Ion beam assisted texturing of polycrystalline Y2O3 films deposited via electron-beam evaporation

Ion-beam assisted deposition of polycrystalline Y₂O₃ films using e-beam evaporation was investigated. For growth on non-crystalline substrates, low temperature growth yields randomly oriented polycrystalline material. At elevated temperature, surface energy anisotropy yields a (111) uniaxial texture. For film deposition with irradiation from an Ar ion beam, the out-of-plane texture remained (111) in orientation. The incident Ar ion beam induces an in-plane alignment of the Y₂O₃ films that is relatively broad. A six-fold symmetry in the out-of-plane X-ray diffraction phi-scans was observed for the (111) textured Y₂O₃ films, indicating a multi-variant in-plane texture and suggesting anisotropic damage along both the (110) and (100) projections. The lack of a sharp, single variant in-plane texture with ion beam irradiation is consistent with the relatively weak bond strength in Y₂O₃.     

Yttrium sesquioxide, Y2O3, thin films deposited on Si by ion beam sputtering: microstructure and dielectric properties

Y₂O₃ thin films were in-situ deposited by ion beam sputtering on Si substrate. The influence of the deposition parameters are studied by X-ray diffraction, electrical measurements and high resolution transmission electron microscopy observations. The stress sate of the oxide layers is investigated by the sin²ψ method as a function of the deposition parameters and the post-annealing treatments. Oxygen ion beam assisted deposition process or post-annealing of as-deposited thin films lead to the same relaxation of the internal compressive stress within the oxide layer. An SiO₂ layer sandwiched between Si and Y₂O₃ is always observed and should play a role both in the growing process and electrical properties of the MOS structure based on Y₂O₃ oxide layer. The results are interpreted in terms of diffusional process in the oxide, which are directly related to the temperature and the oxygen partial pressure during the growth process.     

Effects of deposition parameters on the crystallinity of CeO2 thin films deposited on Si(100) substrates by r.f.-magnetron sputtering

Deposition temperature, r.f.-power and seed layer deposition time were important parameters effecting the crystallinity of CeO₂ thin films deposited by r.f.-magnetron sputtering on Si(100) substrates. The CeO₂ (200) peak was notable for a deposition temperature above 600°C. With decreased r.f.-power and thus lower deposition rate, the intensity of the CeO₂(200) peak increased. When the seed layer deposition time was less than 20 s, the CeO₂(200) peak dominated. Transmission electron microscopy (TEM) diffraction revealed that the deposited CeO₂ thin film had a polycrystalline structure. Annealing at 950°C in O₂ atmosphere for 30 min increased and sharpened the CeO₂(200) peak.     

Low-temperature epitaxial growth of conductive LaNiO3 thin films by RF magnetron sputtering

Epitaxial growth of LaNiO₃ (LNO) thin films was successful on CeO₂/YSZ/Si(100), MgO(100) and SrTiO₃ (STO)(100) substrates by RF magnetron sputtering at 300 °C, although pulsed laser deposition requires 600 °C to prepare epitaxial LNO films according to the literature. Epitaxial LNO films deposited on CeO₂/YSZ/Si(100) and STO(100) had single orientation of LNO[100]//CeO₂[110]//YSZ[110]//Si[110]) and LNO[100]//STO[100], respectively. On the other hand, epitaxial LNO films deposited on MgO(100) had mixed orientations of LNO[100]//MgO[100] and LNO[100]//MgO[110]. The lattice parameter, composition and resistivity of the LNO thin films were strongly dependent on the substrate temperature. The minimum resistivity of LNO films was approximately 5×10⁻⁶ Ω m, which value almost agrees with the resistivity in the literature. It was found that the temperature to achieve minimum resistivity was 200 °C, irrespective of the type of substrate. The surface of the LNO films was smooth and flat.     

