Optical Properties and Microstructure of Silver-Copper Nanoparticles Synthesized by Pulsed Laser Deposition

Utilizing a pulsed laser deposition (PLD) method, silver-copper (Ag-Cu) nanoparticles have been synthesized by changing the surface area ratio of the target (S _R = S _Cu/(S _Ag + S _Cu)) from 0 to 30%. The peak absorption attributed to surface plasmon resonance (SPR) increased when increasing S _R up to 15%, above which it decreased. The peak shifts seem to be induced by the changes in the conductivity and morphology of the Ag-Cu nanoparticles. Additionally, the interplanar spacings of the Ag-Cu nanoparticles prepared at S _R = 15% corresponded to the Ag {111}, {200}, {220}, and Cu {111} planes. However, since the interplanar spacings attributed to the Cu {200} and {220} planes were not detected, the Ag-Cu nanoparticles were believed to possess a lattice constant (a) close not to the Cu phase (a = 3.615 Å) but to the Ag phase (a = 4.086 Å). Moreover, confirming the presence of Cu atoms in the nanoparticles using energy dispersive X-ray (EDX) spectra, Ag-Cu nanoparticles may be a solid solution in which Cu atoms partially replace Ag atoms in the fcc structure.     

Investigations on Structural,Optical and Multiferroic Properties of Bismuth Ferrite Nanoparticles Synthesized by Sonochemical Method

BiFeO₃ nanoparticles have been synthesized using a sonochemical method. The phase identification of the prepared sample was characterized by x–ray powder diffraction, which confirmed the rhombohedral structure. The diffused reflectance spectra showed bands in the ultraviolet and visible regions and the optical band gap was calculated using the Kulbeka–Munk function. The magnetization measurement revealed a ferromagnetic behavior at room temperature and this has been confirmed through an Arrott–Belov–Kouvel plot. The BiFeO₃ nanoparticles exhibit a ferroelectric nature at room temperature and the leakage current density was measured under the applied electric field of ±?30 kV/cm.     

自催化方式制备ZnO纳米线及光致发光特性

采用化学气相沉积法,不用催化剂,在Si(111)基片上制备了ZnO纳米线。扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在100nm左右。X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰。室温下光致发光谱(PL)中出现了389nm和357nm的紫外峰以及五个蓝光峰(450,468,474,481和491nm)。389nm峰为自由激子复合发射357nm峰是在LO声子的参与下,自由载流子碰撞形成自由激子过程的发光行为;468nm峰系电子从氧空位形成的浅施主能级向价带跃迁发光;450nm峰系电子从导带向锌空位形成的浅受主能级跃迁发光;474,481和491nm峰是声子伴线。     

掺铜ZnS纳米材料的制备及光学性质

介绍了在聚乙烯醇衬底中利用离子络合法制备未掺杂和掺铜的 ZnS纳米微粒.TEM图表明ZnS纳米微粒较均匀地分布在PVA衬底上,粒径在1～10nm,且具有类似体材料的立方结构.与未掺杂ZnS相比,掺铜ZnS的紫外-可见吸收光谱没有明显的变化;但PL光谱的发射峰却从450nm移到了480nm左右,这可能是由于ZnS的导带和ZnS禁带中铜的能级T2之间的跃迁造成的.     

掺铜ZnS纳米材料的制备及光学性质

介绍了在聚乙烯醇衬底中利用离子络合法制备未掺杂和掺铜的 ZnS纳米微粒.TEM图表明ZnS纳米微粒较均匀地分布在PVA衬底上,粒径在1～10nm,且具有类似体材料的立方结构.与未掺杂ZnS相比,掺铜ZnS的紫外-可见吸收光谱没有明显的变化;但PL光谱的发射峰却从450nm移到了480nm左右,这可能是由于ZnS的导带和ZnS禁带中铜的能级T2之间的跃迁造成的.     

