Preparation of YSZ films by magnetron sputtering for anode-supported SOFC中文翻译

Preparation of YSZ films by magnetron sputtering for anode-supported SOFC

磁控溅射制备阳极支撑固体氧化物燃料电池的YSZ薄膜

Haiqian Wang a,,Weijie Ji a, Lei Zhang a, Yunhui Gong a, Bin Xie a, Yousong Jiang b, Yizhou Song b

Hefei National Laboratory for Physical Sciences at the Microscale, and USTC-Shincron Joint Lab., University of Science and Technology of China, PR China Shincron Co. Ltd., 3-5 Minatomirai, 4 Chome, Nishi-ku, Yokohama, Japan

abstract

YSZ films for anode-supported SOFCs were prepared by reactive sputtering method. It was found that the surface morphology of anode substrate has a very important effect on the quality of sputtered films. By applying an anode functional layer and making the anode surface smooth, dense and uniform YSZ films of 10 μm in thickness were successfully fabricated. The sintering behaviors of the sputtered YSZ films were also discussed. It is suggested that the optimized densification condition for the deposited YSZ films is sintering at 1250 °C for 4 h. Single cells with sputtered YSZ film as electrolyte and LSM–YSZ as active cathode materials were tested. 1.08 V open circuit voltage and a 700 mW/cm2maximum power density were achieved at 750 °C by using humidified H2as fuel and air as oxidant. Tape cast

YSZ薄膜的阳极支撑固体氧化物燃料电池是由反应溅射的方法制备的。结果表明阳极衬底的表面形态对一个溅射薄膜的质量有着非常重要的影响。通过应用一个阳极功能层和使阳极表面光滑、致密、均匀薄膜厚度为10μm的YSZ成功制作。溅射YSZ薄膜的烧结行为也进行了讨论。我们建议优化YSZ薄膜沉积在烧结致密化条件为在1250°C温度下4小时，溅射YSZ膜的单电池作为电解质和作为活性阴极材料的LSM-YSZ进行了测试。1.08 V开路电压和700 mW / cm2最大功率密度，在750°C实现通过使用湿氢气作为燃料和空气作为氧化剂。

Keywords: YSZ Sputtering Anode Sintering SOFC

关键词：YSZ 溅射阳极沉积固体氧化物燃料电池

1.Introduction介绍

Reducing the operation temperature of a solid oxide fuel cell (SOFC) system to the intermediate temperature range (600–800 °C) is considered as an effective way to reduce its cost and increase its reliability and stability; therefore, may promote the SOFC technology to commercialization [1]. However, at lower temperatures, the ionic conductance of electrolyte materials becomes a matter of concern. A widely accepted criterion for an electrolyte is that the area specific resistance (ASR) should be smaller than 0.15 Ω cm2 at the operation temperature [2]. In order to meet this criterion, one needs either to use materials with higher ionic conductivity, or to reduce the thickness of the electrolyte. Reducing the electrolyte thickness is a favorite way for practical applications, because cheap, reliable and mature electrolyte materials, say yttria-stabilized zirconia (YSZ), can be used. In order to make the YSZ electrolyte material to be used in the intermediate temperature range, 10-μm-thick or even thinner YSZ

films are preferred.YSZ films can be fabricated by a number of processes. Conventional ceramic processing techniques such as slurry coating, screen printing, and tape casting have been used to prepare YSZ electrolyte films for anode-supported SOFCs [3]. Magnetron sputtering is a well commercialized technique for thin film industry. The advantages of preparing YSZ films by magnetron sputtering include: dense and thin YSZ films can be prepared, the processing temperature is low, large area and uniform films can be produced with mass production capability, and the reproducibility of the films are good [3,4]. Sputtering is also a clean process; there are no toxic gas and liquid emissions.It has been reported that dense and gastight YSZ films were prepared by magnetron sputtering on Ni–YSZ substrates; single cell tests indicated that open circuit voltages were close to the theoretical values, and reasonable power densities can be obtained [5,6]. However, there are still challenges for this technique to be applied for practicable SOFC applications. For example, it is necessary to deposit dense and gastight electrolyte films on ceramic substrates,which usually have very rough surfaces [5,6]. The sintering behaviorsof the sputtered YSZ films are also quite different from those preparedby ceramic powder processes. Therefore, understanding the effects ofanode substrates and sintering temperatures on the sputtered YSZfilms is very important.In the present work, YSZ films of 10 μm in thickness were

fabricated by reactive magnetron sputtering on NiO–YSZ anodesubstrates. The effects of anode surface morphology and

sinteringtemperature on the microstructures and properties of the YSZ filmswere studied and discussed.