Growth of SrTiO3 thin epitaxial films by aerosol MOCVD

SrTiO₃ thin films were prepared by aerosol metal-organic chemical vapour deposition on (001) MgO, R-plane Al₂O₃ and (001) Si single-crystal substrates. Strontium tetramethyl heptadionate and titanium n-butoxide dissolved in diethyleneglycol dimethyl ether were used as precursors. The structure of the films was investigated by X-ray diffraction and transmission electron microscopy. Epitaxial films with [001] and [111] orientation perpendicular to the substrate surface were obtained on MgO and Al₂O₃, respectively. The epitaxial films on the MgO substrate were found to be in a relaxed state with lattice parameters corresponding to the bulk values. SrTiO₃ films on the Si substrate were grown as highly textured in the [011]direction and randomly oriented in the plane parrallel to the substrate surface.     

Preparation of Pt-PtOx thin films as electrode for memory capacitors

Pt-PtO_x thin films were prepared on Si(100) substrates at temperatures from 30 to 700°C by reactive r.f. magnetron sputtering with platinum target. Deposition atmosphere was varied with O₂/Ar flow ratio. The deposited films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Resistively of the deposited films was measured by d.c. four probe method. The films mainly consisted of amorphous PtO and Pt₃O₄ (or Pt₂O₃) below 400°C, and amorphous Pt was increased in the film as a deposition temperature increased to 600°C. When deposition temperature was thoroughly increased, (111) oriented pure Pt films were formed at 700°C. Compounds included in the films strongly depended on substrate temperature rather than O₂/Ar flow ratio. Electrical resistivity of Pt-PtO_x films was measured to be from the order of 10⁻¹ Ω cm to 10⁻⁵ Ω cm, which was related to the amount of Pt phase included in the deposited films.     

High-resolution and analytical transmission electron microscopy of epitaxial YBa2Cu3O7−x thin films and YBa2Cu3O7/PrBa2Cu3O7 superlattices

Transmission electron microscopy (TEM) studies of epitaxial YBa₂Cu₃O_7−x thin films and YBa₂Cu₃O₇/PrBa₂Cu₃O₇ superlattices are summarized. High-resolution imaging of cross-sections and plan views and energy-dispersive X-ray microanalysis and electron energy loss spectroscopy in the transmission electron microscope were the methods applied. In the first section results on YBa₂Cu₃O_7−x thin films With varying oxygen stoichiometry deposited onto SrTiO₃ are discussed. Then, YBa₂Cu₃O₇/PrBa₂Cu₃O₇ superlattices deposited onto SrTiO₃ and MgO are investigated. Finally, an interface analysis of high-quality YBa₂Cu₃O_7−x thin films deposited onto sapphire with yttrium-stabilized zirconia buffer layers is presented.     

Deposition of Sm2O3 doped CeO2 thin films from Ce(DPM)4 and Sm(DPM)3 (DPM=2,2,6,6-tetramethyl-3,5-heptanedionato) by aerosol-assisted metal–organic chemical vapor deposition

Samarium-doped ceria (SDC) thin films were prepared from Sm(DPM)₃ (DPM = 2,2,6,6-tetramethyl-3,5-heptanedionato) and Ce(DPM)₄ using the aerosol-assisted metal–organic chemical vapor deposition method. -Al₂O₃ and NiO-YSZ (YSZ = Y₂O₃-stabilized ZrO₂) disks were chosen as substrates in order to investigate the difference in the growth process on the two substrates. Single cubic structure could be obtained on either -Al₂O₃ or NiO-YSZ substrates at deposition temperatures above 450 °C; the similar structure between YSZ and SDC results in matching growth compared with the deposition on -Al₂O₃ substrate. A typical columnar structure could be obtained at 650 °C on -Al₂O₃ substrate and a more uniform surface was produced on NiO-YSZ substrate at 500 °C. The composition of SDC film deposited at 450 °C is close to that of precursor solution (Sm : Ce = 1 : 4), higher or lower deposition temperature will both lead to sharp deviation from this elemental ratio. The different thermal properties of Sm(DPM)₃ and Ce(DPM)₄ may be the key reason for the variation in composition with the increase of deposition temperature.     

