退火温度对多铁性YFeO_3薄膜的结构、光学及磁学性能的影响

采用溶胶-凝胶旋涂法在(111)掺钇氧化锆(YSZ)基片上制备了多铁性YFeO_3薄膜,并用X射线衍射仪、原子力显微镜、紫外-可见分光光度计及磁性测量系统,研究了退火温度对YFeO_3薄膜的微观结构、光学和磁学性能的影响。结果表明:YFeO_3薄膜具有正交钙钛矿的多晶结构,退火温度高于1123K时,薄膜产生了(002)、(311)面的择优取向生长;但当退火温度提高至1 223 K时,由于再结晶,薄膜晶粒尺寸及表面粗糙度显著增大;YFeO_3薄膜在可见光区具有明显的光响应性能,其带隙约为2.21~2.29eV;同时YFeO_3薄膜具有室温铁磁性,提高退火温度,样品磁化强度变大,而矫顽力减小。     

TiO2薄膜的相变与光学性能

采用射频磁控溅射法在单晶硅片和石英玻璃片上沉积TiO2薄膜.通过X射线衍射、原子力显微镜、X射线光电子能谱、紫外可见光谱和荧光发射光谱对薄膜的结构、相组成和表面形貌进行了表征.研究了退火温度对薄膜相结构、表面化学组成、形貌及光学性能的影响.结果表明:沉积的TiO2薄膜为无定形结构,经400℃以上退火后的薄膜出现锐钛矿相,600℃以上退火后的薄膜开始出现金红石相,1000℃以上退火的薄膜完全转变为金红石相.随着退火温度的升高,晶粒尺寸逐渐增大,仅在950～l000℃时出现减小,1 000℃退火的薄膜组成为TiOx.随着退火温度的升高,薄膜的透射率下降,折射率和消光系数有所增加.     

射频磁控溅射法制备PI基CeO2-TiO2复合薄膜

采用射频磁控溅射技术在柔性基体PI(聚酰亚胺)上制备了纳米CeO2-TiO2复合薄膜.借助X射线衍射(XRD)、原子力显微镜(AFM)和紫外-可见光谱仪分别研究了薄膜的物相结构、表面生长形貌和薄膜的紫外-可见光透过率及光学能隙,并用WS-2000型薄膜划痕仪测定薄膜与基体的界面结合强度.实验结果表明:沉积态的薄膜为非晶态,经200℃退火处理4h后,转化为良好的晶态,薄膜中主要含有锐钛矿相结构;溅射功率对薄膜的形貌,光学性能及界面结合力均有影响.尤其当溅射功率为120W时,薄膜的综合性能最优;平均晶粒尺寸110nm,表面粗糙度为160nm,吸光率达80%,光学能隙Eg仅为(2.65±0.05)eV,划痕法测量涂层与基体的附着力为60N.     

水热法制备In掺杂ZnO薄膜的表面形貌及其光学性质

采用水热法在ZnO籽晶层上制备了不同In掺杂量的ZnO薄膜,用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外可见分光光度计和荧光光谱仪等测试分析薄膜的微结构、表面形貌、透射谱和室温光致发光谱.结果表明,In离子的掺入未改变薄膜的晶相结构,但抑制了ZnO晶粒的生长,使得ZnO的结晶度明显下降.随着In含量的增加,薄膜表面rms粗糙度和平均颗粒尺寸均逐渐减小,光学带隙Eg先增大后减小.所有薄膜的PL谱中均观察到405 nm左右的紫光发光带,研究了In掺杂量对紫光发光带的强度和峰位的影响,并对其紫光发射机理进行了探讨.     

纳米TiO2-CeO2复合薄膜的结构和光学性能

采用射频磁控溅射法在柔性基体聚对苯二甲酸乙二醇酯上制备了纳米TiO2-CeO2复合薄膜.采用x射线衍射仪、扫描电镜和紫外-可见光谱仪研究了薄膜的物相结构、表面形貌和镀膜样品的紫外-可见光透过率及光学能隙.结果表明:沉积态的薄膜为非晶态,经150℃退火处理12h后,转化为良好的晶态,薄膜中主要含有锐钛矿结构TiO2,未出现CeO2的特征峰.随退火时间的延长及CeO2含量的增加,复合薄膜表面的球形晶粒数量增多,尺寸增大,且复合薄膜的透光率增加,禁带宽度减小.特别是当CeO2质量分数为10%,退火处理时间为12h时,晶粒尺寸为120nm,薄膜表面结晶最好;吸收边波长和截止波长均发生红移,分别从常温下的431,338 nm增加至554,351 um,禁带宽度仅为(2.62±0.05)eV,提高了薄膜对太阳光或可见光的利用率.     

