晶粒尺寸对氧化钒薄膜电学与光学相变特性的影响

采用直流对靶磁控溅射方法制备氧化钒薄膜,通过改变热处理温度获得了具有不同晶粒尺寸的相变特性氧化钒薄膜,对氧化钒薄膜相变过程中电阻和红外光透射率随温度的突变性能进行研究.结果表明:经300℃和360℃热处理后,薄膜内二氧化钒原子分数达到40%,氧化钒薄膜具有绝缘体-金属相变特性,薄膜的晶粒尺寸分别为50nm和100nm;...     

氩流量对氧化钒薄膜直流磁控溅射制备的影响

在氧化钒薄膜的直流磁控溅射制备中,氩流量是影响沉膜工艺以及薄膜织构和性能的重要因素之一.从氧化钒薄膜制备角度出发,研究了纯氩环境以及氧流量恒定的氩氧混合环境中溅射电压和薄膜沉积速率随氩流量的变化.实验结果有助于对氧化钒薄膜制备工艺进行优化,为氩气流量的选择提供参考.     

直流磁控溅射Ni49.54Mn29.59Ga20.87磁驱动记忆合金薄膜的XPS研究

采用直流磁控溅射技术沉积了Ni49.54Mn29.59Ga20.87磁驱动形状记忆合金薄膜.XRD结果表明,Ni49.54Mn29.59Ga20.87薄膜室温下为5层调制型结构马氏体.X射线光电子能谱(XPS)分析表明,放置于空气中2个月的沉积态薄膜表面吸附少量氧和碳杂质.随Ar 刻蚀深度的增加,表面C杂质易被剥蚀掉,而部分氧杂质以MnO状态存在;Ni、Mn、Ga元素含量由薄膜表面向内层逐渐增加,化学价由正价向零价转变.     

热处理对V2O5-TiO2复合薄膜表面结构与光学性能的影响

以钛酸丁脂、V2O5粉末为前驱体,采用溶胶-凝胶法制备了V2O5-TiO2复合薄膜,并采用X射线光电子能谱(XPS)和Uv-vis-nir分光光度计等方法研究了热处理对薄膜性能的影响.结果表明,随热处理温度的升高,复合薄膜中钛离子的价态不变,仍为Ti4 ;而V4 离子逐渐被氧化为V5 离子;并采用氢氧基团、碳氧键与多种钒离子进行叠加拟合,拟合结果与实验曲线非常符合;V2O5-TiO2复合薄膜在紫外光波段的透射率减小,吸收带边出现红移.     

钒掺杂二氧化钛薄膜制备与材料特性分析

以钛酸四丁酯和乙酰丙酮钒（Ⅲ）为主要原料,采用溶胶-凝胶法制备了钒掺杂二氧化钛薄膜,利用XRD、紫外-可见吸收光谱、FT-IR及XPS等表征手段,将其与未掺杂二氧化钛薄膜进行了材料特性对比研究。结果表明两种薄膜均为锐钛矿结构,引入钒后二氧化钛的禁带宽度由3.28eV减小至3.15eV,吸收带边红移至可见光范围;XPS分析证实制备的钒掺杂二氧化钛薄膜中钒以四价和五价两种氧化价态存在,可能在二氧化钛禁带中引入较深的杂质能级而引起价带顶向禁带拓展,从而产生引起禁带宽度变窄效应,扩展了二氧化钛带边光吸收。理论分析还表明,钒掺杂引起的深能级杂质在二氧化钛晶界处易于形成有效的陷阱俘获光生空穴,从而抑制光生载流子的复合,尤其适于用作光催化材料。     

氧化钒薄膜的制备技术及特性研究

采用直流反应磁控溅射法,通过精确控制反应溅射电压优化了氧化钒薄膜的制备工艺.对制备的氧化钒薄膜,利用四探针测试仪检测了薄膜的方阻和方阻温度系数,用X射线光电子能谱(XPS)仪和原子力显微镜(AFM)对薄膜的钒氧原子比和薄膜的微观形貌分别进行了分析和表征.实验结果表明,利用精确控制反应溅射电压法生长出的氧化钒薄膜的性能得到了进一步的提高.     

氧化钒薄膜的厚度对薄膜电学特性的影响

利用直流反应磁控溅射法在表面覆盖有Si3N4薄膜的Si(100)基片上制备了不同厚度的氧化钒薄膜.用光谱式椭偏仪对薄膜的厚度进行了测试.采用四探针测试系统对制备的薄膜进行了方阻和方阻温度系数的分析,发现薄膜的厚度对薄膜的电学特性有很大的影响.实验结果表明氧化钒薄膜的厚度调整可作为调控氧化钒薄膜性能的一种重要工艺手段.     