New transparent conducting MgIn2O4---Zn2In2O5 thin films prepared by magnetron sputtering

New materials for a transparent conducting oxide film are demonstrated. Highly transparent Zn₂In₂O₅ films with a resistivity of 3.9 × 10⁻⁴ Ω cm were prepared on substrates at room temperature using a pseudobinary compound powder target composed of ZnO (50 mol.%) and In₂O₃ (50 mol.%) by r.f. magnetron sputtering. MgIn₂O₄---Zn₂In₂O₅ films were prepared using MgIn₂O₄ targets with a ZnO content of 0–100 wt.%. The resistivity of the deposited films gradually decreased from 2 × 10⁻³ to 3.9 × 10⁻⁴ Ω cm as the Zn/(Mg + Zn) atomic ratio introduced into the films was increased. The greatest transparency was obtained in a MgIn₂O₄ film. The optical absorption edge of the films decreased as the Zn/(Mg + Zn) atomic ratio was increased, corresponding to the bandgap energy of their materials. It was found that the resistance of the undoped Zn₂In₂O₅ films was more stable than either the undoped MgIn₂O₄, ZnO or In₂O₃ films in oxidizing environments at high temperatures.     

Line-focus acoustic microscopy measurements ofNb2O5/MgO and BaTiO3/LaAlO3thin-film/substrate configurations

Line-focus acoustic microscopy has been used to measure the phase velocities of surface acoustic waves on bare MgO and bare LaAlO₃ , and on Nb₂O₅/MgO and BaTiO₃/LaAlO₃ thin-film/substrate configurations. The thin films are polycrystalline materials. The substrates are anisotropic single-crystals. The measured angular variation of the surface acoustic wave velocities has been used to determine the elastic constants of MgO substrate and Nb₂O₅ thin-film. It has been assumed that the Nb₂O₅ films may be considered as essentially isotropic. The measurements for LaAlO₃ and BaTiO₃/LaAlO₃ show anomalies which are attributed to twinning in the LaAlO₃ substrate     

Optimization of spectroscopic properties of Yb-doped refractory sesquioxides: cubic Y2O3, Lu2O3 and monoclinic Gd2O3

Absorption and emission spectra are given for Yb³⁺-doped Y₂O₃, Lu₂O₃ and Gd₂O₃ at room temperature. Y₂O₃ and Lu₂O₃ as close cubic matrices, show Yb³⁺ similar spectra different of Yb³⁺ in Gd₂O₃ monoclinic structure. Here, we use a new method to study and optimize the main spectroscopic properties with only one concentration gradient sample. Finally, assignments of Yb³⁺ Stark levels and Raman vibrations in Y₂O₃, Lu₂O₃ and Gd₂O₃ single crystal are given.     

Al2O3量对2219车铝板上等离子喷涂Ni层组织和摩擦性能的影响

将Ni与Al₂O₃微米颗粒实施混合,再将其通过等离子喷涂方法沉积到2219铝合金表面,控制合适的喷涂工艺参数得到Al₂O₃/Ni复合涂层,实验测试研究Al₂O₃量对涂层组织和摩擦性能的影响。研究结果表明:与原始粉末相比,对涂层XRD测试发现形成强度很高的Ni衍射峰,Al₂O₃相发生了峰强度减小。在涂层内形成了灰色的Ni组织区,Al与Al₂O₃则呈现黑色的状态。逐渐提高Al₂O₃加入量后,形成了更多的黑色组织。涂层获得了比2219基体更高的硬度,相对于基体组织提高了3倍以上,提高Al₂O₃加入量后涂层硬度获得提升。涂层内含有的Al₂O₃比例提高后,涂层发生了摩擦系数和磨损率降低。当Al₂O₃含量继续增加后,形成较多氧化物,表现为氧化磨损。随着Al₂O₃含量的增加,氧化磨损程度表现出增加变化。     

RBS/channeling studies on the heteroepitaxially grown Y2O3 film on Si(100)

The heteroepitaxially grown yttrium oxide layer by an ionized cluster beam (ICB) on a Si(100) substrate was investigated by Rutherford backscattering spectrometry (RBS)/channeling. The channeling minimum value (χ_min) of the Y₂O₃ layer on Si(100) is 0.28, and this is the smallest value among those reported. From the channeling polar plots, it is found that Y₂O₃ film grown on Si(100) oriented with (110) direction and has a double domain structure. The 110 axis of Y₂O₃ layer is exactly parallel to the 100 axis of the Si substrate. It is also observed that the interface region of Y₂O₃ film has more crystalline defects than the surface region.     

