化学溶液沉积制备涂层导体Eu0.3Ce0.7O1.85-x单一缓冲层

采用高分子辅助化学溶液沉积(PACSD)方法,在双轴织构的NiW(200)合金基底上沉积了厚度大于160 nm的Eu0.3Ce0.701.85-x(ECO)单一缓冲层.制得的ECO缓冲层双轴织构良好,表面平整、无裂纹.同时,Eu的掺杂提高了CeO2单一缓冲层薄膜的临界厚度.在沉积了ECO缓冲层的NiW基带上外延生长的YBCO薄膜,超导零电阻转变温度Tc0=86K,临界电流密度达到Jc(O T,77 K)=0.4 MA/cm2.本研究提供了一种操作简单、成本低廉、性能优良的制备涂层导体单一缓冲层的方法.     

Preparation of Gd_(0.3)Ce_(0.7)O_(1.85-x) Single Buffer Layer for Coated Conductor Using a Novel-PACSD Method

To increase the critical thickness of CeO2 single buffer layer, the polymer assisted chemical solution deposition (PACSD) approach has been adopted to prepare a single buffer layer of Gd0.3Ce0.7O1.85-x (GCO) on bi-axially textured Ni-5%W alloy substrate, and the influences of different annealing temperatures on texture and microstructure of the buffer layer has also been studied in this paper. The results demonstrate that a well textured, dense and smooth GCO single buffer layer with thickness of 180 nm has...     

Fabrication of long-length ion beam-assisted deposited MgO templates for YBCO-coated conductors

The biaxially textured ion beam-assisted deposited(IBAD)-MgO templates were successfully prepared on polycrystalline Hastelloy metal substrate with reel-to-reel system for YB2Cu3O7-d(YBCO)-coated conductors.By the solution deposition planarization technique,amorphous Y2O3films were coated on untreated Hastelloy substrate as the bed layer to obtain smooth,dense,and crack-free surface for subsequent IBAD-MgO deposition.The 50 m long IBAD-MgO and homo-epitaxial(epi)-MgO buffer layers deposited on Y2O3films exhibit excellent crystallographic consistency along the scope with full width half maximum(FWHM)values of(110)DU and(200)Dx in the range of 5.5°–6.0°and3.0°–3.5°,respectively.To match the lattice constant of YBCO material,LaMnO3cap layer was fabricated on IBAD-MgO templates by radio frequency(rf)magnetron sputtering with the FWHM values of in-plane and out-ofplane of 6.8°and 3.7°,respectively,indicating excellent biaxial texture.     

织构金属衬底上CSD-SrTiO3薄膜的制备

涂层导体是发展77 K液氮温区强磁场下电力应用的实用化关键材料。由于缓冲层层数增加会导致控制生长、微观组织和界面结构的难度增大,所以简化缓冲层结构对涂层导体制备工艺的简化和成本的降低非常重要。本研究探索了低成本的化学溶液沉积(CSD)技术制备SrTiO_3(STO)缓冲层过程中前驱液热分解行为以及薄膜制备工艺路线对薄膜外延生长的影响,通过选取恰当的前驱液以及引入籽晶层沉积的方法最终获得了具有良好c轴织构且表面光滑的STO薄膜。     

Behavior of oxygen diffusion in buffer layers for coated conductors

We have evaluated the effect of annealing in oxygen atmosphere on the structure, texture and phase transformation of LZO films deposited on YSZ (yttria-stabilized zirconia) (0 0 l) single crystal substrates and textured NiW substrates by metal-organic deposition (MOD) method. The results show that the structure stability of the LZO films is heavily dependent on the oxygen partial pressure in annealing process. Then we have in details studied the behavior of oxygen diffusion in three kinds of buffer layer architectures on NiW substrates by varying the temperature, oxygen partial pressure and dwelling time in the annealing process. The oxygen diffusion within buffer layers leads to the oxidation of substrate, and even the texture and structure of buffer layers are destroyed with the increase of the thickness of the oxides layer related to NiW substrate. It reveals that the relative volume of oxides related to NiW substrate increases exponentially with the annealing temperature, and increases linearly with the annealing time at logarithmic scale. The relative intensity of texture peaks of buffer layers decreases and even disappears with the increase of the oxygen partial pressure in annealing process because of the acceleration of the oxidation reaction of substrate. The influence of annealing temperature, oxygen partial pressure and dwelling time on the oxygen diffusion is related to the intrinsic oxygen diffusion coefficient of buffer layers materials. Compared with the increase of oxygen partial pressure, the elongation of dwelling time shows a less effect on the oxidation rate of NiW substrate and a weak destruction of the texture of buffer layers. Except choosing the oxide materials with small oxygen diffusion coefficient as buffer layers in coated conductors, the degree of oxidation about NiW substrate could be greatly controlled and it would result in the less destruction of texture and structure of buffer layers by adjusting the annealing temperature, oxygen partial pressure and dwelling time in the process of YBCO deposition.     

