调制比对GDC/YSZ多层氧离子导体薄膜结构与电学性能的影响

采用反应射频磁控溅射技术在(0001)蓝宝石基片上制备了不同调制结构的(GDC/YSZ)12多层氧离子导体电解质薄膜。利用电子探针微区分析技术测得薄膜的摩尔质量比为m(Zr):m(Y)=5.73:1、m(Ce):m(Gd)=4.12:1;X射线衍射(XRD)与小角X射线反射(XRR)结果表明,GDC/YSZ调制比为5:1、2:1和1:2的样品(A1～A3)具有好的超晶格结构,而A4样品未形成超晶格结构;原子力显微镜形貌分析结果表明多层膜呈密集岛状生长形貌,与GDC、YSZ单层膜比较,多层膜生长岛尺寸减小,密度增大,表面粗糙度明显减小;电学性能测试与理论分析结果表明,界面缺陷使多层膜电导率提高,而GDC成分增多,则超晶格多层膜电导率增大。     

衬底温度对钇稳定氧化锆薄膜择优生长的影响

使用脉冲激光沉积(PLD)技术在Si(100)衬底上沉积钇稳定的氧化锆(YSZ)薄膜,用XRD分析薄膜的结晶取向,SEM和AFM观测薄膜表面形貌,研究了在200-650℃的不同衬底温度下薄膜的择优生长.结果表明:衬底温度较低的YSZ薄膜为非晶组织,衬底温度为300-500℃时YSZ晶粒以表面能低的(111)面首先择优生长,衬底温度超过550℃后晶粒活化能提高而使表面能较高的(100)晶粒择优生长.YSZ薄膜是典型的岛状三维生长模式,较高的衬底温度有利于原子在衬底表面迁移和重排结晶长大.同其它沉积技术相比,用PLD技术能在比较低的衬底温度下在Si(100)表面原位外延生长出较高质量的YSZ薄膜.     

不同沉积速率下微晶硅薄膜的生长行为研究

鉴于微晶硅薄膜在沉积过程中先经历一个非晶过渡层才开始晶化的生长特点,试图通过降低薄膜的沉积速率来延长沉积原子在薄膜生长表面的扩散时间,以达到促进晶粒生长的目的。研究结果表明,反应气体气流量的减小可以有效降低薄膜的沉积速率;随着沉积速率的降低,薄膜的表面粗糙度明显减小,且其平均晶粒尺寸有所增大,通过HRTEM甚至能观察到尺寸在10nm以上的晶粒,说明沉积速率的降低对沉积粒子在薄膜生长表面的扩散过程有较大影响;另外,薄膜的少子寿命随着沉积速率的降低逐渐增大,这与薄膜结晶程度和平均晶粒尺寸的变化趋势一致,可见微观结构对电学性能起着决定作用。     

多弧离子镀与磁控溅射共沉积TiN/TiCN多层膜的高温抗氧化性能

TiN/TiCN多层膜的高温抗氧化性研究对于扩大其应用领域具有重要作用,但目前鲜见相关报道。采用多弧离子镀与磁控溅射技术以不同调制周期在304不锈钢表面共沉积TiN/TiCN多层膜。采用XRD、XPS、倒置显微镜及高温氧化试验研究了多层膜的高温抗氧化行为。结果表明:TiN/TiCN多层膜表面光滑平整、均匀致密,薄膜主要为具有Ti-(C,N)键的fcc-TiN结构;随着调制周期的减小,TiN/TiCN多层膜生长取向发生转变,且具有(111)晶面生长织构;随着氧化温度的升高,多层膜的显微硬度逐渐降低,氧化增重速率不断增大,且在700℃之后变化速率较快,薄膜的开始氧化温度约为750℃;随着调制周期的减小,多层膜TiN与TiCN界面层数量增多,促使晶粒细化,提高了其致密性,还隔断了缺陷贯穿薄膜的连续性,显著降低了薄膜的孔隙率,致使O原子扩散困难,增强了薄膜的高温抗氧化性能。     

沉积温度对Gd掺杂CeO2电解质薄膜生长及电学特性的影响

采用反应射频磁控溅射技术,在非晶石英衬底上不同温度下制备了纳米多晶Gd掺杂CeO2(简称GDC)氧离子导体电解质薄膜,采用X射线衍射仪、原子力显微镜对薄膜物相、晶粒大小、生长形貌进行了表征,利用交流阻抗谱仪测试了GDC薄膜的电学性能.结果表明,GDC薄膜生长取向随沉积温度而变化:300-400℃时为强(111)织构生长,而500-600℃时薄膜趋于无规则生长;随着沉积温度的升高,薄膜的牛长形貌由同一取向的大棱形生长岛转变为密集球形小生长岛;GDC多晶薄膜的电导活化能约为1.3eV,接近于晶界电导活化能值,说明GDC交流阻抗主要源于晶界的贡献;晶界空间电荷效应导致GDC薄膜电导率随晶粒尺寸而变化,晶粒尺寸越小,电导率越大.     

