Effect of substrate temperature on morphology and electrochemical performance of radio frequency magnetron sputtered lithium nickel vanadate films used as negative electrodes for lithium microbatteries

Lithium nickel vanadate thin films were prepared by radio frequency magnetron sputtering at various substrate temperatures (Ts). These thin films have been investigated as anode electrode material in the use of microbatteries. Films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, glancing-incidence X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and high-resolution transmission electron microscopy techniques. The anodic electrochemical performances of the films have been evaluated by cyclic voltammetry at a scan rate of 1 mV/s and by galvanostatic cycling, with lithium metal as the counter and the reference electrode, and cycled in the range of 0.02-3.0 V at a current density of 75 microA/cm2. Thin films prepared at a Ts of 650 degrees C show a discharge capacity at the 20th cycle of 1100 (+/-10) mAh/g, which exhibited excellent capacity retention with a small capacity fade.     

Structural and electrochemical studies of annealed LiNiVO4 thin films

We prepared stoichiometric lithium nickel vanadate amorphous thin films by using r.f. magnetron sputtering under controlled oxygen partial pressure. The amorphous films were heated at various temperatures, 300–600 °C, for 8 h. The as‐deposited and annealed thin films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, X‐ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochemical behavior of the various films was studied by the galvanostatic method. The cells were tested in a liquid electrolyte at room temperature, with lithium metal used as the counter and reference electrode. The best electrochemical storage value was obtained with the thin film annealed at 300 °C, which showed superior capacity and small capacity loss during cycling. Copyright © 2007 John Wiley & Sons, Ltd.     

Characterization of non-stoichiometric co-sputtered Ba0.6Sr0.4(Ti1???x Fe x )1?+?x O3???δ thin films for tunable passive microwave applications

The fabrication of novel iron-doped barium strontium titanate thin films by means of radio frequency (RF) magnetron co-sputtering is shown. Investigations of the elemental composition and the dopant distribution in the thin films obtained by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and time-of-flight secondary ion mass spectroscopy reveal a homogeneous dopant concentration throughout the thin film. The incorporation of the iron dopant and the temperature-dependent evolution of the crystal structure and morphology are analyzed by electron paramagnetic resonance spectroscopy, X-ray diffraction, Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. In summary, these results emphasize the RF magnetron co-sputter process as a versatile way to fabricate doped thin films.     

Impact of high N2 flow ratio on the chemical and morphological characteristics of sputtered N‐DLC films

Because of their outstanding characteristics, diamond‐like carbon (DLC) thin films have been recognized as interesting materials for a variety of applications. For this reason, the effects of the incorporation of different elements on their fundamental properties have been the focus of many studies. In this work, nitrogen‐incorporated DLC films were deposited on Si (100) substrates by DC magnetron sputtering of a graphite target under a variable N₂ gas flow rate in CH₄ + N₂ + Ar gas mixtures. The influence of high N₂ flow ratios (20, 40 and 60%) on the chemical, structural and morphological properties of N‐DLC films was investigated. Different techniques including field emission gun‐equipped scanning electron microscope (FEG‐SEM), energy‐dispersive X‐ray spectroscopy (EDS), atomic force microscopy (AFM), profilometry, Rutherford backscattering spectrometry (RBS) and Raman spectroscopy (325‐nm and 514‐nm excitation) were used to examine the properties of the N‐DLC films. Thus, the incorporation of nitrogen was correlated with the morphology, roughness, thickness, structure and chemical bonding of the films. Overall, the results obtained indicate that the fundamental properties of N‐DLC films are not only related to the nitrogen content in the film but also to the type of chemical bonds formed. Copyright © 2016 John Wiley & Sons, Ltd.     

The properties of BCN films formed by ion beam assisted deposition

A study has been made on the formation and the properties of boron carbonnitride (BCN) thin films. The BCN films were produced by ion beam assisted deposition, in which boron and carbon were deposited by electron beam heating and nitrogen was supplied by ion implantation simultaneously. The mechanical properties of BCN films were measured using a ultra micro hardness tester and a friction tester. The atomic ratio and the structure of BCN thin films were estimated by means of X-ray photoelectron spectroscopy, laser Raman spectroscopy and Fourier transform infrared spectroscopy. As preliminary results, it was found that the BCN films are higher in hardness and lower in friction coefficient than diamond-like carbon (DLC) films. The mechanical properties are discussed with the relation of surface composition and structure.     