不同退火温度对HfO_2薄膜结构和性能的影响

采用等离子增强蒸发镀膜方法在石英玻璃上制备了HfO_2薄膜,并进行了退火实验。利用X射线衍射(XRD)、纳米压入仪、紫外-可见分光光度计等分别研究了不同退火温度对HfO_2薄膜表面硬度、晶体结构和光学性能的影响。结果发现:未退火的HfO_2薄膜为非晶结构,退火之后,薄膜变为多晶结构,呈现出(002)晶面择优生长;随着退火温度的增加,膜层的表面硬度有明显提高;退火后,可见光波段和近红外波段透过率没有明显的变化。     

Na掺杂ZnO薄膜光诱导亲水性的转化(英文)

采用溶胶-凝胶技术在Si(111)和石英基片上制备8%(摩尔分数)Na掺杂ZnO薄膜。用X射线衍射仪、原子力显微镜、扫描电镜和接触角测试仪测试薄膜的微结构、表面形貌和表面接触角。结果表明:所有薄膜均具有较好的c轴择优取向,表面由近六边形棒状颗粒构成。随着退火温度升高,薄膜表面接触角由95°增大到106°。通过对薄膜交替进行紫外光照和黑暗放置(或热处理),可以实现其表面疏水与超亲水性之间的可逆转化,光诱导可逆转化效率随退火温度升高而增大。     

择优取向氮掺杂氧化铟薄膜的制备及其光电性能

为探索氧化铟基半导体薄膜择优取向的控制生长策略，并探究晶面取向对光电性能的影响，采用磁控溅射技术在石英(SiO2)衬底上分别制备了具有(222)和(440)晶面择优取向的氮掺杂氧化铟(In2O3:N)薄膜，利用X射线衍射仪、扫描电子显微镜、X射线光电子能谱仪、紫外–可见分光光度计对In2O3:N薄膜的晶体结构、表面形貌、元素组成、光学带隙进行了表征，并研究了不同择优取向薄膜的光电特性。结果表明：不同择优取向In2O3:N薄膜的氮掺杂均以替位式为主，氮掺杂会导致氧化铟的禁带宽度减小至2.89 eV。相比(222)晶面择优取向，(440)晶面择优取向的In2O3:N薄膜的光响应时间更短。     

La1-xCaxMnO3团簇薄膜的介电和光学性质研究

利用溶胶-凝胶法制备La1-xCaxMnO3薄膜.利用X射线衍射(XRD)、反射偏光显微镜和电感-电容-电阻测定计(LCR)仪对其结构、形貌和性质进行表征.XRD结果表明薄膜为钙钛矿结构,经不同温度退火后发生微小偏离.偏光显微图像显示薄膜表面形貌为菊花状团簇;经不同温度退火后的薄膜反射色有很大差异,因此反射色不能作为鉴定La1-xCaxMnO3的依据.随着退火温度升高,薄膜的介电损耗降低,说明高的温度退火后,薄膜质量较高.     

射频磁控溅射制备高In组分Al1-xInxN薄膜及其光学性能

采用射频磁控溅射法,在硅和石英衬底上生长了高In组分Al_(1-x)In_xN薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见-红外分光光度计分别对Al_(1-x)In_xN薄膜的结构、形貌和光学带隙进行表征,并在室温下测量Al_(1-x)In_xN薄膜的光致发光(PL)谱。结果表明:Al_(1-x)In_xN薄膜均呈(002)择优取向,具有单相纤锌矿结构,In组分为x=0.64-0.76。随着In组分升高,薄膜表面更加光滑,光学带隙值由1.93 eV红移至1.87 eV。In组分x=0.64,薄膜以本征发光为主,随着In组分增加,出现了附加的发光峰,这可归因于Moss-Burstein效应。     