降低操作温度的固体氧化物燃料电池(SOFC)系统中间温度范围(600~800°C)被认为是用来降低成本和提高

其可靠性和稳定性的一个有效的方法,因此,可以促进固体氧化物燃料电池技术的商业化[1]。然而,在较低的温度下,电解质材料的离子电导成为关注的问题。对于电解质而言，一个被广泛接受的标准是面积比电阻(ASR) 在操作温度下，应小于0.15Ωcm2 [2]。为了满足这一标准,要么需要使用高离子电导率的材料,要么降低电解质的厚度。减少电解质厚度是一个人们在实际应用中最喜欢的方式,因为可以使用便宜,可靠和成熟的电解质材料,例如氧化钇稳定氧化锆(YSZ)。为了使YSZ电解质材料在中间温度范围使用,10μm厚的甚至薄YSZ薄膜成为首选。YSZ薄膜可以被许多工序制作出来。传统陶瓷加工技术,如浆涂料,丝网印刷,和流延成型用来制备用作阳极支撑固体氧化物燃料电池YSZ电解质薄膜[3]。薄膜的磁控溅射是商业化的技术行业。通过磁控溅射制备YSZ薄膜的优点包括:致密和薄的YSZ薄膜可以准备,加工温度低,面积大和均匀的薄膜可以具有大规模生产能力以及薄膜的再现性好[3,4]。溅射也是一个干净的过程;没有有毒气体和液体的排放。据报道,密集,气密性好的YSZ薄膜是由磁控溅射Ni-YSZ基质制备出来的;单电池测试表明,开路电压接近理论值,可以获得合理的功率密度[5,6]。然而,这项技术适用的可行的固体氧化物燃料电池的应用仍然有挑战。例如,需要在陶瓷衬底上沉积密集,气密性好的电解质膜,它通常有很粗糙表面[5,6]。溅射的烧结行为YSZ薄膜也很不同于由陶瓷粉的过程。因此,了解阳极衬底和烧结温度的影响在溅射的YSZ的薄膜是非常重要的。在目前的工作,10μm YSZ薄膜的厚度是通过反应磁控溅射NiO-YSZ阳极衬底制作的。阳极表面形态的影响,烧结温度对YSZ薄膜的微观结构和性能进行了研究和讨论。

2. Experimental实验

2.1. Anode preparation阳极制备

The anode preparation processes include spraying the anode functional layer (AFL) first, followed by tape casting of the anode slurry, and then the obtained green tapes were sintered.TheAFL was prepared by suspension spray method. NiO (Baker,USA) and 8YSZ (Tosh, TZ-8Y, Japan) powders in a weight ratio of 55:45 were mixed with ethanol and butanone as solvents, triethanolamine as dispersant, poly-vinyl-butyl as organic binder and polyethylene glycol as plasticizer. After ball milled for 24 h, the slurry was sprayed on a polythene membrane.The anode substrate layer was prepared by tape casting

https://www.sodocs.net/doc/bf2684210.html,mercialNiO and 8YSZ powders were mixed in a weight ratio of 55:45. Starch was added as pore former in a weight ratio of 10% of thetotal solid contents. The powders were mixed with ethanol and butanone as solvents, triethanolamine as dispersant, poly-vinyl-butyl as organic binder and polyethylene glycol as plasticizer, and then ball milled for 24 h to form homogeneous slurry. The de-aired slurry was cast on the dry AFL green layer. After being dried, the green tapes were cut into

50×50 mm2 pieces and sintered at 1400 °C for 5 h. After being sintered all the products were 35×35×0.5 mm3 in dimensions.

The porosity of the anode substrates was 23% before reduction. The anode surface modified with an AFL has a smooth surface morphology. This is because the AFL was directly in contact with the polythene membrane during the spraying and tape casting processes. Fine particles in the spraying slurry sedimented to the polythene membrane and made the AFL surface much smoother. As will be discussed later, a smooth surface is very critical for the sputtering of YSZ films.For comparison purposes, anode substrates without any AFL layer were also prepared intermediately on a polythene membrane with tape casting method by using the same tape casting slurry.

阳极制备过程包括首先喷涂阳极功能层(AFL),紧随其后的是阳极泥浆的流延成型,然后获得未处理的带卷用来烧结。喷涂阳极功能层是由悬浮喷射法。NiO(Baker, USA)和8YSZ(Tosh, TZ-8Y, Japan)粉以乙醇和丁酮为溶剂、三乙醇胺作为分散剂,聚乙烯异丁醚有机粘结剂和聚乙二醇增塑剂，比例为55:45的重量比混合。球磨24 h后,泥浆喷洒在聚乙烯膜。阳极基体层是由流延成型。商业NiO和8YSZ粉末混合比例为55:45的重量比。淀粉添加孔前的重量比10%的总固体含量。粉末的混合乙醇和丁酮作为溶剂，三乙醇胺作为分散剂,聚乙烯异丁醚有机粘结剂和聚乙二醇作为塑化剂,然后球磨24 h形成均匀的浆。除气泥浆出现阳极功能层未处理层。干后,未处理的带卷是切成50×50平方毫米块和在1400°C下，烧结5 h。烧结后的产品都是35×35×0.5 mm3大小的。阳极基质的孔隙度与之前相比减少了23%。阳极功能层的阳极表面改性有光滑的表面形态。这是因为阳极功能层直接接触聚乙烯膜在喷涂和流延成型过程。微粒在喷洒泥浆沉淀阳极功能层的聚乙烯膜表面