氧化钒薄膜的微观结构研究

采用直流反应磁控溅射法在不同基片上制备了80nm和1000nm厚的氧化钒薄膜.采用X射线衍射仪、原子力显微镜及扫描电镜进行了薄膜微观结构分析.结果表明,薄膜的晶化受衬底影响较大,晶化随膜厚的增加而增强.不同衬底上生长的薄膜晶粒尺寸存在较大差异,Si3N4/Si衬底上生长的薄膜晶粒细小,薄膜较为平坦;玻璃衬底、Si衬底和α-Al2O3陶瓷衬底上生长的薄膜晶粒较为粗大.随着膜厚的增加,薄膜的晶粒尺寸明显增大,不同衬底上生长的二氧化钒薄膜晶粒都具有一种独特的"纺锤"形或"棒"形.     

焦钒酸镍的X射线光电子能谱及其氧化脱氢催化性能研究

采用微波草酸盐共沉淀法制备了焦钒酸镍Ni2V2O7催化剂,并用XRD、BET、H2-TPR、XPS、TEM和电导等技术表征.研究了Ni2V2O7催化剂的丙烷氧化脱氢(ODH)制丙烯催化性能与其表面物种的关系.TPR和XPS实验结果显示p型半导体焦钒酸镍Ni2V2O7催化剂中,晶格氧可以较容易转换成未完全还原氧,使催化剂内各种价态的钒之间易于进行氧化还原反应并形成氧缺位,从而催化剂的表面含有较多未充分还原氧物种O-和V4 物种.从而使其具有较高的丙烯选择性.     

氧化钒薄膜的制备技术及特性研究

采用直流反应磁控溅射法，通过精确控制反应溅射电压优化了氧化钒薄膜的制备工艺。对制备的氧化钒薄膜，利用四探针测试仪检测了薄膜的方阻和方阻温度系数，用X射线光电子能谱（XPS）仪和原子力显微镜（AFM）对薄膜的钒氧原子比和薄膜的微观形貌分别进行了分析和表征。实验结果表明，利用精确控制反应溅射电压法生长出的氧化钒薄膜的性能得到了进一步的提高。     

Nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition

Nano-polycrystalline vanadium oxide thin films have been successfully produced by pulsed laser deposition on Si(100) substrates using a pure vanadium target in an oxygen atmosphere. The vanadium oxide thin film is amorphous when deposited at relatively low substrate temperature (500 degrees C) and enhancing substrate temperature (600-800 degrees C) appears to be efficient in crystallizing VOx thin films. Nano-polycrystalline V3O7 thin film has been achieved when deposited at oxygen pressure of 8 Pa and substrate temperature of 600 degrees C. Nano-polycrystalline VO2 thin films with a preferred (011) orientation have been obtained when deposited at oxygen pressure of 0.8 Pa and substrate temperatures of 600-800 degrees C. The vanadium oxide thin films deposited at high oxygen pressure (8 Pa) reveal a mix-valence of V5+ and V4+, while the VOx thin films deposited at low oxygen pressure (0.8 Pa) display a valence of V4+. The nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition have smooth surface with high qualities of mean crystallite size ranging from 30 to 230 nm and Ra ranging from 1.5 to 22.2 nm. Relative low substrate temperature and oxygen pressure are benifit to aquire nano-polycrystalline VOx thin films with small grain size and low surface roughness.     

基于组合薄膜制备技术的成分梯度薄膜(La1-xCax)VO3 (0≤x≤1)的制备和热电性能研究

采用"组合激光溅射制膜技术",制备了高质量(La1-xCax)VO3(0≤x≤1)成分梯度薄膜。采用组合热电测量系统和组合XRD系统测量了(La1-xCax)VO3(0≤x≤1)成分梯度薄膜的热电性能和晶体结构。在0≤x≤1范围内,(La1-xCax)VO3形成了固溶体。800℃生长的LaVO3薄膜具有最大的功率因数(α)值0.6μW/cm K2。V离子化学价对LaVO3的热电性能影响很大,当它由+3向+2变化时,可能获得良好的热电性能。     

Oxidation of vanadium with reactive oxygen plasma: A photoelectron spectroscopy study of the initial stages of the oxide growth process

We report on the oxidation of vanadium surface in a low-temperature oxygen plasma studied by in-situ photoelectron spectroscopy (XPS, UPS). Pure vanadium foil was exposed to the oxygen plasma for different time intervals allowing to investigate early stages of the oxide-metal interface formation process and the oxide film growth. Upon increasing the exposure time to the oxygen plasma we identify two regimes with respect to the vanadium oxidation state: formation of 4+ state on the early stages of growth and in saturated regime vanadium was found to be predominantly in the 5+ oxidation state. Angle-resolved XPS was used to perform an in-depth distribution analysis of chemical composition in outermost layers of the oxide. We found that plasma oxidation produces a well-pronounced interface with a transition layer thickness of about 1.3 nm.     