锑掺杂量对ATO薄膜结构及光、电性能的影响

以四氯化锡和三氯化锑为主要原料,采用溶胶-凝胶法制备了不同锑掺杂量的纳米锑掺杂二氧化锡（ATO）薄膜。分别利用XRD、FESEM、紫外可见分光光度计和四探针电阻仪对晶体结构、薄膜形貌、光透过率和薄膜方块电阻进行表征,考察锑掺杂量对ATO薄膜晶体结构、晶粒尺寸、光透过率和导电性能的影响。结果表明：所制备的ATO薄膜为（110）面择优取向的四方相锡石结构,晶粒尺寸小于26 nm,当锑掺杂量为10%（物质的量分数）时,ATO薄膜具有最小的方块电阻（60.1 Ω/□）,可见光透过率大于85%。     

Magnetic and Photocatalytic Behaviors of Ba‐Doped BiFeO3 Nanofibers

BiFeO₃ nanofibers doped with divalent barium have been fabricated using electrospinning technique. Phase transition from space group R3c to C222 can be observed by the Ba doping. Our results indicate that these BiFeO₃ nanofibers show obvious room temperature ferromagnetic behaviors, which can be enhanced remarkably with the increment of Ba doping. Microstructure and composition analysis indicates that barium effectively affected the magnetism after doping content was more than 5% and optical properties.     

Effect of nano-AlN content on the microstructure and mechanical properties of SiC foam prepared by siliconization of carbon foam

Mesophase pitch (MP) was doped by nano-AlN to produce carbon foams followed by liquid silicon infiltration to prepare silicon carbide foams. Experiments have been carried out to investigate the effects of nano-AlN doping on bending strength and thermal shock resistance of the silicon carbide foams. Microstructure observation and phase identification indicate that AlN doping strengthens the silicon carbide foams by grain refining and solid-solution reaction. With 13 wt.% of nano-AlN, silicon carbide foams were obtained with the highest quality in bending strength of 14.1 MPa, thermal shock resistance, and bulk density of 0.73 g/cm³.     

The evolution of polyacetylene morphology upon doping

Knowledge of the evolution of the fibrillar morphology of polyacetylene with doping is critical for an understanding of the chemistry of the doping process, the mechanisms for charge transport in the polymer and the insulator-metal transition. Earlier scanning electron microscopic (SEM) studies reported conflicting results of either swelling of the fibrils or a gross morphological change. In order to resolve these differences, SEM experiments were carried out to compare the changes in apparent morphology due to the use of various coatings and coating methods used to reduce charging effects, the effects of tearing on the cross sectional morphology and the effects of contrast in imaging the samples. Results definitively show that the fibrillar morphology is retained upon doping.     

High-temperature dielectric and relaxation behavior of Yb-doped Bi0.5Na0.5TiO3 ceramics

Microstructure, phase transition and dielectric properties of Yb-doped Bi_0.5Na_0.5TiO₃ (BNT) ceramics were investigated. It is found that ytterbium promotes the grain growth and densification of the ceramics while Ti-rich impurity appears due to the compensation of Ti-vacancy. The dielectric operational temperature range of the ceramics with a±15% tolerance was greatly broaden until 500 °C by ytterbium doping. Meanwhile, the diffuseness of the diffuse phase transition increases with the increase of doping Yb. BNT ceramics with 3 mol% Yb doping shows a near-plateau dielectric behavior in a broad temperature range from 147 to 528 °C and a low dielectric loss (<0.025) from 154 to 356 °C, indicating that it is a promising material for applications in high-temperature capacitor.     

添加聚乙烯醇改善三氧化钨电致变色薄膜性能的研究

为改善三氧化钨薄膜的电致变色性能,采用钨粉过氧化聚钨酸溶胶-凝胶法制备了添加聚乙烯醇的三氧化钨电致变色薄膜.采用扫描电镜、紫外可见分光光度计和CHI电化学工作站分别测定和分析了三氧化钨薄膜的微观结构、光透过性能和循环伏安特性.结果表明,添加一定量的聚乙烯醇可使薄膜的结构更加平整,变色更为均匀;在着色态、褪色态下的光透过率之差达到60%以上,变色可调范围变大.电致变色可逆性能和光谱性能较不添加聚乙烯醇有所提高.     

