Cu,Zn离子注入SiO_2纳米颗粒合成及氧气氛围下的热稳定性研究

通过45 keV,1.0×1017cm-2的Cu离子注入SiO2基底合成了嵌入式的Cu纳米颗粒,采用不同剂量的50 keV Zn离子对Cu纳米颗粒进行后续辐照,详细研究了Zn离子后续辐照对Cu纳米颗粒结构、光学性质的影响及其氧气气氛下的热演变规律.研究结果表明,Cu和0.5×1017cm-2的Zn离子顺次注入可在SiO2基底中形成Cu-Zn合金纳米颗粒,它们可以在516 nm附近引起独特的表面等离子共振(SPR)吸收峰.后续O2气氛中450?C退火可以导致Cu-Zn合金纳米颗粒分解,并在基体中形成了ZnO和Cu纳米颗粒.研究结果还表明后续Zn离子的辐照可以有效地提高Cu纳米颗粒的抗氧化能力;同时基体中Cu的存在也会加速Zn向样品表面的扩散,从而促进了ZnO的形成.     

Al2O3薄膜/纳米Ag颗粒复合结构的光吸收谱及增强Raman散射光谱研究

Al₂O₃介质薄膜与纳米Ag颗粒构成的复合结构,被应用于表面增强Raman散射探测实验中,其中Al₂O₃介质薄膜对纳米Ag颗粒的吸收谱及增强Raman散射光谱的影响被特别关注.该复合结构的光学特性表征出纳米Ag颗粒的偶极振荡特性.从光吸收谱中可以看到,其共振吸收谱随Al₂O₃介质薄膜厚度增加而在整个谱域上发生红移,表明纳米Ag颗粒的周围介电常数随Al₂O₃介质薄膜厚度的增加而增大.采用罗丹明6G作为探针原子,6个Raman特征峰的平均增益值作为表征表面增强Raman散射衬底增益程度的量度.实验结果表明,Al₂O₃介质薄膜层的引入提高了纳米Ag颗粒的衬底介电常数,并引起了散射共振的增强,从而使表面增强Raman散射强度提高. 关键词： 纳米Ag薄膜 共振吸收 表面增强Raman散射 介电常数     

SnO$lt;sub$gt;2$lt;/sub$gt;纳米晶体的制备、结构与发光性质

使用软化学方法在碱性溶液中制备出了颗粒尺寸分布均匀的SnO₂纳米颗粒,使用透射电子显微镜（TEM）、X射线衍射（XRD）、光致发光谱（PL）和光吸收谱等方法分析与表征了SnO₂纳米颗粒的结构和光学性能.实验中通过表面活性剂的加入来控制纳米颗粒的结晶与凝聚.XRD,TEM的结果表明,原始制备出的SnO₂纳米颗粒的平均粒径小于4 nm,为完好的晶体状态.纳米颗粒经过400—1000 ℃退火后晶粒尺寸进一步增大.光吸收谱表明,相对于体材料,纳米颗粒的禁带宽度展宽并随颗粒尺寸增大而红移.光致发光谱测试表明,不同温度下退火的SnO₂纳米颗粒在350—750 nm有较强的发光,研究表明这是来源于颗粒表面的氧空位缺陷发光. 关键词： 氧化锡 表面活性剂 纳米颗粒 光致发光     

[(Fe/Pt/Fe)/Ag]n多层膜低温合成分离的L10相FePt纳米颗粒

制备了［（Fe/Pt/Fe）/Ag］n多层膜,研究了不同温度退火后的微结构和磁特性.实验结果表明温度高于400℃退火后,样品开始形成L10相的FePt纳米颗粒与Ag基体的复合结构.ΔM曲线的测量表明FePt颗粒之间不存在交换作用,非常清楚地说明非磁基体Ag有效地隔离了FePt磁性颗粒.有序相的低温合成可能和多层膜结构所造成的界面扩散以及Ag层引入的界面缺陷有关,同时,Ag原子较强的迁移性以及FePt与Ag之间表面自由能的显著差异,使FePt纳米颗粒被Ag隔离. 关键词： L10相 FePt 交换作用     

纳米CdS-磺化聚苯胺（SPAn）多层复合膜的光学特性研究

研究了利用层-层自组织生长法制备的磺化聚苯胺-CdS纳米晶体复合膜的光学特性.研究发现，随样品中CdS 纳米晶体尺寸的减小，量子尺寸效应明显增强；在紫外吸收谱中表现为吸收边出现了明显蓝移；在光致发光谱中，不仅激子直接复合产生的带边发射产生了蓝移，而且陷阱态复合产生的宽带发射也发生了蓝移.还发现样品经低温退火处理后，激子复合产生的带边发射显著增强，发射带宽随纳米尺寸的减小而变窄.这说明退火后CdS 纳米晶粒的有序性和均匀度显著增加. 关键词： CdS 纳米晶体 SPAn 吸收 发光     

