【作者】 孙小飞；

【导师】 魏长平；

【作者基本信息】 长春理工大学 ， 材料物理与化学， 2009， 博士

【摘要】 将纳米尺寸的金属(尤其是Ag和Cu)粒子和氧化物镶嵌于无机介质(如玻璃、陶瓷等)中所形成的纳米复合材料具有不同于块体材料的光学特性,如光学非线性(包括等离子激元共振)、光吸收、光致发光等。由于具有这些性质,这类纳米复合材料在光开关、光波导器件、光滤波器和显示器件等方面有着非常广阔的应用前景。近年来,这类材料的制备及其性能的研究正成为材料科学和物理学领域的重要研究课题。采用溶胶-凝胶法和旋涂技术,通过紫外光辐照和热处理得到了不同Ag含量的均匀性良好的Ag／SiO2纳米复合薄膜,薄膜结构致密,基本没有孔洞。薄膜组织中的Ag纳米颗粒分布较均匀,尺寸都非常小。随着nAg／nsi的增加,Ag纳米粒子在420nm左右的紫外-可见吸收逐渐增强,并且出现一定的红移。在nAg／nsi=0.05、0.08的紫外辐照得到的薄膜样品中,分别在640nm和690nm左右存在一个宽吸收峰,是由于少量Ag颗粒较大所致。紫外辐照得到的薄膜样品的光吸收性能要优于300℃热处理1h得到的样品。Raman光谱表明,由于Ag纳米颗粒表面局域电磁场增强造成的表面增强拉曼散射,使得样品的峰强是衬底的5倍。利用紫外光辐照还原得到了均匀性良好的Au／SiO2复合薄膜,所得到的Au／SiO2复合薄膜中,纳米颗粒的尺寸比较小,分布均匀；复合薄膜的光吸收性能表明,Au纳米粒子的表面等离子共振吸收峰随着焙烧温度的增加以及nAu／nsi的改变,从585 nm附近逐渐红移至600 nm附近,并逐渐增强。根据Mie理论和Maxwell-Gamett有效介质理论,复合薄膜吸收峰的形状和位置由金粒子的介电常数和介质的介电常数所决定,薄膜的致密化,基质介电常数的增加,nAu／nsi越大,金纳米粒子越大,导致复合薄膜的吸收带红移。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照得到了不同nAg／nAu(1：0,2：1,1：2,0：1)的Ag-Au合金／SiO2复合薄膜。从SEM、XRD等表征手段的结果中可以看出所得到的纳米复合薄膜中合金颗粒的尺寸为10 nm左右,所得到的薄膜均匀性好；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nAg／nAu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(SPR)峰430 nm附近,逐渐红移到金纳米粒子的等离子共振吸收峰605nm和880nm附近。从光吸收谱可以看出,nAg：nAu=2：1和1：2的两个样品分别在515 nm、730 nm附近和550 nm、730 nm附近处的表面等离子共振吸收峰表明了Au-Ag合金固溶体的形成。采用溶胶-凝胶法在玻璃衬底上制备了ZnO／SiO2复合薄膜,研究了温度对ZnO／SiO2复合薄膜的结构及光学性能的影响,考察了ZnO含量对薄膜光学性能的影响。测试结果表明,温度的升高有利于样品的结晶,并能减少结构缺陷,但同时也促使了薄膜内颗粒发生团聚。复合薄膜经400℃热处理后有较好的透过率,样品在蓝光区域有较强的发射峰。ZnO含量的增加能调节薄膜的光学带隙,并增强薄膜在紫外和蓝光区域的光致发光强度。考察了Ag掺杂量对复合薄膜的结构及光学性能的影响。结果表明,经300℃热处理后薄膜中有单质Ag生成,随着Ag含量的增加,Ag与ZnO之间的电子转移及Ag颗粒的变大促使Ag的特征吸收峰呈现红移和宽化。Ag掺入后代替Zn位和间隙位减少空穴浓度和结构缺陷,使得样品位于紫外区和可见光区的发光强度减弱。更多还原