更为顺畅。这些会在稍后讨论,表面光滑YSZ薄膜的溅射很关键。作为比较,阳极衬底没有任何阳极功能层也准备在中间在聚乙烯膜用流延成型方法通过使用相同的流延成型泥浆。

2.2. YSZ films preparation by reactive magnetron sputtering反应磁控溅射制备YSZ薄膜

A mid-frequency reactive magnetron sputtering system (ASC-800,Shincron Co. Ltd.) was used to deposit YSZ films. The sputtering power was kept at 3 kW. The sputtering targets were metallic Zr–Y composite with a Zr:Y weight ratio of 92:8. The base vacuum level was 2×10-4Pa. The O2 and Ar flow rates were 150 and 50 sccm, respectively. The total pressure was 0.17 Pa during deposition. The films were deposited upon 32×32 mm2 NiO–YSZ anode substrates with 0.5 mm in thickness. The deposition rate was 0.5 μm/h. The starting substrate temperature was room temperature. No active heating or cooling was applied to the substrates during the deposition processes. The substrate temperature rises resulting from the bombardment of the energetic sputtering species were detected by an infrared temperature detector, and the maximum temperature was below 200 °C. The crystallization and microstructure of the YSZ films were mainly examined by an X-ray diffractometer (XRD) (MXPAHF) and a scanning electron microscopy (SEM) (JSM-6700F, JEOL). Fluorite type cubic phase structures of the as-deposited and sintered YSZ films were confirmed with XRD and Raman (RAMANLOG 6, SPEX) analysis. The Y2O3 molar ratio in the films was ～9 mol%, which was determined with X-ray fluorescence spectroscopy (XRF) (XRF-1800, SHIMADZU). The composition of the deposited YSZ films deviated from that of the sputtering targets. This may be caused of theresputtering processes during the deposition [7].

中频反应磁控溅射系统(asc - 800,Shincron有限公司)被用来沉积YSZ薄膜。溅射功率保持在3 kW。溅射靶金属Zr-Y复合材料Zr:Y 92:8的重量比。本底真空度是2×10?4Pa。O2和Ar流率分别是150和50 sccm。在沉积时，总压强是0.17 Pa。薄膜沉积在32×32平方毫米NiO-YSZ阳极基上，厚度为0.5毫米。沉积速率为0.5μm / h。起始衬底温度是室温。在应用于基质沉积过程中没有主动加热或冷却。轰击的高能溅射导致衬底温度的升高，轰击的高能溅射种类可以被红外线温度检测器检测,并且最高温度是低于200°C。YSZ薄膜的晶体及显微组织主要是由X射线衍射仪(XRD)(MXPAHF) 和扫描电镜(SEM)( JSM-6700F, JEOL)检查。沉积和烧结态的YSZ 薄膜用XRD和拉曼(RAMANLOG 6, SPEX)分析证实了萤石型立方相结构。Y2O3薄膜摩尔比为9mol%，它取决于x射线荧光光谱(光谱仪)(光谱仪- 1800,日本岛津公司)。YSZ薄膜沉积的成分偏离溅射的目标。这可能是沉积过程中的反溅射造成的[7]。

2.3. Impedance measurement and single cell testing阻抗测量和单电池检测

The electrochemical impedance spectroscopy of YSZ film was measured with a Solartron 1260 meter in a frequency range of 1–107Hz with AC signal amplitude of 100 mV. Single cells were obtained by adding a 20-μm-thick LSM–YSZ composite cathode functional layer (CFL) and a 60-μm-thick LSM cathode current collecting layer on the sputtered YSZ films by using the screen printing method. The CFL and current collecting layer were co-sintered at 1150 °C for 3 h. The single cell performances were examined with the two-electrode four-wire setup. Ag paste was painted on the cathode and anode sides, respectively. Ag mesh was pressed against the Ag paste layer for better current collection. NiO–YSZ anode was reduced at 700 °C under H2 atmosphere for 2 h. After reduction, the performance of the cells was evaluated with a DC electronic load (N3300, Agilent) from 700 to

800 °C with humidified H2 (2–3% H2O) as fuel and air as oxidant.