Yttrium oxide film deposition by a Langmuir-Blodgett processing technique and its incorpiration into oxide scales by substrate oxidation

Thin films (about 10 nm) of Y₂O₃ have been deposited by a Langmuir-Blodgett processing technique onto a variety of substrates: type 304 stainless steel, low carbon steel, titanium, zirconium and silicon. The substrates were afterwards oxidized in air at 800, 1000 (304 steel), 400 (low C steel), 500 (Ti), 450 (Zr) and 1000 (Si) °C. The effects of the film on the oxide scale thickness and the interaction between Y₂O₃ and the oxide of the substrate have been studied by ion backscattering. In stainless steel, the Y₂O₃ film reduces the oxidation rate by orders of magnitude and Y is distributed throughout the oxide scalw (1–10 at.% level). In other substrates, the effect on oxidation rate was less pronounced, but changes in the visual appearance often took place. The Y₂O₃ incorporation varied for the different substrates, and Y₂O₃ remained as a surface film in the cases of Ti and Si. Such films exhibited good adherence and could not be removed by wiping. The potential use of metal oxide thin films for surface analysis standards and diffusion marker studies is discussed.     

Deposition of CeO2 films including areas with the different orientation and sharp border between them

Epitaxial films from one material, with sharp borders between contacting regions having different film orientation are grown on one surface of the substrate for the first time. The main reason for the deposition of thin ceria layers with mixed (001) and (111) orientations on a (1 02) sapphire substrate is determined. We suggest that this is related to the availability of surface defects which, in thin near-surface layers, deviate from stoichiometric composition. This in turn is connected with the loss of oxygen.

A technique for influencing CeO₂ film orientation is demonstrated. This involves specific preliminary processing of the substrate, and the selection of oxygen partial pressure during the deposition process.

High quality thin (30–50 nm) “protective” (001) CeO₂ epitaxial layers are prepared on (1 02) Al₂O₃. Structures comprising two epitaxial protective CeO₂ layers, orientations (001) and (111), are made on the base of (0001) and (1 02) sapphire substrates. The interface between the epitaxial layers is <1 000 nm.

Preliminary results using this method are described, and the possibility of creating a “bi-epitaxial” transition in thin YBa₂Cu₃O_7−x layers is explored.     

ZrO2(Y2O3)含量对双峰晶粒度分布Mo-12Si-8.5B-ZrO2(Y2O3)复合材料力学性能的影响

多相Mo-12Si-8.5B合金是一种很有应用前景的高温结构材料,为了同时提高Mo-12Si-8.5B合金的强度和韧性,提出了采用纳米ZrO₂(Y₂O₃)强韧化具有双峰晶粒度分布Mo-12Si-8.5B复合材料的方法。首先采用溶胶-凝胶和高温氢还原法制备了纳米Mo-ZrO₂(Y₂O₃)复合粉末,然后以纳米Mo-ZrO₂(Y₂O₃)粉末和微米Mo粉末为原材料,采用放电等离子烧结(SPS)技术制备了具有双峰晶粒度分布的Mo-12Si-8.5B-ZrO₂(Y₂O₃)复合材料。结果表明,随着ZrO₂(Y₂O₃)含量的增加,制备的Mo-ZrO₂(Y₂O₃)纳米粉末的粒度和烧结体相对致密度均逐渐减小,ZrO₂(Y₂O₃)含量小于2.5wt%时,烧结体的相对致密度均大于98.1%。当ZrO₂(Y₂O₃)含量为1.5wt%和2.5wt%时,复合材料具有较高的硬度(9.76~9.98 GPa),抗弯强度(672~678 MPa)和断裂韧性(12.68~12.82 MPa·m1/2)。Mo-12Si-8.5B-ZrO₂(Y₂O₃)复合材料中Mo晶粒细化、粗细Mo晶粒的晶界强化和纳米ZrO₂(Y₂O₃)颗粒第二相强化是提高硬度和抗弯强度主要原因;复合材料中粗晶粒Mo和纳米ZrO₂(Y₂O₃)有助于断裂韧性的提高,材料的增韧机制主要是裂纹偏转和裂纹桥接。      