【Abstract】 The study of the composite films of metal (especially Ag, Au and Cu) nanoparticles and dielectric matrices, are of considerable interest in the world of materials science because of their unique physical and chemical properties, including surface plasmon resonance, surface enhanced Raman, surface enhanced fluorescence, metal nanoshells, and semiconductor quantum dots. Such properties provide excellent potential applications in electronics and passive optical components. They are also useful for photonic and magnetic devices and decorative colored glass wares.Ag/SiO2 composite thin films were prepared by means of sol-gel method and deoxidized using UV radiation, and were characterized by XRD, SEM, IR, UV-Vis, PL and Raman spectroscopy. The results of XRD indicate that the sample exhibits a typical face-centered cubic (fcc) silver phase. The results of SEM show that the composite thin films are very homogeneous and the size of Ag nanoparticles is small. The thickness of the films is about 1μm. The results of the optical absorption spectra show that the intensity of the absorption peaks at 420 nm is increasing with the molar ratio of Ag/Si, and the absorption peaks have some red shift. The PL spectra show that the luminescent intensity at 442 nm is very strong and decreases a little with the increase of nAg/nsi. And some blue shift appears. The results of Raman spectra indicate that the surface enhanced Raman scatter aroused by the enhancing of the surface region electromagnetic field of Ag nanoparticles appears.Au/SiO2 composite thin films were prepared by means of sol-gel method and deoxidized using UV radiation, and were characterized by SEM, TEM, XRD and UV-Vis spectroscopy, et al. The results of XRD show that the Au nanoparticles dispersed in amorphous SiO2 exhibit a typical face-centered cubic (fcc) phase. The results of SEM indicate that the composite thin films are very homogeneous and the size of the nanoparticles is small. The results of the optical absorption spectra show that the intensity of the absorption peaks becomes stronger and has some red shift from 585 nm to 600 nm and with the increasing of the temperature and nAu/nSi. And the samples with larger nAu/nSi exhibit absorption at 820 nm,900 nm and 585 nm of near-infrared region.Ag-Au alloys/SiO2 composite thin films (nAg/nAu=1:0,2:1,1:2,0:1)were prepared with AgNO3, HAuCl4 and TEOS by means of sol-gel method and deoxidized using UV radiation. The results of SEM and XRD indicate that the composite thin films are very homogeneous and the size of the nanoparticles is about 10 nm. The results of the optical absorption spectra show that the absorption peaks have some red shift from 430 nm belonged to the SPR absorption peak of Ag nanoparticles to 605 nm and 880 nm belonged to the SPR absorption peaks of Au nanoparticles with the increasing of nAg/nAu.The SPR absorption peaks around 515 nm,730 nm and 550 nm,730 nm belonged to the samples (nAg:nAu=2:1,1:2), respectively, show the formation of Ag-Au Alloys dispersed in the SiO2Structure and photoluminescent properties of the ZnO/SiO2 composite thin films under the influence of different calcined temperature were studied, and the photoluminescent properties of ZnO/SiO2 composite film with different concentration of ZnO were studied too. The result shows that high calcined temperature is good for the crystallization of samples and the reducing of structural defects. The particles become larger as the calcined temperature rise and partly reunion. The highest transmission composite film is calcined at 400℃. There are strong blue emission peaks of samples. The band gap changed and the emission peak intensity at ultraviolet and blue region increased with the concentration of ZnO increased. Ag-ZnO/SiO2 composite thin films with Ag doped in ZnO layer were prepared. And the structure and photoluminescent properties of composite thin films under the influence of different Ag concentration were also discussed. The result shows that there is diffraction peak of Ag after annealed in air at 300℃as the content of Ag increased, the absorption peaks have red shift and widen because of the electron transfer between Ag and ZnO and the particle size of Ag becoming larger. The photoluminescent intensity of the films in the section of ultraviolet and visible region weakened with the content of Ag increased, and this is owing to the reduction of the hole concentration and the compensation of structural defects caused by the doping of Ag.更多还原