Controlling the Optical Properties of Inorganic Nanoparticles

The sophistication with which we can now prepare and characterize inorganic nanoparticles has inspired new areas of research into the fundamental properties and applications of these fascinating nanoscale systems. In this article some of the recent ideas concerning control of their optical properties are examined and explained, focusing on semiconductor nanocrystals. It is known that the optical properties of nanocrystals can be size‐tunable, but it is less obvious how shape matters. To explain how size as well as shape matters, the electronic structure of nanocrystals is sketched in relatively simple terms, leading to an introduction to deeper concepts at the heart of spectroscopy such as the exciton fine structure. The exciton fine structure states, although obscured by inhomogeneous line broadening, dictate selection rules for optical excitation. These viewpoints are compared and contrasted to well‐established principles in molecular spectroscopy that provide inspiration as well as perspective. The control of optical poperties is founded on our ability to prepare good quality colloidal particles. Recent advances in nanocrystal shape control are described. The current status of heterostructures is examined, with an emphasis on charge separation in CdSe–CdTe nanorods.     

Linear and Nonlinear Optical Properties of Si Nanoparticles/ Er-Ions Doped Optical Fiber

An alumino-germano-silica glass fiber doped with silicon nanoparticles and erbium ions was fabricated using the modified chemical vapor deposition (MCVD) method. Optical properties of the glass fiber were investigated using a Judd-Ofelt analysis. It was found that incorporating silicon nanoparticles with erbium ions did not alter Er-related optical properties of the silica glass fiber. The incorporation of silicon particles in a fiber core caused wide band absorption from 480 nm to 1200 nm. A third order optical nonlinearity of the Si-Er-doped alumino-germano-silica glass fiber was measured to be about 3.8 x 10^-15 m²/W.     

ZnS纳米粒子的水热法和溶剂热法制备

选用醋酸锌和硫代硫酸钠为原料,在“活性”水或甲苯中进行氧化－还原反应,制备了质量良好的ZnS纳米粒子。主要探讨在高温和高压的条件下以水或甲苯作为反应介质对ZnS粒子结构和形貌的影响。通过XRD、TEM、DSC等测试手段对ZnS粒子进行了分析。结果表明,所制备的ZnS纳米粒子粒径很小（约20nm),晶粒单一,属于立方晶系,分散性较好,结晶度、纯度较高,活性大,具有良好的应用前景;密闭高压体系有助于纳米粒子的分散和结晶度,产率的提高;与以去离子水作为反应介质相比,甲苯作为反应介质合成的ZnS纳米粒子纯度更高,分散性更好,但成本相应提高,此外,它在乙醇中的稳定性比在去离子水中的稳定性要好,粒子极性相对较低。     

溅射法制备ZnO薄膜结构及光学特性

采用直流磁控溅射镀膜工艺在玻璃基片上沉积了具有良好c轴择优取向的znO薄膜.用组合式多功能光栅光谱仪测得透光率均在85%以上;用AXRF分析了退火前后薄膜的物相,并用原子力显微镜分析了薄膜的表面形貌.样品通过空气中退火,薄膜结晶质量明显提高,晶粒有所长大,取向更加一致.在室温下用荧光分光光度计分析了薄膜的发光特性,观测到明显的紫外光发射(波长为386 nm)和波峰为528nm的一"绿带"宽峰.紫外发射是由于导带和价带之间的电子跃迁,宽峰是源于晶体的缺陷.     

锐钛矿相TiO2电子结构和光学性质的第一性原理计算

采用第一性原理平面波超软赝势方法计算了锐钛矿相TiO2的电子结构和光学性质,并从理论上分析了它们之间的关系.利用精确计算的能带结构和态密度分析了电子带间跃迁占主导地位的锐钛矿相TiO2的介电函数、复折射率、反射率和吸收系数,理论计算得到的结果与实验测量结果基本一致.结果表明锐钛矿相TiO2在E//c和E上c两个极化方向上具有明显的光学各向异性,为锐钛矿相TiO2的应用提供了理论依据.     

锐钛矿相TiO2电子结构和光学性质的第一性原理计算

采用第一性原理平面波超软赝势方法计算了锐钛矿相TiO2的电子结构和光学性质,并从理论上分析了它们之间的关系.利用精确计算的能带结构和态密度分析了电子带间跃迁占主导地位的锐钛矿相TiO2的介电函数、复折射率、反射率和吸收系数,理论计算得到的结果与实验测量结果基本一致.结果表明锐钛矿相TiO2在E//c和E上c两个极化方向上具有明显的光学各向异性,为锐钛矿相TiO2的应用提供了理论依据.     