YSZ薄膜的电化学阻抗谱由Solartron1260——1 -107 Hz的频率范围，交流信号振幅的100 mV 测量。单电池是通过添加一个20μm厚的LSM-YSZ复合阴极功能层(CFL)和60μm厚的LSM阴极电流收集层在用丝网印刷的方法获得的溅射的YSZ薄膜得到的。阴极功能层和电流收集层在1150°C，共沉积3 h。共沉积单电池性能用二电极四线装置检查。Ag膏分别涂在阴极和阳极,。Ag网被挤在了Ag膏层是为了更好的电流收集。在700°C，氢气气氛下反应2h，NiO-YSZ 阳极有所减少。减少后,电池的性能用直流电子负载(N3300, Agilent)从温度为700到800°C和湿润H2(2~3% H2O)作为燃料和空气作为氧化剂的条件下进行评估。

3. Results and discussions 结果与讨论

3.1. Effect of anode surface阳极表面效应

Fig. 1a and b shows the SEM images of the NiO–YSZ substrate without AFL layer. It can be seen that the anode substrate

fabricated directly with tape casting method has a porous structure and very coarse surface. Large grains and holes of about 10

μm in lateral sizes are frequently observed. Fig. 1c and d illustrates the 10-μm-thick YSZ film deposited on the coarse anode substrate by reactive magnetron sputtering. It is obvious that large YSZ grains consisting of a dense array of poorly defined fibrous structures dominate the whole film.

图1 a和b显示了扫描电镜的图像NiO-YSZ衬底没有阳极功能层。可以看出用流延成型方法直接制造的阳极衬底具有多孔结构且表面非常粗糙。横向尺寸大约为10μm的大晶粒和孔洞经常被观察到。图1 c和d说明了10微米厚YSZ薄膜沉积的粗大的阳极衬底反应磁控溅射。很明显，巨大的YSZ晶粒包含一组密集阵列的难以定义的纤维结构的占据整个薄膜。

Some of the large grains are separate, and the spaces between neighboring grains may be as large as about 1 μm. After being sintered at 1250 °C for 4 h, the fine fibrous structures inside the grains are sintered together (see Fig. 1d and e). However, the spaces between the grains cannot be mended. This is because no obvious mass diffusion can happen between separated grains. Undoubtedly, such an YSZ film cannot satisfy the gastight criteria for electrolyte films.

一些大晶粒是分开的,相邻颗粒之间的空间可能约1微米那么大。在1250°C 烧结4 h后,细纤维结构内部的颗粒烧结在一起(见图1 d和e)。然而,颗粒之间的空间不能修补。这是因为没有明显的质量扩散会在分离颗粒之间发生。毫无疑问,这样的YSZ电解质薄膜不能满足气密性电解质薄膜的标准。

It is well known that the substrate surface morphology has a very important effect on the films sputtered on it. We had demonstrated that on optically polished glass or quarts substrates, the sputtered YSZ films can be uniform and dense even when the films were as thin as tens of nanometers [8]. On the contrary, the films deposited on a rough surface may reproduce the coarse surface morphology in an exaggerated form. This is because the surface diffusion of adatoms is insufficient to overcome the effects of shadowing resulting from the extrusions or growing grains [9]. Moreover, lower substrate temperature, high deposition pressure, and the oblique components of the deposition flux may also promote the tapered grains with domed tops and voided boundaries [9]. However, these factors are trivial as compared to the shadowing effect for very rough surfaces. Consequently, in order to obtain dense and gastight YSZ electrolyte films for anode supported SOFCs, the anode substrate must be smooth.

众所周知,衬底表面形态对薄膜溅射有着非常重要的影响。我们已经证明,在光学抛光玻璃或若干夸脱衬底上（沉积）,溅射YSZ薄膜即使薄膜只有数十纳米薄，也可以很均匀且密集[8]。相反,薄膜沉积在粗糙表面上可能以一种夸张的形式重现的粗糙表面形态。这是因为表面吸附原子的扩散是不足以克服挤压制品或长大晶粒所导致的附加影响[9]。此外,低衬底温度、高沉积压力和沉积通量的斜组件也可以促进与半球顶部和空心边界的锥形晶粒[9]。然而,这些因素和相比于非常粗糙表面的附加效果是微不足道的。因此,为了获得致密、气密性好的作为阳极支撑固体氧化物燃料电池的YSZ电解质薄膜，阳极衬底必须光滑。

Fig. 2a and b illustrates the cross-sectional and surface morphology of a NiO–YSZ anode substrate modified with an AFL of about 10 μm in thickness. As can be seen, the AFL is much denser and smoother than the original anode substrate (Fig. 1a and b). Our AFM analysis indicates that the RMS surface roughness of the AFL surface was about 200 nm.

图2 a和b说明了NiO-YSZ阳极衬底有阳极功能层改性的横截面和表面形态大约10μm厚度。可以看到,阳极功能层比原来的阳极衬底更致密和更光滑(图1 a和b)。我们的原子力显微分析表明阳极功能层表面的表面粗糙度大约200纳米。

Fig. 2c and d shows the cross-sectional and surface morphology of an as-deposited 10-μm-thick YSZ film. It can be seen that well defined (as compared to Fig. 1c) fine fibrous structures are closely packed; no obvious voids or holes can be observed in the film. By a close examination of Fig. 2d, it can be seen that the YSZ grains (～1μm in lateral sizes) are composed with some even fine structures, which correspond to the fine fibrous structures in the cross-sectional view.