Ag离子注入非晶SiO2的光学吸收、拉曼谱和透射电镜研究

能量为200keV的Ag离子，以1×10¹⁶，5×10¹⁶，1×10¹⁷ cm^-2的剂量分别注入到非晶SiO₂玻璃，光学吸收谱显示：注入剂量为1×10¹⁶ cm^-2的样品的光吸收谱为洛伦兹曲线，与Mie理论模拟的曲线形状一致；注入剂量较大的5×10¹⁶，1×10¹⁷ cm^-2的谱线共振吸收增强，峰位红移并出现伴峰. 透射电镜观察分析表明，注入剂量不同的样品中形成的纳米颗粒的大小、形状、分布都不同，注入剂量较大的还会产生明显的表面溅射效应，这些因素都会影响共振吸收的峰形、峰位和峰强. 当注入剂量达到1×10¹⁷ cm^-2时，Ag纳米颗粒内部可能还形成了杂质团簇. 关键词： 离子注入 纳米颗粒 共振吸收 红移     

石墨烯/银纳米复合材料的制备及其影响因素研究

以硝酸银、鳞片石墨为原料, 在强碱环境下, 制备得到石墨烯/银纳米复合材料, 采用X射线衍射、红外吸收光谱、透射电子显微镜、紫外可见分光光度计对所制备的石墨 烯/银纳米复合材料进行了表征.结果表明: 氧化石墨烯和银离子在强碱NaOH的作用下, 氧化石墨烯失去部分含氧官能团, 被部分还原为石墨烯(rGO), 银离子被还原为纳米银颗粒, 均匀分布在氧化石墨烯片层表面, 颗粒大小和分布受硝酸银用量、反应温度、NaOH的加入顺序及前驱物混合方式等因素影响, 在GO与Ag粒子质量比为 1:1.08时, 负载在石墨烯片层上的银纳米颗粒集中在12 nm左右. 关键词： 石墨烯/银纳米复合材料 强碱溶液     

真空热退火温度对单相Ag2O薄膜微结构和光学性质的影响

利用直流磁控反应溅射技术在玻璃衬底上沉积了单相Ag₂O薄膜,并采用真空热退火对单相Ag₂O薄膜在不同热退火温度 (T _{A) 下进行了1 h热处理.利用X射线衍射谱、扫描电子显微镜和分光光度计研究了 T A对单相Ag2O薄膜微结构和光学性质的影响.研究结果表明, T}A= 300 ℃ 时Ag₂O薄膜中开始出现Ag纳米颗粒,且随着 T _{A的升高薄膜中Ag的含量 关键词： 2}O薄膜')" href="#">Ag₂O薄膜 热退火温度 微结构 光学性质     

InP/SiO2纳米复合膜的微观结构和光学性质

应用射频磁控共溅射方法在石英玻璃和抛光硅片上制备了InP/SiO₂复合薄膜,并在几种条件下对这些薄膜进行退火.X射线光电子能谱和卢瑟福背散射实验结果表明,复合薄膜中InP和SiO₂的化学组分都大体上符合化学计量配比.X射线衍射和激光喇曼谱实验结果都证实了复合薄膜中形成了InP纳米晶粒.磷气氛保护下的高温(520℃)退火可以消除复合薄膜中残存的In和In₂O₃并得到了纯InP/SiO₂纳米复合薄膜.实验观察到了室温下纳米复合薄膜的明显的光学吸收边蓝移现象和光学非线性的极大增强 关键词： InP 纳米晶粒 微观结构 光学性质     

射频磁控共溅射GaAs/SiO2纳米颗粒镶嵌薄膜的光学性质

应用射频磁控共溅射方法和真空退火方法制备了GaAsSiO2纳米颗粒镶嵌薄膜.X射线衍射实验结果表明,经高温退火的薄膜中形成了面心立方闪锌矿结构的GaAs纳米晶粒,晶粒平均直径为1.5—3.2nm.吸收光谱展示了由于强量子限域引起的1.5—2eV的吸收边蓝移.室温光致荧光(PL)光谱显示了电子重空穴激子与电子劈裂空穴激子的近紫外和紫外双PL谱峰以及深俘获态的PL谱峰.对实验吸收边蓝移量与有效质量模型的蓝移量的悬殊差别、俘获态PL谱的形成以及PL谱线的特征作了解释.应用激光Z扫描技术测量了退火温度为500℃的复合膜在非共振条件下的光学非线性,结果表明,复合膜的非线性折射率系数和非线性吸收系数都比块材GaAs相应的系数增大了5个数量级.光学非线性系数增大主要起因于强量子限域效应 关键词： 射频磁控共溅射 GaAsSiO2纳米颗粒镶嵌薄膜 光谱 激光Z扫描     