Y2O3对钛基激光熔覆层组织及性能的影响

针对Ti811钛合金硬度低、耐磨性差的问题,以TC4粉、Ni45A粉和Y₂O₃粉为原料,采用同轴送粉激光熔覆技术在Ti811钛合金表面进行了激光熔覆制备耐磨复合涂层的实验,分析了熔覆层的组织和相组成,测试了熔覆层的显微硬度和摩擦磨损等力学性能。研究表明:复合涂层组织由枝晶TiC、依附生长于枝晶TiC表面的纳米颗粒TiC、生长于基体表面的等轴球形（近球形）TiC、金属间化合物Ti₂Ni、增强相TiB、TiB₂及基体α-Ti组成,所有生成相呈均匀弥散分布状态;涂层中等轴球形（近球形）TiC和Y₂O₃构成了复合相结构,经二维点阵错配度计算表明,Y₂O₃的（111）晶面与TiC的（110）晶面的二维点阵错配度δ=6.54%,因此Y₂O₃可作为TiC的有效异质形核核心细化晶粒;涂层的显微硬度处于HV_0.5 655~700之间,较Ti811基材提高了约1.6~1.8倍;涂层的磨损机制主要为磨粒磨损,摩擦磨损性能较基材显著提升。      

Low-temperature ionic conductivity of the solid solution in the system ZrO2–Y2O3–Yb2O3

Compositional dependence of ionic conductivity in the system ZrO₂–Y₂O₃–Yb₂O₃ was investigated in the temperature range 573–873 K using the complex impedance technique. It was shown that the conductivity decreases with increasing concentration of Yb₂O₃ in the system ZrO₂–Y₂O₃–Yb₂O₃. Analyzing the experimental data according to the classic Arrhenius equation showed that such an experimental phenomenon can be attributed to the tighter association between Yb³⁺ and oxygen vacancy, compared with that between Y³⁺ and oxygen vacancy, which hinders the migration of oxygen vacancy in the materials.     

Structural and optical properties of pulsed laser deposited V2O5 thin films

Pulsed laser deposited nanocrystalline V₂O₅ thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and optical spectroscopy. The films were deposited on amorphous glass substrates, keeping the O₂ partial pressure at 13.33 Pa and the substrate temperature at 220 °C. The characteristics of the films were changed by varying the laser fluence and repetition rate. XRD revealed that films are nanocrystalline with an orthorhombic structure. XPS shows the sub-stoichiometry of the films, that generally relies on the fact that during the formation process of V₂O₅ films, lower valence oxides are also created. From the HRTEM images, we observed the size evolution and distribution characteristics of the clusters in the function of the laser fluence. From the spectral transmittance we determined the absorption edge using the Tauc plot. Calculation of the Bohr radius for V₂O₅ is also reported.     

温度控制织构金属基带上YBCO外延薄膜生长及缺陷研究

采用直流溅射法在Y₂O₃/YSZ/CeO₂(YYC)缓冲层的织构NiW基带上, 通过基片温度调制YBa₂Cu₃O_7-δ(YBCO)外延薄膜生长。X射线衍射仪(XRD)表征显示, 基片温度强烈地影响YBCO薄膜的外延生长: 在较低的基片温度下薄膜趋于a轴取向生长, 随基片温度升高薄膜逐渐变为纯c轴取向生长。由于a轴晶粒引起的大角度晶界会阻碍超导电流在a-b面内的传输, 因此YBCO薄膜的微观结构和超导电性能随温度升高而得到改善, 但是随着基片温度继续升高, 基带的氧化程度加剧, YBCO与缓冲层间发生界面反应, 从而导致薄膜质量衰退。本