Preparation of YBCO Coated Conductors on RABiTS Substrate with Advanced TFA-MOD Method

YBCO high temperature coated conductors are the most promising candidate for large scale superconducting transmission cables and fault current limiters. A modified TFA-MOD method was applied to prepare YBCO layer on Rolling Assisted Biaxially Textured Substrate (RABiTS) with textured Y 2 O 3 /YSZ/CeO 2 buffer layers, resulting in reduced time and cost of fabrication. By using Cu naphthenate instead of Cu(TFA) 2 , the pyrolysis time of the YBCO precursors was reduced significantly. YBCO films with thickness ...     

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 YBCO高温超导体有着广阔的应用前景，为改善其弱连接，通常要求强的c轴织构以提高临界电流密度值。通过RABiTS法可以在具有双轴织构的金属基底上外延生长出织构峰锐、组分单一的超导膜。为了减少晶格失配，通常需要在金属基体和超导层之间加入缓冲层。文章用2θθ扫描、扫描和ω扫描及极图法，对具有多层氧化物缓冲层的Ni/Y₂O₃/YSZ/CeO₂/YBCO 超导膜的织构进行了分析，表征了超导体由镍基带的立方织构经缓冲层的转动立方织构再到超导层的c轴织构的传递过程。     

Development of high strength and strongly cube textured Ni-4.5% W/Ni-15% Cr composite substrate for coated conductor application

The development of thin, mechanically stronger and highly cube textured substrates is of great technological importance for increasing the engineering current density of the coated conductors. Nickel is a suitable substrate for this in view of its ability to form strong cube texture after heavy rolling and annealing and its excellent oxidation resistance. However, nickel is very soft (yield strength ~40 MPa) and this limits the processing to thin tapes. The ferromagnetism of Ni is also undesirable for ac application of coated conductors in magnetic fields. In the present paper we report on the development of Ni-4.5 at.% W/Ni-15 at.% Cr composite substrates of 80 and 40 μm thickness with strong cube texture, high yield strength (~200 MPa) and reduced magnetisation losses. The strong cube texture was obtained through an optimised two-step recrystallisation annealing following heavy cold working. It was found that the presence of non-cube texture forming alloy (Ni-15% Cr) in the inner core of the composite had no adverse affect on the growth of cube textured grains on the surface (Ni-4.5% W) even at a low substrate thickness of 40 μm. A significant improvement in the texture/misorientation distribution was observed in the CeO₂ buffer layer deposited on the composite substrate.     

CSD-La3TaO7薄膜外延生长行为研究

涂层导体是实现氧化物高温超导材料在液氮温区强磁场应用的关键材料。在低成本的轧制辅助双轴织构/化学溶液沉积（RABiTS/CSD）路线中,缓冲层的良好外延生长是实现超导层织构生长以及高载流能力的前提,因此研究缓冲层外延生长行为就显得非常必要。本文探索了CSD技术制备La3TaO7（LTO）缓冲层过程中前驱液的热分解行为以及热处理工艺路线对薄膜取向生长的影响,通过选取恰当的LTO前驱液以及快速热处理升温的方法最终获得了良好c轴织构的LTO薄膜。     

化学溶液法制备的La_2Zr_2O_7缓冲层特性研究

利用XRD、电子背散射衍射分析(EBSD)和反射高能电子衍射(RHEED)等测试手段对化学溶液沉积技术制备的La2Zr2O7缓冲层的体织构和表面特性进行了研究。结果表明,在金属基带上,利用化学溶液沉积技术制备的La2Zr2O7缓冲层具有良好体织构和表面特性。     