掺硼对超纳米金刚石薄膜的影响

采用微波等离子体化学气相沉积(MPCVD)技术,利用氩气、甲烷、二氧化碳混合气体,制备出平均晶粒尺寸在7.480 nm左右,表面粗糙度在15.72 nm左右的高质量的超纳米金刚石薄膜;在此工艺基础上以硼烷作为掺杂气体,合成掺硼的金刚石薄膜.表征结果显示在一定的浓度范围内随着硼烷气体的通入,金刚石薄膜的晶粒尺寸及表面粗糙度增大、结晶性变好,不再具有超纳米金刚石膜的显微结构和表面形态;同时膜材的物相组成也发生改变,金刚石组份逐渐增多,并且膜层内出现了更明显的应力以及更好的导电性能.     

(Ce_(0.9)Gd_(0.1)O_(2-δ)/ZrO_2:8%(摩尔分数)Y_2O_3)_n超晶格电解质薄膜的制备与特性

采用脉冲激光沉积技术(PLD),在SrTiO_3(STO)单晶片上依次沉积钇稳定氧化锆(ZrO_2∶8%(摩尔分数)Y_2O_3,YSZ)和氧化钆掺杂的氧化铈(Ce_(0.9)Gd_(0.1)O_(2-δ),GDC)制备出5种不同调制周期数n(n=4,6,10,20,30)的(Ce_(0.9)Gd_(0.1)O_(2-δ)/ZrO_2:8%(摩尔分数)Y_2O_3)_n超晶格电解质薄膜。利用X射线衍射(XRD)、高分辨率透射电子显微镜(HR-TEM)和扫描电子显微镜(SEM),研究(GDC/YSZ)n超晶格电解质薄膜的形貌和晶体结构,发现薄膜表面颗粒生长致密、均匀,薄膜的界面处无元素扩散,外延生长状况良好,薄膜的结构优异。电化学测量研究表明,随着(GDC/YSZ)n超晶格电解质界面数的增加,其离子电导率相应增加,(GDC/YSZ)n=30超晶格电解质的离子电导率最大。     

近空间升华法制备PbI_2厚膜及其性质研究

采用近空间升华法在玻璃衬底上制备PbI2厚膜,研究了工艺参数对样品晶体结构、形貌和光致发光性质的影响。实验显示,沉积速率随着源温度的升高和沉积气压的下降而急剧增大。XRD谱表明PbI2膜为沿[001]晶向择优取向的六方多晶体,晶粒尺寸随沉积速率的增大而逐渐减小。同时,沉积速率增大还导致膜压应力变大,晶格常数减小,使（001）晶面衍射峰向大角度方向移动。SEM照片显示样品为（001）晶面堆积而成的片状晶粒结构,晶粒c轴与衬底平行。随着沉积速率的增大,晶粒有序性和膜致密度下降,同时（001）晶面上由于六方中心亚晶粒的出现而导致表面粗糙度大幅增大。样品的PL发光谱显示了本征发射特征,发光锋随沉积速率的增大向长波方向移动,同时峰位展宽,强度减弱。     

用AFM研究硅基上沉积铜膜生长过程

室温下,利用磁控溅射在P型Si(111)衬底上沉积了铜(Cu)膜.用原子力显微镜(AFM)对不同沉积时间制备的Cu膜形貌进行了观测,研究了磁控溅射沉积Cu膜时膜在硅衬底上成核和生长方式.Cu膜在Si衬底生长时,Cu的临界核以Volmer-Weber模式生长.溅射时,核长大增高为岛状,岛与岛相互连接构成岛的通道,最后形成连续膜.随着沉积的进行,Cu膜表面粗糙度由于晶粒凝聚和合并而增大.当形成连续致密的、具有一定晶向的Cu膜时,粗糙度反而减小.     

离子束溅射Si／Ge多层膜的界面结构研究

采用离子束溅射技术，在玻璃衬底上制备了不同周期数的Si／Ge多层膜样品。通过Raman光谱和X射线小角衍射对薄膜进行了表征和分析，发现随着生长周期数的增加，层与层之间的互扩散效应逐渐减弱，界面结构逐渐清晰，生长周期为25的样品界面最平整。     

Preparation of YSZ/YDC and YSZ/GDC composite electrolytes by the tape casting and sol-gel dip-drawing coating method for low-temperature SOFC