图2c和d显示了沉积态10微米厚YSZ薄膜的横截面和表面形态。可以看出,轮廓分明的(比图1 c)细纤维结构致密,在薄膜上没有明显的空洞或孔洞可观测到。由图2d的仔细检查,可以看出YSZ的晶粒(~1μm横向尺寸)是由一些非常细的结构组成,它对应于剖视图中的细纤维结构。

As will be discussed later, XRD analysis indicate that the size of single crystalline YSZ grains in the as-deposited films was

about 14 nm, which is much smaller than the size of the fibrous structures (a few hundred nanometers in lateral sizes). So the

as-deposited YSZ films have multilevel microstructure features. These features will behave differently in the succeeding sintering processes.

稍后将讨论,XRD分析表明,单个晶体的大小YSZ晶粒沉积态薄膜约14纳米,这是远小于纤维结构的大小(几百纳米横向尺寸)。所以沉积态YSZ薄膜拥有多级微观结构特性。这些特性将表现随着不同烧结过程。

It is widely accepted that a uniform and dense AFL layer composed of fine NiO and YSZ particles is preferable in increasing the three phase boundaries and reducing the anode polarization resistance [10]. In the case of depositing YSZ films by magnetron sputtering, an even more important function of the AFL is to make the anode substrate smoother, because dense and uniform YSZ films can only be prepared on smooth substrates.

人们普遍认为一个均匀的和密集的阳极功能层由更好地增加三相边界和减少阳极极化阻力的细NiO和YSZ 粒子组成[10]。用磁控溅射沉积YSZ薄膜,阳极功能层的一个更重要的功能是使阳极衬底平滑,因为密集的和均匀的YSZ薄膜只能在光滑的衬底制备出来。

Fig. 1.The (a) cross-sectional and (b) surface SEMimages of a coarse anode substrate withoutAFLmodification; the (c) cross-sectional and (d) surface SEMimages of the as-deposited YSZ film; the (d) cross-sectional and (e) surface SEM images of the YSZ film after sintered at 1250 °C for 4 h.

图1所示为没有阳极功能层改性的粗阳极基板的SEM图像，(a)横断面和(b)表面;沉积态YSZ薄膜的SEM图像

(c)横断面和(d)表面;YSZ薄膜在1250℃烧结后的SEM图像4 h (d)横断面和(e)表面。

3.2. Effect of sintering temperature烧结温度的影响

Fig. 3 shows the XRD patterns of the as-deposited and sintered YSZ films. It can be seen that (111) and (220) are the preferred crystalline orientation for all the films. The broad peak feature of the as-deposited film indicates the grains are small. The grain size of the as-deposited films is about 14 nm, which was estimated from the diffraction peaks with the Scherer equation. After sintered at 1150 to 1350 °C, the positions of the YSZ peaks shift to higher diffraction angles. This should be because the

as-deposited film was oxygen deficient. By sintering, the films were fully oxidized, so the lattice parameters became smaller. It is

also noticeable that the YSZ diffraction peaks of the sintered samples are narrow and sharp, which indicate that the crystalline

grains grew larger. The estimated crystalline grain sizes of the sintered samples are around 40 nm. The sizes of the crystalline grain remain almost the same as the sintering temperature increased from 1150 to 1350 °C. This phenomenon

indicates that the main crystallization processes happened before the 1150 °C sintering temperature.

图3显示了沉积态和烧结态YSZ薄膜的XRD图谱。可以看出,(111)和(220)是薄膜的择优晶体取向。沉积态薄膜宽泛的峰值特征表明晶粒很小。沉积态薄膜的晶粒尺寸约为14 nm,从这些衍射峰可以利用谢勒方程估算出。在1150到1350°C之后,烧结后YSZ峰的位置转移到更高的衍射角。这应该是由于沉积态薄膜的氧气不足导致的。通过烧结,薄膜被完全氧化,所以晶格参数变得更小。YSZ烧结样品的衍射峰也明显的变窄且变尖锐,这表明,结晶颗粒长得更大。烧结样品的晶粒尺寸估计约为40纳米。晶粒的尺寸几乎仍和从1150增加到1350°C烧结温度一样。这一现象表明,主要的结晶过程发生在1150°C烧结温度之前。

Fig. 4 shows the SEM images of the YSZ films deposited on the NiO–YSZ anode with smooth AFL layer and sintered at 1150, 1250, 1350 °C for 4 h, respectively. After sintered at 1150 °C, the fibrous structures become blurred (Fig. 4a), but the grains seen from the surface of the YSZ film are still small and rubbly. The surface morphology of the 1150 °C sintered YSZ sample is very similar to that of the as-deposited sample (see Fig. 2d). This indicates that only the crystalline grains inside the fine fibrous structures were sintered well. At this sintering stage, the mass diffusion inside the YSZ films is only limited to a short range.