Epitaxial deposition of NiO film on a cube-textured Ni substrate by metal-organic chemical vapor deposition

NiO films have been epitaxially grown by metal-organic chemical vapor deposition (MOCVD) on a bi-axially textured Ni substrate using Ni(thd)₂ as a precursor. The NiO film was deposited at 470°C for 10 min at a deposition pressure of 10 Torr and oxygen partial pressure of 0.91 Torr. SEM and AFM observations for the deposited NiO film showed a smooth and dense morphology. X-ray rocking curve and φ-scan showed that the NiO film has a bi-axial texture with a (100)<001> orientation. The out-of-plane and the in-plane deviations were measured to be 4.2° and 6~7° from the FWHM of (200) and (111) planes, respectively.     

Improvement of epitaxy and crystallinity in YBa2Cu3Oy thin films grown on silicon with double buffer of ECO/YSZ

A novel double buffer of Eu2CuO4 （ECO）/YSZ （yttrium-stabilized zirconia） was developed for growing YBa2Cu3Oy （YBCO） thin films on Si substrates. In these films, the severe reaction between Si and YBCO is blocked by the first YSZ layer, whereas, the degradation of crystallinity and superconductivity in the grown YBCO is greatly improved by the second ECO layer. Such an ECO material possesses a very stable 214-T＇ structure and excellent compatibilities with YBCO and YSZ. The result shows that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using the ECO/YSZ double buffer. The grown films are characterized by high-resolution X-ray diffraction, grazing incidence X-ray reflection, and transmission electron microscopy （TEM）, respectively. It is found that well defined interfaces are formed at YBCO/ECO/YSZ boundaries. No immediate layer could be seen. The defect density in all grown layers is kept at a lower level. The YBCO film surface turns out to be very smooth. These films have full superconducting transitions above 88 K and high current carrying capacity at 77 K. The successful growth of highly epitaxial YBCO thin films on silicon with ECO/YSZ buffer, demonstrate the advantages of such a double buffer structure.     

Fabrication of YBCO films on Ag substrate by TFA-MOD method

Biaxial aligned YBCO films have been successfully deposited on Ag { 110 } (110) textured polycrystalline substrates by metal-organic decomposition (MOD) method using Trifluoroacetate Salt (TFA). The influence of firing temperature and Ag surface defects on phase purity and texture, surface morphology of YBCO films was studied. Holding temperature at 900℃ for 30 rain benefits to improve orientation and connectivity of YBCO films. The surface of YBCO films deposited on unpolished Ag substrate has many holes and stripes, which are parallel to the rolling stripe on Ag substrates. To eliminate the rolling stripe on the Ag surface, Ag substrates were polished prior to films deposition. The film grown on polished Ag substrates has a smooth surface and good connectivity of grains without parallel stripes. The YBCO films have an onset of transition around 90K and critical current densities of 15000 A/cm^2.     

电泳沉积法在Ni-W基带上制备YBa_2Cu_3O_(7-δ)超导厚膜(英文)

研究La0.4Sr0.6TiO3(LSTO)缓冲层和YBa2Cu3O7-δ(YBCO)超导厚膜的低成本制备技术。采用X射线衍射分析LSTO和YBCO膜的晶体取向,利用标准四引线法分析LSTO薄膜的导电性能和YBCO厚膜的超导性能。首先采用金属有机沉积法(MOD)成功在Ni-W基带上制备取向较好、表面光滑致密的LSTO缓冲层;然后采用电泳沉积(EPD)技术制备YBCO超导厚膜。研究电泳沉积电压和沉积时间对YBCO涂层性能的影响。结果表明:138V下电泳沉积35 min所制备的YBCO涂层,临界电流密度可达600 A/cm2(0 T,77 K)。     

一种新型化学溶液沉积法制备涂层导体用RE2O3（RE=Y, Sm, Eu, Dy, Yb）缓冲层

用一种新的化学溶液沉积方法在双轴织构NiW (200)合金基底上制备了涂层导体用稀土氧化物RE2O3(RE=Y, Sm, Eu, Dy, Yb)缓冲层.分别利用X射线衍射,扫描电子显微镜,原子力显微镜对制得的RE2O3缓冲层的相结构、织构、表面形貌和平整度进行了检测.结果表明,RE2O3缓冲层具有较好的双轴织构,表面平整无裂纹.     