6H-SiC单晶表面ZnO薄膜的制备及其结构表征

利用脉冲激光淀积(PLD)技术在6H-SiC单晶衬底上制备了ZnO薄膜. 利用X射线衍射(XRD), 反射式高能电子衍射(RHEED)和同步辐射掠入射X射线衍射(SRGID)φ扫描等实验技术研究了ZnO薄膜的结构. 结果表明:在单晶6H-SiC衬底上制备的ZnO薄膜已经达到单晶水平, 不同入射角的SRGID结果, 显示了ZnO薄膜内部不同深度处a方向的晶格弛豫是不一致的, 从接近衬底界面处到薄膜的中间部分再到薄膜的表面处, a方向的晶格常数分别为0.3264、0.3272和0.3223nm. 通过计算得到ZnO薄膜的泊松比为0.504, ZnO薄膜与单晶6H-SiC衬底在平行于衬底表面a轴方向的实际晶格失配度为5.84%.     

Synthesis of vanadium oxide nanotubes from V2O5 sols

Vanadium oxide nanotubes (VO_x-NTs) were prepared by using V₂O₅ sols as precursor for the first time with hexadecylamine (HDA) as structure-directing template via a modified sol–gel method followed by hydrothermal treatment. Structure and morphology of the nanotubes were investigated by XRD, SEM, HRTEM, TGA, FT-IR and XPS. The obtained nanotubes were found having outer diameters from 30 to 100 nm and inner diameters from 10 to 30 nm with length up to several micrometers. It is also confirmed that water molecules enter vanadium oxide layers together with structure-directing template and the low valence vanadium occurs in the VO_x-NTs.     

Giant phase transition properties at terahertz range in VO₂ films deposited by sol-gel method

VO(2) films were fabricated on high-purity single-crystalline silicon substrate by the sol-gel method, followed by rapid annealing. The composition and microstructure of the films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The results indicated a polycrystalline nature with high crystallinity and compact nanostructure for the films, and the concentration of +4 valence vanadium is 79.85%. Correlated with these, a giant transmission modulation ratio about 81% of the film was observed by terahertz time domain spectroscopy. The experimentally observed transmission characteristics were reproduced approximately, by a simulation at different conductivities across the phase transition. According to the effective-medium theory, we assumed that it is important to increase the concentration of +4 valence vanadium oxide phases and improve the compactness of the VO(2) films for giant phase transition properties. The sol-gel-derived VO(2) films with giant phase transition properties at terahertz range, and the study on their composition and microstructure, provide considerable insight into the fabrication of VO(2) films for the application in THz modulation devices.     

XPS and AFM studies of monodispersed Pb/PbO core-shell nanostructures

A probe of the core-shell formation and the interfacial properties of monodispersed 30 nm Pb nanoparticles are presented. A direct correlation between the structures of the particle to its chemical states is done, by a careful Ar+ ion depth profiling followed by X-ray Photoelectron Spectroscopy and Atomic Force Microscopy. The study provides a unique insight into the structure of the nanoparticles. A PbO shell of 4 nm is observed to cover a 15-nm core, with a 5 nm interfacial region. The valence band spectra show the movement of the valence band maxima towards and beyond the Fermi-level during the insulator to metal transition along the particle depth. Evidence is also provided for an enhanced preferential sputtering of the PbO shell and an ion induced penetration of PbO into the Pb core.     

锂离子注入对V2O5薄膜红外振动特性影响

用反应蒸发法制备了多晶Ｖ２Ｏ５薄膜,采用两电极多锂离子电解质向Ｖ２Ｏ５薄膜注入锂离子,测试了离子注入前后薄膜的红外反射光谱,实验结果表明,锂离子注入对Ｖ２Ｏ５晶体红外振动影响较大。采用多晶Ｖ２Ｏ５振动模型分析了薄膜的红外振动吸收,并得到了锂离子注入产生的Ｖ２Ｏ５薄膜振动的变化是由于晶格扩展和钒离子自身杂质形成引起的。     

Ni2+掺杂ZnO薄膜及粉体的结构和发光性能研究

采用激光脉冲沉积法,用XeCl准分子激光器在Si (100)基片、真空和5Pa氧气气氛下制备了Ni2+(0.8％(原子分数))掺杂的呈六角纤锌矿结构的ZnO薄膜.氧气气氛下制备的薄膜沿(002)取向生长,表面比较平整,平均颗粒尺寸为80nm.真空条件下制备的薄膜出现Zn2SiO4杂相,平均颗粒尺寸为150nm.和真空条件下制备的薄膜相比,氧气气氛下制备的薄膜具有较强的ZnO本征发光,在425nm附近出现由于填隙Zn缺陷引起的较宽的蓝光发光带,并且在482nm处出现了由于氧空位和氧间隙间的转换引起的较强的蓝光发光峰,同时由于氧缺陷引起的449nm附近的蓝光发光峰强度明显降低.