The composite electrolytes for low-temperature solid oxide fuel cells were fabricated via coating the YSZ sol on tape-casted substrates of yttria doped ceria (YDC) and gadolinia doped ceria (GDC). The doped ceria substrates with 98% of relative density were prepared by the tape-casting method followed by the sintering at 1,500°C for 2 hours. The YSZ polymeric sol for dip-drawing coating was synthesized by the partial hydrolysis of Zr-n-butoxide. The optimum dip-drawing coating rate for obtaining pinhole and crack free YSZ film was 2 cm/min using YSZ polymeric sol with 1.13 mol/ of concentration. After 10 times coating on ceria substrates with YSZ followed by the heat-treatment at 1,400°C for 2 hours, the fully densified YSZ film with 2.0 m of thickness without pores, cracks, or chemical reactions could be obtained. The results of single cell tests shows that YSZ layer coated doped ceria composite electrolyte prepared by the sol-gel dip-drawing method has an superior single cell performance to YSZ electrolyte without dissociation of ceria substrate.     

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

Nano-Micro Letters - A Gd-doped ceria (GDC) buffer layer is required between a conventional yttria-stabilized zirconia (YSZ) electrolyte and a La-Sr-Co-Fe-O3 (LSCF) cathode to prevent their...     

Oxidation and reduction behavior of Ni and NiO layers sputter deposited onto yttrium-stabilized zirconia single crystals

Thin single-crystal yttrium-stabilized zirconia (YSZ) substrate was prepared by indentation fracture and mechanical polishing. The specimen was analyzed in detail by transmission electron microscopy (TEM). The (110) edge surface was faceted, in contrast to the smooth (001) edge surface, and the facet surfaces were identified as {111}-type planes. Good cross-sectional TEM specimens comprised of crystalline Ni and NiO layers deposited on YSZ edge surface could be prepared by sputtering of a Ni support grid using Ar⁺ ion milling and subsequent re-deposiotion on the smooth (001) fracture surface of the YSZ specimen. The epitaxial growth of a pure Ni layer on the YSZ edge planes occurred during ion milling in vacuum. However, subsequent ion milling of the specimen after exposure in air for several minutes resulted in the formation of a NiO layer on top of the first Ni layer. Reduction of the NiO layer was confirmed by electron energy-loss spectroscopy after annealing at 973 K in a vacuum of 1.2 × 10⁻⁵ Pa. This Ni layer was re-oxidized upon annealing in air at 1073 K for 1 h. The deposition behavior of the Ni and NiO layers was discussed on the basis of the surface oxidation of Ni layer.     

Epitaxial growth of CeO2/yttria-stabilized ZrO2 double layer films on biaxially textured Ni tape via electrostatic spray assisted vapour deposition

Epitaxial growth of CeO₂ and yttria-stabilized ZrO₂ (YSZ) double layer films has been successfully carried out on biaxially textured nickel substrates at a temperature between 400 and 600 °C using electrostatic spray assisted vapour deposition method. The structure of the double layer was characterized by X-ray diffraction and scanning electron microscopy. The results show that highly oriented CeO₂/YSZ double buffer films were formed epitaxially onto biaxially textured Ni substrates. The orientation relationships between YSZ layer and Ni substrate are 001_YSZ//001_Ni and 110_YSZ//100_Ni, while the orientation relationships between CeO₂ and YSZ are 001_CeO2//001_YSZ and 100_CeO2//100_YSZ.     

NiCrAl/YSZ/NiCrAl-B.e复合涂层对α+β型高温钛合金燃烧产物的影响

通过摩擦氧浓度方法点燃涂覆NiCrAl/YSZ/NiCrAl-B.e复合涂层的TC11钛合金,采用XRD,SEM,EDS及EPMA等微观表征方法对其燃烧产物进行分析,进而探讨复合涂层对燃烧行为的影响机理。结果表明:燃烧试样的基体从中心孔沿径向往外呈分区组织演变特征,中心孔处的钛合金基体是着火源;当燃烧程度较低时,YSZ中间层对钛合金燃烧行为的影响较小;当剧烈燃烧时,YSZ中间层通过分解反应而在钛合金熔体中大量溶解,为钛合金熔体提供了O和Zr,加速了Ti与O的快速结合,同时ZrTiO_4燃烧产物的阻氧能力比TiO_2差,从而大大促进了钛合金的扩展燃烧。     

Convection–diffusion derived gradient films on porous substrates and their microstructural characteristics

By virtue of the convection–diffusion effect of solution in porous solid media, an alumina substrate-supported electrolyte film (YSZ) with gradient microstructure has been successfully fabricated for the first time and structurally characterized by SEM and XRD–ADA (angular dispersion analysis). This novel fabrication technique is simple, controllable, economical and potentially applicable to fabricating electrode-supported gradient electrolyte films for SOFCs. The so-prepared YSZ-film/substrate structures are featured with a dense YSZ film of ∼10 μm, a uniform filling layer of ∼50 μm just beneath the interface and a successive diffuse layer stretching as deep as ∼250 μm within the porous substrate matrix.     