纳米光存储薄膜结构的光学性质

近场超分辨纳米薄膜结构可以突破衍射极限实现纳米尺寸信息存储,是下一代海量存储技术的重要方案之一,也是纳米光子学研究中的热点.纳米膜层结构基于激光作用下的非线性局域光学效应实现超分辨.分析了超分辨近场薄膜结构突破衍射极限的光学原理,对超分辨纳米薄膜结构的表面等离子体激发特性、非线性光学特性、近场光学特性和超透镜效应等重要光学性质的最新研究进展做了系统介绍.     

Synthesis of Monodisperse FeAu Nanoparticles with Tunable Magnetic and Optical Properties

Monodisperse FeAu nanoparticles can be synthesized via the reduction of gold acetate by 1,2‐hexadecanediol and the thermal decomposition of iron pentacarbonyl in the presence of the stabilizers oleic acid and oleylamine. The effects of composition, reaction time, and reaction temperature on their size, structure, and optical and magnetic properties are studied. It is found that the incorporation of Au into Fe nanoparticles leads to a structural change from body‐centered cubic (bcc) to face‐centered cubic (fcc). The size of the particles decreases with increasing reaction time and temperature because of atom rearrangement, and varies with the Au/Fe molar ratio as a result of the faster reduction rate of gold acetate compared with the decomposition rate of iron pentacarbonyl and the associated changes in nucleation and growth processes. The resultant FeAu nanoparticles possess the optical properties of Au nanoparticles and the magnetic properties of Fe nanoparticles. Their characteristic absorption bands, in the visible light range, become broader with decreasing Au/Fe molar ratio or increasing reaction time and temperature. Also, they are red‐shifted with decreasing the Au content and blue‐shifted with increasing reaction time. In addition, the particles are nearly superparamagnetic. With the increase in the Au/Fe molar ratio, their blocking temperature and coercivity increase while the saturation magnetization and remnant magnetization decrease. They can be self‐assembled into parallel stripes in the direction of an applied magnetic field.     

Study of the Structural,Optical, Dielectric and Magnetic Properties of Copper-Doped SnO2 Nanoparticles

Journal of Electronic Materials - This work explores the structural, optical and dielectric properties and the magnetic behaviour of copper (Cu) (0–4%)-doped tin dioxide (SnO2) nanoparticles,...     

Optical and structural properties of sol-gel derived nanostructured CeO2 film

Sol-gel derived nanostructured CeO2 film was deposited on glass substrate using by dip-coating technique with annealing at 65℃.X-ray diffraction (XRD),scanning electron microscopy (SEM),Fourier transform infrared (FTIR),UV/vis and photoluminescence (PL) spectroscopy studies were employed to analyze the structural and optical properties of the sol-gel derived nanostructured CeO2 film.The average crystallite size was estimated from the XRD pattern using by Scherrer equation as about 3-4nm.An SEM micrograph shows that the film was porous in nature and crack free.The UV-visible absorption spectroscopic measurement results showed that the products had conspicuous quantum size effects.The absorption spectrum indicates that the sol-gel derived nanostructured CeO2 film has a direct bandgap of 3.23 eV and the photoluminescence spectra of the film show a strong band at 378 nm:it may have a promising application as an optoelectronic material.     

Properties of Lead-Sulfide Nanoparticles in a Multicrystalline Structure

The structural and electrical properties of PbS nanoparticles (40–70 nm), produced by a chemical reaction of sodium hydroxide with lead nitrate and electrophoretically deposited onto a conductive substrate, are investigated. The composition and structure of the nanoparticles are identified by X-ray analysis as pure PbS phase with a face-centered cubic lattice. Several minima, related to plasma-resonance absorption at 10–17 μm, are observed in the frustrated total internal reflection (FTIR) spectra. The layer morphology and the nanoparticle shape and sizes are determined by scanning electron and tunneling microscopy. The threedimensional topograms show that the surface fine structure is a set of faceted pyramidal spikes with a size of 5–10 nm and a density of ~400 μm^–2. An analysis of the tunneling current–voltage characteristics of individual nanospikes shows the presence of low-field emission and makes it possible to determine the barrier heights (1.6–1.8 eV), which are explained within the quantum-dot (QD) model.