Interface influence on the surface plasmon resonance of Ag nanocluster composite

Ag nanoclusters embedded in silica matrix were formed by ion implantation to different doses. The intensity of surface plasmon resonance absorption enhances with the increasing of the implanted dose, but decreases at dose higher than 1×10¹⁷ ions/cm² due to the surface sputtering effect. The lattice distortion of nanoclusters has been observed using a high-resolution transmission electron microscope. The positions of the resonance peaks are red-shifted after the samples were annealed in oxidizing atmosphere at elevated temperatures. The red shift is mainly attributed to the interactions of Ag nanoclusters with diffused oxygen and nanovoids.     

Effects of rapid quenching on the structural and magnetic properties of the Heusler alloy Cu2MnSn

The Heusler alloy Cu₂MnSn has been prepared by two methods; (1) the conventional method of annealing for an extended period of time just below the melting temperature, followed by quenching into ice water, and (2) rapid quenching from the melt onto the surface of a rotating Cu disc. X-ray diffraction and ¹¹⁹Sn Mössbauer effect measurements show that the annealed sample contains a significant quantity of a non-magnetic impurity phase while the rapidly quenched sample is essentially free from non-Heusler phases.     

Fabrication and evolution of Cu nanoparticles in Al2O3 crystal by ion implantation and annealing at different atmospheres

Single crystal Al₂O₃ samples were implanted with 45 keV Cu ion implantation at a dose of 1 × 10¹⁷ ions/cm², and then subjected to furnace annealing in vacuum or with a flow of oxygen gas. Various techniques, such as ultraviolet-visible spectroscopy, X-ray diffraction spectroscopy and atomic force microscopy, have been used to investigate formation of Cu NPs and their evolution. Our results clearly show that the evolution of Cu NPs depends strongly on annealing atmosphere in the temperature range up to 600 °C. Annealing in vacuum only gives rise to a slight change in the size of Cu NPs. No evidence for oxidization of Cu NPs has been revealed. Remarkable modifications in Cu NPs, including the size increase and the effective transformation into CuO NPs, have been observed for the samples annealed at oxygen atmosphere. The results have been tentatively discussed in combination with the role of oxygen from atmosphere in diffusion of Cu atoms towards the surface and its interactions with Cu NPs during annealing.     

Plasmonics: influence of the intermediate (or stick) layer on the efficiency of sensors

This paper reports the formation of Ge nanoclusters in a multi-layer structure consisting of alternating thin films of Ge-doped silica glass and SiGe, deposited by plasma-enhanced chemical vapor deposition (PECVD) and post annealed at 1100 °C in N₂ atmosphere. We studied the annealed samples by transmission electron microscopy (TEM) and Raman spectroscopy. As-deposited and annealed samples were analyzed by secondary ion mass spectroscopy (SIMS). TEM investigation shows that Ge nanoclusters were formed in the as-deposited SiGe layer and the SiGe layer was transformed into a silicon dioxide layer embedded with Ge nanoclusters after annealing. These nanoclusters are crystalline and varied in size. There were no clusters in the Ge-doped glass layer. Raman spectra verified the existence of crystalline Ge clusters. The positional shift of the Ge vibrational peak with the change of the focus depth indicates that the distribution of the stress applied to the Ge clusters varies with depth. SIMS measurements show clearly the dramatic O increase in the as-deposited SiGe layer after annealing. The creation of Ge nanoclusters by the combination of PECVD and annealing makes possible the application in complicated waveguide components. PACS 81.07.Bc; 78.66.Jg; 42.65.Wi     

Chemical- or radiation-assisted selective dealloying in bimetallic nanoclusters

A selective dealloying in bimetallic nanoclusters prepared by ion implantation has been found upon thermal annealing in oxidizing atmosphere or irradiation with light ions. In the first process, the incoming oxygen interacts preferentially with copper promoting Cu2O formation, therefore extracting copper from the alloy. In the second process the irradiation with Ne ions promotes a preferential extraction of Au from the alloy, resulting in the formation of Au-enriched "satellite" nanoparticles around the original AuxCu1-x cluster.     