Fe3+掺杂TiO2溶胶的低温制备及其光催化性能

采用溶胶-凝胶法在低温下制备出Fe3+掺杂TiO2(Fe3+/TiO2)溶胶,研究Fe3+掺杂对TiO2催化性能的影响,用TG/DTA技术分析TiO2粉末的热分解过程,用XRD、TEM等表征Fe3+掺杂对TiO2晶型、晶粒尺寸、晶粒形貌的影响,结果表明:Fe3+掺杂会对纳米TiO2晶粒的粒径及晶体形貌产生影响,抑制TiO2晶型由锐钛矿向金红石的转变。将亚甲基蓝作为目标污染物进行光催化降解试验,紫外-可见漫反射吸收光谱分析表明:经适量Fe3+掺杂后的TiO2溶胶光催化活性提高,当硝酸铁与钛酸丁酯的物质的量比为0.20%时,光催化活性最佳。     

TEM characterization of diblock copolymer templated iron oxide nanoparticles: Bulk solution and thin film surface doping approach

The morphology of a novel diblock copolymer, poly(norbornene methanol)-b-poly(norbornene dicarboxylic acid), was investigated before and after metal oxide doping by transmission electron microscopy (TEM) using a novel iodine vapor staining method to image the undoped polymer. A lamellar morphology was observed by TEM after staining the undoped diblock copolymer with iodine vapor. Thin film surface doping resulted in a confinement of the iron oxide nanoparticles within the lamellar domains. Spherical nanoparticle aggregates were observed through a bulk solution doping method. It was observed that the particles were templated by the underlying lamellar structure of the copolymer when the thin film surface doping method was used.     

Tunable surface plasmon resonance frequencies of monodisperse indium tin oxide nanoparticles by controlling composition,size, and morphology

Monodisperse indium tin oxide nanoparticles (ITO NPs) with high crystallinity have been synthesized by the rapid thermal injection method and the seed-mediated growth method. We demonstrate that the surface plasmon resonance (SPR) frequencies of ITO NPs can be manipulated from 1,600 to 1,993 nm in near-infrared band by controlling the composition, size, and morphology. The doping Sn concentration in ITO NPs could be controlled via changing the %Sn in the initial feed from 0% to 30%. The shortest SPR wavelength at 1,600 nm with 10% Sn doping concentration indicates highest free electron carrier concentration in ITO NPs, which has direct relationship with doping Sn⁴⁺ ions. Furthermore, we demonstrate that the SPR peaks can also be tuned by the size of ITO NPs in the case of uniform doping. Besides, compared with the ITO NPs, single crystalline ITO with nanoflower morphology synthesized through the one-pot method exhibit SPR absorption peak features of red-shifting and broadening.     

Effect of concentration of Fe-dopant on the photoelectrochemical properties of Titania nanotube arrays

TiO₂ nanotubes have attracted great attention because of their photoelectrochemical activity. Metallic doping using a simple and rapid synthesizing approach can be a way to enhance this application. This paper describes a novel one-step anodization synthesis of Fe-doped TiO₂ nanotubes with various concentrations of iron doping. FESEM, XRD, and EDX were used to analyze the effect of doping concentration on the morphology, structure, and composition of the prepared samples respectively, and the results showed the formation of the anatase phase of TiO₂ nanotube arrays with Fe incorporation in the TiO₂ lattice. Although the Fe insertion in the TiO₂ lattice leads to better crystallinity, the non-uniformity in the morphology of doped samples suggests that adequate doping is required to maintain uniformity in the morphology. The absorption spectra of all the Fe-doped TiO₂ samples showed a red shift in their absorption edges compared to pristine TiO₂. This shift was observed more in the samples with higher doping concentrations. The photocurrent density of Fe-doped samples was observed to be significantly higher than that of the pristine TiO2 sample. This improvement was found to be concentration-dependent, with the best results being obtained from a sample doped at a level of 0.5%. The samples also showed high photostability, which, together with the increased photocurrent density, points to Fe-doped TiO₂ as a promising photoanode material.