图4显示了YSZ薄膜沉积拥有光滑阳极功能层的NiO-YSZ阳极上并分别在1150°C,1250°C, 1350°C烧结4 h的SEM图像。在1150°C烧结后,纤维结构变得模糊(图4),但晶粒从YSZ薄膜的表面看上去仍很小,呈碎石状的。1150°C烧结的YSZ样品表面形态非常相似于其沉积态样品（的表面形态）(请参见图2 d)。这表明只有晶粒内部的细纤维结构被很好地烧结。在这个烧结阶段,YSZ薄膜内部的短程质量扩散十分有限。

As the sintering temperature increased to 1250 °C (Fig. 4c and d), the fine fibrous structures merged together, meanwhile, there are some small closed pores formed. It can be seen from Fig. 4d that the grains sintered at 1250 °C grow obviously larger as compared to the1150 °C sintered samples (Fig. 4b). The melting feature of the surface grains and the merged column structures indicate that mass diffusion of longer distances becomes dominate.

随着烧结温度的增加到1250°C(图4 c和d),细纤维结构合并在一起,与此同时,有一些小型封闭孔洞形成。可以从图4d看到晶粒在1250°C烧结与1150°C烧结样品相比有着明显增大(图4 b)。表面晶粒的熔化特性和合并柱状晶结构表明,长程质量扩散成为主导。

Further increasing the sintering temperature to 1350 °C, thefibrous structures became totally indistinguishable; meanwhile, closed pores are increased in quantity and became obviously larger (Fig. 4e). The surface SEM image (Fig. 4f) reveals that the grains grow even larger as compared to the samples sintered at lower temperatures. These features indicate that the YSZ film was over sintered.

进一步提高烧结温度至1350°C,纤维结构变得完全无法区分;与此同时,封闭的孔洞在数量上增加,并明显增大(图4 e)。表面SEM图像(图4)显示,晶粒生长比在较低温度下烧结的样品长更大。这些特征表明,YSZ膜已经烧结过度了。

As compared to the YSZ films prepared by traditional ceramic powder processes, the sputtered YSZ films can be densified at relatively lower sintering temperatures. Based on the above discussions, it is suggested that the optimized sintering temperature for the sputtered YSZ films should be around 1250 °C. While the general densification temperature for the traditional ceramic powder processes is around 1400 °C [11]. A lower sintering temperature is favorable for reducing the cost of SOFCs, and preventing the side chemical reactions which may happen between different cell components [12].

用传统的陶瓷粉末制备过程与YSZ薄膜的制备进行比较,溅射YSZ薄膜可以在烧结温度相对较低的条件下更加致密。基于上述讨论,我们建议对溅射YSZ薄膜应该在1250°C左右烧结温度的进行烧结温度的优化。而一般传统的陶瓷粉末的致密化过程温度约为1400°C[11]。较低的烧结温度有利于减少固体氧化物燃料电池的成本,以及避免可能发生在不同的电池组元之间的副化学反应[12]。

Fig. 2.The (a) cross-sectional and (b) surface SEM images of a smooth anode substrate modified with AFL; the (c) cross-sectional and (d) surface SEM images of the as-deposited YSZ film.

图2所示有阳极功能层改性的光滑阳极衬底的(a)横断面和(b)表面的SEM图像;(c)横断面和(d)沉积态YSZ薄膜表面的SEM图像。

Fig. 3. XRD patterns of as as-deposited YSZ film, and the films sintered at 1150, 1250,and 1350 °C, respectively.

图3所示作为沉积态YSZ薄膜的XRD图谱,和分别在1150°C、1250°C和1350°C烧结的薄膜。

3.3. Ionic conductivity of the YSZ films YSZ 薄膜离子电导率

The ionic conductivity of the 10-μm-thick YSZ film deposited on the AFL modified anode substrate and sintered at 1250 °C for 4 h was characterized by electrochemical impedance spectroscopy (EIS). The results are illustrated in Fig. 5. The activation energy of the YSZ film derived from the Arrhenius plot of log (σT) versus 1/T is 97 kJ/mol, which is close to the reported va lues

of 98–100 kJ/mol[13]. The inset is a typical EIS spectrum, which was taken at 250 °C. Only a single arc was observed in the spectrum. This arc can be attributed to the relaxation of oxygen vacancies inside the lattice of the crystalline YSZ grains. The contribution from the grain boundaries are trivial and cannot be observed. Similar phenomena were also reported by Srivastava [5]. The results show that the area specific resistance (ASR) of the 10-μm-thick YSZ film is 0.08 Ω·cm2 at 750 °C, which is well below the ASR criterion (0.15 Ω cm2) for SOFC applications [3].