燃气热循环下7YSZ热障涂层的微结构演变与阻抗谱特征

在1250℃燃气热循环条件下,测试热障涂层抗冷热冲击性能,以模拟发动机叶片的启动升温与关闭降温循环过程。采用电化学阻抗谱测试和扫描电镜(SEM)系统研究热循环过程中热生长氧化物(TGO)生长与YSZ陶瓷层微结构演变。结果表明:随着热循环次数增加,热障涂层内TGO不断生长变厚,在中频阶段的阻抗谱响应越来越显著。YSZ陶瓷层内部经历了微裂纹的萌生与扩展两个阶段。经过100次热循环后的YSZ层表现出与喷涂态涂层相似的阻抗特征,表明高温下烧结会使YSZ层产生的微裂纹在短时间内愈合。但经过300次热循环后的YSZ层表现出与喷涂态完全不同的阻抗谱,并随热循环次数增加,YSZ颗粒间隙阻抗值不断增加,表明YSZ内层产生了不可愈合的微裂纹,是导致YSZ层最终失效的主要因素。     

Microstructure,texture, and crystallography in Ni–GDC and Co–GDC porous cermets obtained from directionally solidified eutectic ceramics

Lamellar NiO–GDC (Gadolinium-doped Ceria) and CoO–GDC directionally solidified eutectic ceramics (DSECs) were produced by the laser floating-zone technique and subjected to reduction in order to obtain porous cermets of Ni–GDC and Co–GDC, which have potential applications as anodes in solid oxide fuel cells (SOFC). The reduction of these DSECs into porous cermets was studied at 650 °C in NiO–GDC and at 500 and 700 °C in CoO–GDC, all of them processed with similar reduction kinetics. In comparison to similar Ni–YSZ and Co–YSZ lamellar cermets previously studied, no sharp reduction front was observed. The interface between the reduced and nonreduced zones is broader, with pores homogenously distributed in wide areas. Afterwards, the microstructure, texture, and crystallography of the samples were studied by electron microscopy as well as by electron and X-ray diffraction when completely reduced. The single crystal NiO and CoO lamellae transformed into porous polycrystalline metallic lamellae. Moreover, microscopy observations revealed a porous nanostructure of Co particles obtained by reduction at low temperatures (500 °C). Many of the Co and Ni particles seemed to have roughly maintained the previous crystallographic orientation with respect to the GDC phase, although the disorder of the crystallographic orientation increased significantly. In addition, a significant amount of the Ni particles reoriented to form an epitaxial interface with the (100)–GDC surface.     

Characterization of electrolyte films deposited by using RF magnetron sputtering a 20 mol% gadolinia-doped ceria target

20 mol% Gd-doped ceria (20GDC) electrolyte films on poly-crystalline Al₂O₃ substrates were prepared by radio frequency (RF) magnetron sputtering from a 20GDC oxide target, which was made by the processes of colloidal dispersion-pressure casting-sintering. Material characteristics of the 20GDC oxide target and the deposited films before and after annealed at 900 °C for 2 h were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and conductivity measurements. Crack-free and dense 20GDC electrolyte films were observed by the deposition conditions of 200 W (RF power). Homogeneity tests revealed the chemical compositions (Ce and Gd) were uniformly distributed through the bulk of the target and the deposited films. 20GDC film with a comparable conductivity of 1.00 × 10^− 3 S/cm at 650 °C is higher than that of bulk yttria-stabilized zirconia (YSZ), but smaller than that of bulk GDCs (10GDC and 20 GDC). Sputtered-GDC films in this study can be also suggested to be used as the electrolyte films for solid oxide fuel cells (SOFCs) systems as compared to the well-known YSZ.     

Ceramic nanopatterned surfaces to explore the effects of nanotopography on cell attachment

Surfaces with ordered, nanopatterned roughness have demonstrated considerable promise in directing cell morphology, migration, proliferation, and gene expression. However, further investigation of these phenomena has been limited by the lack of simple, inexpensive methods of nanofabrication. Here, we report a facile, low-cost nanofabrication approach based on self-assembly of a thin-film of gadolinium-doped ceria on yttria-stabilized zirconia substrates (GDC/YSZ). This approach yields three distinct, randomly-oriented nanofeatures of variable dimensions, similar to those produced via polymer demixing, which can be reproducibly fabricated over tens to hundreds of microns. As a proof-of-concept, we examined the response of SK-N-SH neuroblastoma cells to features produced by this system, and observed significant changes in cell spreading, circularity, and cytoskeletal protein distribution. Additionally, we show that these features can be imprinted into commonly used rigid hydrogel biomaterials, demonstrating the potential broad applicability of this approach. Thus, GDC/YSZ substrates offer an efficient, economical alternative to lithographic methods for investigating cell response to randomly-oriented nanotopographical features.