Enhanced electron field emission from ZnO nanoparticles-embedded DLC films prepared by electrochemical deposition

ZnO nanoparticles-embedded diamond-like amorphous (DLC) carbon films have been prepared by electrochemical deposition. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) results confirm that the embedded ZnO nanoparticles are in the wurtzite structure with diameters of around 4 nm. Based on Raman measurements and atomic force microscope (AFM) results, it has been found that ZnO nanoparticles embedding could enhance both graphitization and surface roughness of DLC matrix. Also, the field electron emission (FEE) properties of the ZnO nanoparticles-embedded DLC film were improved by both lowering the turn-on field and increasing the current density. The enhancement of the FEE properties of the ZnO-embedded DLC film has been analyzed in the context of microstructure and chemical composition.     

液相脉冲激光烧蚀法制备高熔点的纳米金属粒子

采用液相脉冲激光烧蚀法成功地制备了高熔点的金属Pt、Ru与Ag纳米粒子. 采用SEM、TEM、ED和紫外-可见吸收光谱表征了纳米粒子的特征. 纳米粒子的粒径基本在数个到数十个纳米的大小范围内. 发现含适量PVP(poly(vinylpyrrolidone))的水溶液有利于纳米粒子的制备, 而且还能够提高纳米粒子悬浮液的稳定性. 该制备方法较简单, 在制备高熔点的纳米金属粒子方面有着其它方法所不能比拟的优势.     

Structural stability and phase transitions in WO3 thin films

Tungsten oxide (WO3) thin films have been produced by KrF excimer laser (lambda = 248 nm) ablation of bulk ceramic WO3 targets. The crystal structure, surface morphology, chemical composition, and structural stability of the WO3 thin films have been studied in detail. Characterization of freshly grown WO3 thin films has been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy (RS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) measurements. The results indicate that the freshly grown WO3 thin films are nearly stoichiometric and well crystallized as monoclinic WO3. The surface morphology of the resulting WO3 thin film has grains of approximately 60 nm in size with a root-mean-square (rms) surface roughness of 10 nm. The phase transformations in the WO3 thin films were investigated by annealing in the TEM column at 30-500 degrees C. The phase transitions in the WO3 thin films occur in sequence as the temperature is increased: monoclinic --> orthorhombic --> hexagonal. Distortion and tilting of the WO6 octahedra occurs with the phase transitions and significantly affects the electronic properties and, hence, the electrochemical device applications of WO3.     

LiF-Ni纳米复合薄膜的电化学性能研究

采用脉冲激光沉积法在不锈钢基片上制备了LiF-Ni纳米复合薄膜, 用充放电和循环伏安实验测量了该薄膜的电化学性能. 首次充电容量为107 mAh•g−1, 它对应第一次释放锂的过程. 在充放电循环过程中, 锂的嵌入、脱出通过非原位高分辨电子显微和选区电子衍射得到证实. 这一结果为LiF可以由过渡金属Ni驱动分解提供了直接的实验证据.     

不锈钢上液相电沉积类金刚石薄膜

以甲醇有机溶液作碳源,应用直流脉冲电化学沉积方法,在不锈钢表面制备了类金刚石碳薄膜.用原子力显微镜、扫描电镜、拉曼光谱仪和傅立叶红外吸收光谱表征该薄膜的表面形貌和结构.结果表明:经电化学沉积的含氢类金刚石碳薄膜均匀、致密,表面粗糙度小;Raman光谱在1 332.51cm-1处有一强的谱峰,与金刚石的特征谱峰相重合.加入活性添加剂,增加了电流密度,使沉积速率提高到0.5μm/h.     

A comparative study of the polyaniline thin films produced by the cluster beam deposition and laser ablation methods

Polyaniline (PANI) thin films have been prepared by applying the novel neutral and ionized cluster beam deposition (NCBD and ICBD) methods and the pulsed laser deposition (PLD) technique to the PANI samples of half-oxidized emeraldine base (EB-PANI) and protoemeraldine base forms in a high-vacuum condition. Characterization of the oxidation states and structural changes of pristine and doped thin films has been performed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and x-ray photoelectron spectroscopy. Spectroscopic measurements demonstrate that the dominant structure of NCBD and ICBD thin films corresponds to the reduced leucoemeraldine base state, whereas the chemical composition of PLD thin films depends critically on the laser fluence and the molecular weight of PANI target. The congruent deposition is only obtained for the PLD films deposited by the laser-induced decomposition of the low-molecular-weight targets in the low to intermediate fluence regime (below 100 mJ/cm2 with a pulse duration of 7 ns). The surface morphology examined by atomic force microscopy measurements shows that the cluster and laser beams are effective in producing smooth, uniform polymeric thin films. After I2 and HCl doping, the electrical conductivities of the NCBD, ICBD, and particularly PLD thin films are increased significantly. The higher conductivity of PLD films is ascribed to higher amounts of quinoid di-imine doping sites in the EB-PANI state, and the overall structure-conductivity characteristics are consistent with the spectroscopic observations.     