沉积在阳极功能改性层阳极衬底的10微米厚的YSZ薄膜的离子电导率和其在1250℃烧结4h电化学阻抗谱(EIS)的特点。结果见图5。YSZ薄膜的活化能来自阿伦尼乌斯的log(σT)与1 / T是97kJ/mol,它与报道值

98~100kJ/mol相接近[13]。插图是一个典型的EIS谱,它是在250°C获得的。在图谱中我们仅仅观察到一个电弧。这个弧可以归因于晶体YSZ晶粒点阵内的氧气空位的弛豫。晶界的贡献微不足道,且不能被观察到的。类似的现象也从Srivastava[5]（的研究中）报道了。结果表明,该10微米厚的YSZ薄膜在750°C下，面电阻(ASR)是0.08Ω·cm2,这远低于固体氧化物燃料电池应用的ASR标准(0.15Ωcm2)[3]。

Fig. 4. The cross-sectional and surface SEM images of a YSZ film deposited on smooth anode substrate and sintered for 4 h at (a) and (b): 1150 °C; (c) and (d):

1250 °C; and (e) and (f): 1350 °C, respectively.

图4所示沉积在光滑的阳极衬底上的YSZ薄膜和烧结4h分别为(a)和(b):1150°C;(c)和(d):1250°C;和(e)和

(f):1350°C横截面和表面SEM图像。

3.4. Single cell performance单电池的性能

In order to examine the feasibility of the sputtering deposited YSZ films for practical SOFC applications, a 10-μm-thick YSZ film deposited on the AFL modified anode substrate and sintered at 1250 °C for 4 h was further processed to a single cell with a 20×20 mm2 active cathode area.

为了检验用于固体氧化物燃料电池的实际应用的溅射沉积YSZ薄膜的可行性,一个10微米厚，在AFL阳极衬底上沉积并在1250°C下烧结4 h的YSZ薄膜，进一步加工成拥有20×20平方毫米活性阴极区的单电池

Fig. 6a shows the single cell performances at 700, 750 and 800 °C, respectively. The open circuit voltages are higher than 1 V and approach to the theoretical values at all the temperatures. This indicates that the YSZ films are dense and gastight. The output power density reaches 0.7 W/cm2 at 750 °C by using humidified H2 and air. The cell performances were stable during the test and reproducible between different batches of cells.

图6a 显示了分别在700°C,750和800°C单电池性能。开路电压高于1 V并且接近于理论值的温度。这表明YSZ 薄膜致密且气密性好。在750°C湿润H2和空气环境下使用，输出功率密度达到0.7 W/cm2。电池性能在测试期间是稳定的并且在不同批次的电池之间可再生产。

Fig. 6b shows the cross-sectional microstructure of the single cells after tested. The porosity of the anode substrate increased obviously as compared to Fig. 2a. The AFL also became porous after the NiO component was reduced to Ni. The YSZ film was dense and uniform, neither cracks nor delaminationscould be found throughout the cell.

图6b显示了测试后的单电池横截面积的微观组织结构。阳极衬底的孔隙度相比于图2a有着明显增加。在NiO 组元减少为Ni之后，阳极功能层也变得多孔。YSZ膜致密且均匀,在整个电池中不能找到裂纹和脱层。

4. Conclusions结论

YSZ films for anode-supported SOFCs were prepared by reactive sputtering method. It was found that the surface morphology of anode substrate has a very importanteffect on the quality of the sputtered films. By applying an anode functional layer and making the anode surface smooth, dense and uniform YSZ films of 10 μm in thickness were successfully fabricated. It is suggested the optimized densification condition for the deposited YSZ films is sintering at 1250 °C for 4 h. Single cells with sputtered YSZ film as electrolyte and LSM–YSZ as active cathode materials were tested. 1.08 V open circuit voltage and a 700 mW/cm2 maximum power density were achieved at 750 °C by using humidified H2 as fuel and air as oxidant.

用于阳极支撑固体氧化物燃料电池YSZ薄膜是由反应溅射的方法。阳极衬底的表面形态受到溅射膜的质量非常重要的影响。通过应用一个阳极功能层和拥有光滑、致密、均匀的且10μm厚的阳极表面的YSZ薄膜成功制造。我们建议沉积的YSZ薄膜在致密化条件烧结，条件优化为1250°C、4 h。用溅射YSZ膜的单电池作为电解质和LSM-YSZ作为活性阴极材料进行了测试。在750°C，湿氢气作为燃料和空气作为氧化剂的条件下使用，它可以实现1.08 V开路电压和700 mW / cm2的最大功率密度。

Acknowledgement致谢

This work was partially supported by National Natural Science Foundation of China (Grant No. 52772109).