LZO covered Cu-based substrates

A Cu-based substrate has been made by electrodepositing a Ni layer on top of cube-textured Cu tape obtained by an alternating mechanical/thermal treatment. It could be found that the volume fraction of the cube texture component of Cu tapes increased with the annealing temperatures for an optimized rolling process. When the annealing temperature is at 800 °C, the sharpness of cube texture is best. In order to fabricate LZO films on the Cu-based substrate, a Ni layer was added on top of the Cu tape by electroplating. The thickness of Ni layer not only affects the texture sharpness of the substrate, but also affects its thermal stability of texture. A thickness of 15 μm was efficient to protect the Cu tapes. Fabricating well bi-axially textured LZO film on this bi-metallic substrate proves that this new Cu-based substrate is a good choice for coated conductor.     

金属基底上IBAD-YSZ缓冲层的生长机理

用离子束辅助沉积(IBAD)方法,变换辅助离子束的能量和束流密度,在Hastelloy基底上制备了钇稳定氧化锆(YSZ)薄膜,作为涂层导体的缓冲层。XRD的结果显示:在一定的离子能量和束流密度的范围内,能够制备出高质量双轴织构的(001)取向的YSZ缓冲层,随着辅助离子束能量和束流密度的增大,IBAD-YSZ的面外取向和面内织构都出现先变好又变坏的现象。文中用辅助离子束对薄膜破坏程度的各向异性对结果做了解释。     

MOD法在LaAlO3单晶上沉积La0.4Sr0.6CoO3导电缓冲层

用金属有机物沉积(MOD)法在LaAlO3(100)单晶基底上制备了立方钙钛矿型导电缓冲层La0.4Sr0.6CoO3(LaSrCoO)薄膜。根据热分析曲线确定前驱膜的热处理工艺,其中前驱膜的热分解温度为620～800℃,涂膜的结晶温度为825℃。由X射线衍射(XRD)分析可知,热处理后涂膜的主相是LaSrCoO,其择优取向为<100>;另外还有La2CO5和LaCoO3等杂相。由φ扫描和(100)极图可知,所制备的涂膜有较强双轴织构。用标准四引线法测量了涂膜的室温和低温电阻率,在77K时达到1.04×10-4?·m,实现了沉积导电缓冲层的目的。     

An approach to predict the solid film thickness possibly yielded from an alumina sol-gel liquid film

The Landau-Levich-Derjaguin (LLD) equation is widely used to predict the thickness of wet layer deposited on substrate by dip-coating. But it cannot effectively predict the solid film thickness yielded from the sol-gel liquid layer. Considering the solid content, the amount of solution sticking to the surface of substrate and the density of the sol-gel derived solids materials are the main factors determining the solid film thickness, a new approach capable of directly predicting what an oxide film thickness of a liquid layer on the substrate could yield without really sintering at high temperature was developed. It was found that the predicted and measured thicknesses for both compact and porous Al₂O₃ films were in good accordance. The approach uses very common testing techniques and does not concern the aspects such as solution composition, Newtonian or non-Newtonian fluid, withdrawal speed, viscosity, and liquid-vapor surface tension, etc. So the method is much timesaving and economical, and will be a good supplement for thickness determination techniques, especially under some circumstances where use of SEM, XRR, ellipsometer analyses are limited.     

钇钡铜氧超导厚膜的研究进展

YBa2Cu3O7-x(YBCO)涂层导体(也称第二代高温超导带材)在77 K下具有较高的不可逆场和本征载流能力,在强电领域有着广泛的应用。第2代高温超导带材是基于薄膜外延技术发展起来的实用超导材料,为使其尽快商业化,科学家们一直在不断探索研究YBCO的基础物性和成材机理。如何制备具有高临界电流密度的厚膜就成为当前YBCO高温超导涂层应用过程中亟待解决的关键问题。介绍了厚膜与临界电流之间的关系并综述了国际主流研究机构对YBCO厚膜的最新研究进展情况。