, in the LSP resonance region. The interaction between LSP and SPP was found to become much stronger as the distance between the particles and the surface decreases. The theoretical calculations based on the effective medium theory, which gave an effective dielectric function of the Ag-SiO₂ composite film, reproduced the deformation of the dispersion curve of the SPP. The deformation of the dispersion observed experimentally was qualitatively explained by the behavior of the effective dielectric function of the Ag-SiO₂ composite film.     

Ag-SiO2复合薄膜形貌和吸收特性的研究

通过分层镀膜的方式制备Ag和SiO₂的分层结构，经过快速热退火后，Ag颗粒扩散到复合薄膜的表面附近. 通过改变Ag颗粒扩散的距离(SiO₂的膜厚)，可很好地控制Ag颗粒在复合薄膜表面附近的大小，浓度和形貌，进而对共振吸收特性产生影响. 在实验中，根据Ag颗粒扩散的长度来调节退火的时间. 发现经过足够长的时间(17.5min)后，Ag颗粒会形成平行于衬底的平面团簇. 由于Ag原子在平面团簇之间容易扩散，使得Ag颗粒的粒径平均值变小并趋于某一特定的半径，且粒径分布范围变小，导致吸收谱发生蓝移，吸收带变窄，且强度增加. 关键词： 复合薄膜 共振吸收 平面团簇     

纳米Ag颗粒复合薄膜的制备及其吸收特性

利用磁控溅射分层制备Ag和SiO₂薄膜,通过快速热处理,使Ag颗粒富集在复合薄膜的表面.研究了Ag膜层厚度、退火时间、退火温度和退火方式对Ag颗粒形貌的影响,以及Ag颗粒致密度对其共振吸收的影响.结果表明:通过控制每层Ag膜的厚度,可有效控制Ag颗粒形貌.当每层金属为2 nm、退火温度为500 ℃时,形成的颗粒粒径大小均匀且致密度较高.通过间断退火可有效降低Ag颗粒的粒径.发现Ag颗粒表面等离子共振吸收并没有随颗粒粒径的减小而明显降低,甚至提高.这和以往的报道不同.通过深入研究金属颗粒表面等离子体产生机理,发现其表面等离子共振吸收增强的原因是致密度较高的颗粒表面能级与费米能级差值较大,Ag颗粒内部的电子向颗粒表面迁移越多,形成新的费米能级E'_F的电子数就越多,表面等离子共振吸收就越强.最终得出了金属颗粒共振吸收不单纯依赖于金属粒径、和颗粒的致密度也有很大关系的结论.     

The film thickness dependent thermal stability of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>:Ag thin films as high-temperature solar selective absorbers

The monolayer Al₂O₃:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing at 700 °C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration, and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles. On the base of film thickness results, the multilayer Al₂O₃:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 °C for 70 h in air. It can be concluded that film thickness is an important factor to control the thermal stability of Al₂O₃:Ag thin films as high-temperature solar selective absorbers.     

掺Ag纳米颗粒的BaTiO3复合薄膜的非线性光学特性

通过准分子激光(XeCl, 308 nm, 20 ns)在MgO(100)单晶衬底上制备了不同掺杂浓度的Ag:BaTiO₃纳米复合薄膜,通过X射线衍射和X射线光电子能谱对薄膜的结构和组分进行了表征.在430 nm和470 nm附近观测到了不同浓度Ag纳米颗粒引起的等离子体吸收峰,通过z扫描技术对复合薄膜的三阶非线性光学特性进行了测量,并对其光学非线性的增强机制进行了讨论. 关键词： 金属纳米复合薄膜 激光沉积 非线性光学     

Absorption and photoluminescence properties of silver clusters in SiO<Subscript>2</Subscript> matrix

Absorption and luminescence properties of silver nanoclusters embedded in SiO₂ matrixes were studied experimentally. Thin SiO₂ films with different amount of silver were produced by co-deposition of Ag and SiO₂ onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350–450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties.     

Optical properties of sol-gel fabricated Mn/SiO2 nanocomposites: Observation of surface plasmon resonance in Mn nanoparticles

Manganese nanoparticles were grown in silica glass and silica film on silicon substrate by annealing of the sol-gel prepared porous silicate matrices doped with manganese nitrate. Annealing of doped porous silicate matrices was performed at various conditions that allowed to obtain the nanocomposite glasses with various content of metallic Mn. TEM of Mn/SiO₂ glass indicates the bimodal size distribution of Mn nanoparticles with mean sizes of 10.5 nm and 21 nm. The absorption and photoluminescence spectra of Mn/SiO₂ glasses were measured. In the absorption spectra at 300 nm (4.13 eV) we observed the band attributed to the surface plasmon resonance in Mn nanoparticles. The spectra proved the creation of Mn²⁺ and Mn³⁺ ions in silica glass as well. The absorption spectra of Mn/SiO₂ glasses annealed in air prove the creation of manganese oxide Mn₂O₃. The measured reflection spectra of Mn/SiO₂ film manifest at 240-310 nm the peculiarity attributed to surface plasmons in Mn nanoparticles.     