Superhard coatings — Production and analysis

In the development of diamond and c-BN products the analytical methods for characterizing the surface, bulk and interface of the diamond coatings are very important. SEM, Raman, XRD and IR are the methods used for characterization and SIMS, TEM, AES, NRA, RBS, XPS, STM, etc. are used for the investigation of special problems. The techniques for diamond and c-BN production are briefly summarized to give an idea of the complex interactions between production, application and analytical characterization. The analytical methods for diamond characterization and many relevant results are summarized in this paper; some physical properties (e.g. thermal conductivity, transparency, etc.) and their interaction with applications are also discussed.Abbreviations AES Auger electron spectroscopy - AFM atomic force microscopy - c-BN cubic boron nitride - CL cathodoluminescence - CVD chemical vapour deposition - EELS electron energy loss spectroscopy - EPMA electron probe microanalysis - ERDA elastic recoil detection analysis - h-BN hexagonal boron nitride - HP-HT high-pressure high-temperature - HF hot-filament - IR infra-red - LEED low energy electron diffraction - MW microwave - NAA neutron activation analysis - NRA nuclear reaction analysis - PL photoluminescence - PVD physical vapour deposition - RBS Rutherford backscattering spectrometry - RHEED reeflected high energy electron diffraction - SAD selected area diffraction - SEM scanning electron microscopy - SIMS secondary ion mass spectrometry - STM secondary ion mass spectrometry - TEM transmission electron microscopy - TMB trimethylborate - XPS X-ray photoelectron spectroscopy - XRD X-ray diffraction Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Analysis of corrosion processes at the surface of diamond-like carbon protected zinc selenide waveguides

A detailed surface analytical study on the corrosion behavior of unprotected and diamond-like carbon (DLC)-coated mid-infrared (MIR) waveguides used in remote sensing applications at strongly oxidizing conditions is presented. High-quality DLC films, with a thickness of 100 nm serving as MIR-transparent corrosion barrier, have been produced at the surface of zinc selenide (ZnSe) attenuated total reflection waveguides via pulsed laser deposition techniques. IR microscopy and atomic force microscopy are applied to investigate the chemical inertness of DLC-based membranes against aqueous solutions of hydrogen peroxide. These stability studies show that uncoated ZnSe waveguides are subject to severe chemical surface modifications, while DLC-protected waveguides maintain their optical properties and chemical integrity. In situ studies on the corrosion behavior by a recently developed approach combining scanning electrochemical microscopy (SECM) with Au/Hg amalgam ultramicroelectrodes in a scanning stripping voltammetry experiment provides additional insight into the mechanisms of the corrosion process. It is demonstrated that the combination of surface analytical techniques and, in particular, the innovative application of SECM with amalgam electrodes provides superior information on corrosion processes at the surface of optical waveguides. This detailed study confirms the efficiency of protective DLC coatings deposited onto IR-transparent optical waveguides, rendering this novel concept ideal for sensing applications in harsh environments.     

Atomic layer deposition of the titanium dioxide thin film from tetraethoxytitanium and water

Using the methods of Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction in the geometry of the grazing beam, and Fourier transform infrared spectroscopy, we studied the chemical composition and structure of thin films of titanium dioxide formed by atomic layer deposition from tetraethoxytitanium and water. It is shown that the films obtained are characterized by a high stoichiometry of composition and by amorphous or polycrystalline structure of the anatase modification, depending on the number of reaction cycles. Using a model of the process of atomic layer deposition that takes into account the size and number of ligands of the reacting molecules, we calculated the amount of titanium dioxide deposited in a single reaction cycle.     