Effects of annealing conditions on the electrical properties of Bi4-xNdxTi3O12 (x = 0.46) thin films processed at low temperature

Neodymium-substituted Bi₄Ti₃O₁₂ (BNdT) thin films were prepared by a chemical solution deposition technique on platinum- coated silicon substrates. All of the samples were annealed at the relatively low temperature of 600 °C by a rapid thermal annealing process in different atmospheres, such as O₂, air, and nitrogen, and vacuum. Irrespective of different annealing atmospheres, all of the BNdT thin films exhibit good ferroelectric properties, such as a saturated hysteresis loop, good fatigue endurance, and low leakage current density. A large remanent polarization (P_r) of ∼48 μC/cm² with an electric field of 240 kV/cm was observed from the BNdT thin film annealed in O₂ atmosphere. The BNdT thin films annealed in nitrogen and vacuum, at reduced oxygen partial pressures, exhibit smaller P_r than that annealed in oxygen. The difference of P_r of the BNdT thin films annealed in different atmospheres may originate from differences in the grain sizes and the number of oxygen vacancies. PACS 77.55.+f; 77.80.-e; 77.80.Fm; 81.15.-z     

Optical and structural properties of Ge-ion-implanted fused silica after annealing in different ambient conditions

Ge+ ions are implanted into fused silica glass at room temperature and a fluence of 1×10 17 cm-2 . The as-implanted samples are annealed in O2, N2 and Ar atmospheres separately. Ge0 , GeO and GeO2 coexist in the as-implanted and annealed samples. Annealing in different atmospheres at 600℃ leads each composite to change its content. After annealing at 1000℃, there remains some amount of Ge 0 in the substrates. However, the content of Ge decreases due to out-diffusion. After annealing in N2 , Si–N composite is formed. The absorption peak of GeO appears at 240 nm after annealing in O2 atmosphere, and a new absorption peak occurs at 418 nm after annealing in N2 atmosphere, which is attributed to the Si–N composite. There is no absorption peak appearing after annealing in Ar atmosphere. Transmission electron microscopic images confirm the formation of Ge nanoparticles in the as-implanted sample and GeO 2 nanoparticles in the annealed sample. In the present study, the GeO content and the GeO2 content depend on annealing temperature and atmosphere. Three photoluminescence emission band peaks at 290, 385 and 415 nm appear after ion implantation and they become strong with the increase of annealing temperature below 700℃, and their photoluminescences recover to the values of as-grown samples after annealing at 700℃. Optical absorption and photoluminescence depend on the annealing temperature and atmosphere.     

聚合物P3HT在不同退火温度下的空穴传输特性

运用交流阻抗方法系统研究了单空穴注入型器件ITO/PEDOT/P3HT/Ag（P3HT：poly（3-hexylthiophene））在多种退火温度下的电容-频率变化关系,推算出样品中相应条件下的空穴迁移率,发现退火温度对空穴迁移率有明显影响,未经过退火的样品空穴迁移率为10^-4cm²/Vs数量级,迁移率数值基本不随电场强度的改变而变化,退火后样品的空穴迁移率有明显提高,约为10^-3cm²/Vs数量级,此时,空穴迁移率 关键词： 空穴迁移率 聚合物 电容-频率特性     

Ion implantation inducing nanovoids characterized by TEM and STEM

The evolution of nanoparticles in sequentially ion-implanted Ag and Ag/Cu into silica glasses has been studied. The doses for implantation (×10¹⁶ ions/cm²) were 5Ag, 5Ag/5Cu and 5Ag/15Cu. Ag nanoclusters have been formed in the implanted 5Ag specimen. In the implanted 5Ag/5Cu specimen, some formed nanoclusters have brighter center features. With an increase of Cu ions dose, the nanoclusters with brighter center features become prevalent. The microstructural properties of the nanoparticles are characterized by transmission electron microscopy. Scanning transmission electron microscope high-angle annular dark field and high-resolution transmission electron microscopy are also utilized to study the formed nanoparticles. The results show that nanovoids have been induced into metal nanoparticles during the ion implanting process, not the core-shell nanoparticles as other workers believed. The nanovoids can be the aggregation of vacancies induced by irradiation.     

Study of local environment of Cu atoms in Fe73.5Cu1Nb3Si13.5B9 alloy with different annealing temperature

The local environment of Cu atoms in Fe73.5Cu1Nb3Si13.5B9 alloy was investigated by extended X-ray absorption fine structure(EXAFS).Cu clusters began to order when the annealing temperature was around 733 K from the results of the Fourier transform curves.The fitting results showed that the first shell of the near fcc(face-centered cubic)Cu clusters only contained Cu atoms.The coordination number increased with the annealing temperature.Subsequently,the occupancy rate increased from 33.3%(annealed at 733 K)to 100% (annealed at 853 K).This local structural change of Cu atoms could probably affect the distribution of the bcc(body-centered cubic)α-Fe in Fe73.5Cu1Nb3Si13.5B9 alloy.