Au/SiO2纳米复合薄膜的微结构及光吸收特性研究

用多靶磁控溅射技术制备了Au/SiO₂纳米多层薄膜.利用透射电子显微镜以及吸 收光谱对Au/SiO₂复合薄膜的微观结构、表面形貌及光学性能进行了表征和测试 .研究结果表明：单层Au/SiO₂薄膜中Au沉积时间小于10s时，分散在SiO_{2< /sub>中的Au颗粒随Au的沉积时间的延长而增大；当沉积时间超过10s后，Au颗粒的尺寸几乎 不随沉积时间变化，但Au颗粒的形状由网络状结构变为薄膜状结构.［Au(t1关键词： 尺寸效应 纳米复合薄膜 吸收光谱 有效媒质理论}     

Ag:Bi2O3复合膜的线性和非线性光学性质

从实验和理论两个方面，探讨了金属Ag不同掺杂浓度对Ag:Bi₂O₃复合膜线性和非线性光学性质的影响. 用吸收光谱研究了Ag浓度与Ag:Bi₂O₃复合膜表面等离子体共振带之间的关系；用皮秒Z-扫描技术研究了共振和非共振情况下(激发光波长分别为532nm和1064nm)，金属Ag浓度与复合膜三阶非线性极化率的关系. 基于表面等离子体共振理论和局域场增强理论对复合膜进行了分析，得到了不同Ag浓度时Ag:Bi₂O₃复合膜的三阶非线性效应，研究了激发波长和金属浓度对复合膜线性和非线性光学性质的影响. 结果表明，等离子体共振增强和合适的金属掺杂浓度使得三阶极化率增强二个量级，在Ag浓度为35％左右和接近等离子体共振频率(相应吸收带位于560nm—622nm)的532nm激发时，χ⁽³⁾具有最大值2.4×10^-9esu. 关键词： 金属纳米颗粒 复合膜 三阶非线性 表面等离子体共振     

脉冲激光沉积Ag:BaTiO3纳米复合薄膜及其光学特性

在MgO(100)基片上利用脉冲激光沉积技术制备了掺有Ag纳米颗粒的BaTiO₃复合薄膜.通过X射线衍射对薄膜的结构进行了表征,利用透射电子显微镜对Ag纳米颗粒的尺寸、形态进行了观测,X射线光电子能谱结果表明Ag呈金属态.在410—500nm范围内观测到了Ag纳米颗粒引起的等离子振荡峰,随着后处理温度和Ag颗粒浓度的增加,吸收峰发生红移,并出现了双峰现象. 关键词： 金属纳米复合薄膜 激光沉积 光吸收     

Electron beam-physical vapor deposition of SiC/SiO2 high emissivity thin film

When heated by high-energy electron beam (EB), SiC can decompose into C and Si vapor. Subsequently, Si vapor reacts with metal oxide thin film on substrate surface and formats dense SiO₂ thin film at high substrate temperature. By means of the two reactions, SiC/SiO₂ composite thin film was prepared on the pre-oxidized 316 stainless steel (SS) substrate by electron beam-physical vapor deposition (EB-PVD) only using β-SiC target at 1000 °C. The thin film was examined by energy dispersive spectroscopy (EDS), grazing incidence X-ray asymmetry diffraction (GIAXD), scanning electron microscopy (SEM), atomic force microscopy (AFM), backscattered electron image (BSE), electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Fourier transformed infra-red (FT-IR) spectroscopy. The analysis results show that the thin film is mainly composed of imperfect nano-crystalline phases of 3C-SiC and SiO₂, especially, SiO₂ phase is nearly amorphous. Moreover, the smooth and dense thin film surface consists of nano-sized particles, and the interface between SiC/SiO₂ composite thin film and SS substrate is perfect. At last, the emissivity of SS substrate is improved by the SiC/SiO₂ composite thin film.     

Enhanced nonlinear optical absorption of Au/SiO2 nano-composite thin films

Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications.Au/SiO 2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma sputtering.Au particles as perfect spheres with diameters between 10 nm and 30 nm are uniformly dispersed in the SiO 2 matrix.Optical absorption peaks due to the surface plasmon resonance of Au particles are observed.The absorption property is enhanced with the increase of Au content,showing a maximum value in the films with 37 vol% Au.The absorption curves of the Au/SiO 2 thin films with 3 vol% to 37 vol% Au accord well with the theoretical optical absorption spectra obtained from Mie resonance theory.Increasing Au content over 37 vol% results in the partial connection of Au particles,whereby the intensity of the absorption peak is weakened and ultimately replaced by the optical absorption of the bulk.The band gap decreases with Au content increasing from 3 vol% to 37 vol % but increases as Au content further increases.     