Electrodeposited noble metal particles in polyelectrolyte multilayer matrix as electrocatalyst for oxygen reduction studied using SECM

Taking the advantage of the stability and penetrability of polyelectrolyte films formed by layer-by-layer (LbL) deposition, noble metal particles of Pd and Pt were fabricated in a preformed polyeletrolyte multilayer film by galvanic deposition. The metal deposition occurred as metal particles and they were tested for their properties as electrocatalyst for oxygen reduction. Atomic force microscopy (AFM) was used to characterize the morphology of the particle films. The noble metal particles were investigated by cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM) with respect to oxygen reduction. The results show that the electrocatalytic properties of the Pd particle film can be adjusted by the electrodeposition time. The hydrogen peroxide formed as an intermediate during electroreduction of dioxygen was conveniently measured in the SECM using the substrate-generation/tip-collection mode. The relevance of the main reduction pathways could be extracted from fitting the current transients to an analytical model.     

脉冲激光沉积CuF2薄膜的电化学性能

采用脉冲激光沉积法在不锈钢基片上制备了纳米结构的CuF2薄膜, 其充放电性能显示该薄膜具有540 mAh·g-1可逆容量, 对应于每个CuF2可与2.0个Li发生反应. 其循环伏安特性显示在2.2和2.8 V (vs Li/Li+)处出现了一对新的氧化还原峰. 充放电后薄膜的组成与结构通过非原位高分辨电子显微和选区电子衍射来表征. 结果揭示了纳米结构CuF2薄膜的电化学反应机理, LiF在过渡金属Cu的驱动下可以发生可逆的分解和形成.     

Mn4N薄膜与锂的电化学反应性能

采用脉冲激光沉积辅助高压电离的方法在不锈钢基片上制备了Mn₄N薄膜. 用充放电和循环伏安测试对该薄膜电极的电化学性能进行了表征. 该薄膜电极的首次放电容量为420 mAh•g^-1, 第一次充放电不可逆容量约为50%. 采用XRD, XPS, SEM对薄膜的化学组成和表面形貌进行了表征, 并对反应机理进行了研究, 结果表明Mn4N在反应过程中转化为金属Mn和Li₃N, 只有部分的Mn与Li₃N参与了可逆的电化学反应.     

The fabrication of layer‐by‐layer mode LaCoO3 film by pulsed laser deposition

The relationship between strain and growth conditions in LaCoO₃ thin film was obtained to control the magnetic‐electric characteristics. The LaCoO₃ thin films on the SrTiO₃ substrates have been achieved by the pulsed laser deposition method, and the reflection high‐energy electron diffraction method (RHEED) was applied to monitor the growth process in situ; the layer‐by‐layer growth mode was discovered. The X‐ray diffraction and atomic force microscopy were applied to the phase analysis, and the layer thickness and the layer‐by‐layer growth mode were uncovered. Compared with the 100‐nm LaCoO₃ thin films, the strain in the layer‐by‐layer ultra thin film was more controllable. The enhanced magnetic properties of the layer‐by‐layer mode ultra‐thin films could be tested in future work.     

Formation of binary and ternary metal deposits on glass–ceramic carbon electrode surfaces: electron-probe X-ray microanalysis,total-reflection X-ray fluorescence analysis,X-ray photoelectron spectroscopy and scanning electron microscopy study

The features of the formation of binary and ternary alloys during the electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass–ceramic carbon electrode surfaces were studied by electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The macroscopic properties of electrodeposits such as morphology, lateral distribution of the elements along the disc electrode surface and depth distribution of the elements in the electrodeposit bulk were established. The mechanisms of metal nucleation and growth of thin films of electrodeposits were discussed.     

纯相Li_2MnO_3薄膜的制备及作为锂离子电池正极材料的电化学行为

采用固相烧结法制备了纯相Li2MnO3正极材料及靶材,采用脉冲激光沉积(PLD)法在氧气气氛、不同温度下沉积了Li2MnO3薄膜.通过X射线衍射(XRD)和拉曼(Raman)光谱表征了薄膜的晶体结构,采用扫描电镜(SEM)观察薄膜形貌及厚度,利用电化学手段测试了Li2MnO3薄膜作为锂离子电池正极材料性能.结果表明,PLD方法制备的纯相Li2MnO3薄膜随着沉积温度升高薄膜结晶性变好.25℃沉积的薄膜难以可逆充放电,400℃沉积的薄膜具有较高的电化学活性和循环稳定性.相对于粉末材料,400与600℃制备的Li2MnO3薄膜电极平均放电电位随着循环次数的衰减速率明显低于相应的粉体材料.