Synthesis of α‐Willemite Nanoparticles by Post‐calcination of Flame‐made Zinc Oxide/Silica Composites

Composite ZnO/SiO₂ nanoparticles were made by flame spray pyrolysis (FSP). Characteristics of the product powder and its crystallization behavior on post‐calcination were evaluated. Polyhedral aggregates of nano‐sized primary particles consisting of ZnO nano‐crystals 1–3 nm in size and amorphous SiO₂ were obtained by FSP. A short residence time in the flame can result in the co‐existence of the ZnO and SiO₂ clusters without substitution or reaction hindering each other's grain growth. There was almost no change in the XRD pattern by calcination at 600 °C for 2 h, suggesting a high thermal stability of the ZnO nano‐crystals in the composite particles. A pure α‐willemite phase was obtained at 900 °C. At this calcination temperature, d_C and d_BET of the powder were 63 and 44 nm, respectively. The nano‐composite structure of the FSP‐made particles can suppress crystalline growth of ZnO during calcination to maintain a high reactivity of ZnO with SiO₂, obtaining pure α‐willemite with high specific surface area at low calcination temperatures.     

rf reactive co-sputtered Au-Ag alloy nanoparticles in SiO2 thin films

We have studied formation of Au-Ag alloy nanoparticles in sputtered SiO₂ thin films. Silica thin films containing Au-Ag nanoparticles were deposited on quartz substrates using rf reactive magnetron co-sputtering technique. The films heat-treated in reducing Ar + H₂ atmosphere at different temperatures. They were analyzed by using UV-vis spectrophotometry, atomic force microscopy and X-ray photoelectron spectroscopy (XPS) methods for their optical, surface morphological as well as structural and chemical properties. The optical absorption of the Au-Ag alloy nanoparticles illustrated one plasmon resonance absorption peak located at 450 nm between the absorption bands of pure Au and Ag nanoparticles at 400 and 520 nm, respectively, for the thin films annealed at 800 °C. XPS results showed that the alloys were in metallic state, and they had a greater tendency to lose electrons as compared to their corresponding monometallic state. Using lateral force microscopy analysis, we have found that the alloy particles were uniformly distributed on the surface with grain size of about 20 nm.     

Effects of post-thermal annealing temperature on the optical and structural properties of gold particles on silicon suboxide films

In this work, silicon suboxide (SiO_x) thin films were deposited using a RF magnetron sputtering system. A thin layer of gold (Au) with a thickness of about 10 nm was sputtered onto the surface of the deposited SiO_x films prior to the thermal annealing process at 400 °C, 600 °C, 800 °C and 1000 °C. The optical and structural properties of the samples were studied using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and optical transmission and reflection spectroscopy. SEM analyses demonstrated that the samples annealed at different temperatures produced different Au particle sizes and shapes. SiO_x nanowires were found in the sample annealed at 1000 °C. Au particles induce the crystallinity of SiO_x thin films in the post-thermal annealing process at different temperatures. These annealed samples produced silicon nanocrystallites with sizes of less than 4 nm, and the Au nanocrystallite sizes were in the range of 7-23 nm. With increased annealing temperature, the bond angle of the Si-O bond increased and the optical energy gap of the thin films decreased. The appearance of broad surface plasmon resonance absorption peaks in the region of 590-740 nm was observed due to the inclusion of Au particles in the samples. The results show that the position and intensity of the surface plasmon resonance peaks can be greatly influenced by the size, shape and distribution of Au particles.     

溅射法制备Ag/Ag2O超微粒子的分析

用Ｘ射线衍射、Ｘ射线光电子能谱、透射电子显微镜和差示扫描量热法对溅射法制备的Ａｇ超微粒子的晶体学结构、表面组成、微粒形态和热力学性质进行了分析。结果表明，所制备的微粒为内部为Ａｇ、表面为Ａｇ₂Ｏ的两相微粒，以及单一的Ａｇ₂Ｏ微粒，粒径在１０ｎｍ以上的微粒没有确定的外形，粒径在１０ｎｍ以下的微粒为球形。微粒有不同于块体金属Ａｇ的异常热效应。到４０天时，沉积在碳膜上的Ａｇ，Ａｇ₂Ｏ两相微粒有一部份还原形成了单一的金属Ａｇ超微粒子。 关键词：     

On the fluorescence enhancement mechanism of Er3+ in germanate glass containing silver particles

The spectral properties of trivalent erbium ions(Er3+) are systematically studied in a melt-quenched germanate glass(60 GeO2-20PbO-10BaO-10K2O-0.1Ag2O) containing silver(Ag) particles.Thermal treatment of the material leads to the precipitation of Ag particles as observed by transmission electron microscopy and confirmed by absorption spectrum for the obvious surface plasmon resonance peak of Ag particles.The fluorescence from Er3+ in the 10-min-annealed sample with Ag particles is found to be 4.2 times enhanced compared with the unannealed sample excited by 488-nm Ar+ laser.A comparison is made between a spectral study performed on the unannealed Er3+-doped sample and the one annealed for 20 min.The data of absorption cross section and Judd-Ofelt intensity parameters show the agreement between the two samples no matter whether there are Ag particles,indicating that the introduction of Ag particles by post-heat treatment has no effect on the crystal field environment of Er3+ ions.The fluorescence enhancement is attributed to the surface plasmon oscillations of Ag particles in germanate glass.