这项工作资金部分是由中国国家自然科学基金支持的(批准号52772109)。

Fig. 5.Arrenhius plot of the YSZ film deposited on smooth anode substrate and sintered at 1250 °C for 4 h; The inset: a typical EIS spectrum taken at 250 °C. 图5所示沉积在光滑阳极衬底的YSZ薄膜在1250°C烧结4 h的阿伦尼乌斯图;

插图:在250°C下，一个典型的EIS光谱。

Fig. 6. (a) Voltage–current density, and power density–current density curves of a single cell with 10-μm-thick YSZ film deposited on an AFL modified anode substrate and sintered at 1250 °C for 4 h; (b) The cross-sectional SEM image of the single cell after tested. The active cathode material is LSM–YSZ, and the active cathode area is 20×20 mm2.

图6所示。(a)沉积在一个阳极功能改性阳极衬底上的10微米厚和在1250°C烧结4 h的YSZ薄膜单电池的电压-电流密度和功率密度-电流密度曲线;(b)测试后单电池的横截面的扫描电镜图像。LSM-YSZ是活性阴极材料,活性阴极面积20×20平方毫米。

References参考文献

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[4] J.A. Thornton, A. Penfold, in: J.L. Vossen, W. Kern (Eds.), Thin Film Processes,Academic, New York, 1978, p. 76.

[5] P.K. Srivastava, T. Quach, Y.Y. Duan, R. Donelson, S.P. Jiang, F.T. Ciacchi, S.P.S.Badwal, Solid State Ionics 99 (1997) 311.

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expand/enlarge one’s scope of knowledge knowledge reserve/base/storage theoretical knowledge practical skills social experience broaden one’s knowledge base promote one’s overall/ comprehensive competence accumulate experiences learn lessons from past experiences Work and experience the scarcity of employment o p p o r t u n i t i lay the foundations for career p r o s p e r i t y

学生造句--Unit 1

●I wonder if it’s because I have been at school for so long that I’ve grown so crazy about going home. ●It is because she wasn’t well that she fell far behind her classmates this semester. ●I can well remember that there was a time when I took it for granted that friends should do everything for me. ●In order to make a difference to society, they spent almost all of their spare time in raising money for the charity. ●It’s no pleasure eating at school any longer because the food is not so tasty as that at home. ●He happened to be hit by a new idea when he was walking along the riverbank. ●I wonder if I can cope with stressful situations in life independently. ●It is because I take things for granted that I make so many mistakes. ●The treasure is so rare that a growing number of people are looking for it. ●He picks on the weak mn in order that we may pay attention to him. ●It’s no pleasure being disturbed whena I settle down to my work. ●I can well remember that when I was a child, I always made mistakes on purpose for fun. ●It’s no pleasure accompany her hanging out on the street on such a rainy day. ●I can well remember that there was a time when I threw my whole self into study in order to live up to my parents’ expectation and enter my dream university. ●I can well remember that she stuck with me all the time and helped me regain my confidence during my tough time five years ago. ●It is because he makes it a priority to study that he always gets good grades. ●I wonder if we should abandon this idea because there is no point in doing so. ●I wonder if it was because I ate ice-cream that I had an upset student this morning. ●It is because she refused to die that she became incredibly successful. ●She is so considerate that many of us turn to her for comfort. ●I can well remember that once I underestimated the power of words and hurt my friend. ●He works extremely hard in order to live up to his expectations. ●I happened to see a butterfly settle on the beautiful flower. ●It’s no pleasure making fun of others. ●It was the first time in the new semester that I had burned the midnight oil to study. ●It’s no pleasure taking everything into account when you long to have the relaxing life. ●I wonder if it was because he abandoned himself to despair that he was killed in a car accident when he was driving. ●Jack is always picking on younger children in order to show off his power. ●It is because he always burns the midnight oil that he oversleeps sometimes. ●I happened to find some pictures to do with my grandfather when I was going through the drawer. ●It was because I didn’t dare look at the failure face to face that I failed again. ●I tell my friend that failure is not scary in order that she can rebound from failure. ●I throw my whole self to study in order to pass the final exam. ●It was the first time that I had made a speech in public and enjoyed the thunder of applause. ●Alice happened to be on the street when a UFO landed right in front of her. ●It was the first time that I had kept myself open and talked sincerely with my parents. ●It was a beautiful sunny day. The weather was so comfortable that I settled myself into the

雅思口语素材

U s e f u l E x p r e s s i o n s: Words and phrases Friends and communication: mutual understanding solidify/ strengthen/ enhance/ promote communication / connection with relationship network/circle of friends cultivate/develop friendship with sb. keep steady relationship with sb. establish interpersonal networksac build up the social circle spur message transmission Knowledge and experience widen one’s outlook broaden one’s vision/horizon acquire knowledge and skills comprehensive/overall quality expand/enlarge one’s scope of knowledge knowledge reserve/base/storage theoretical knowledge practical skills social experience broaden one’s knowledge base promote one’s overall/ comprehensive accumulate experiences competence learn lessons from past experiences Work and experience the scarcity of employment opportunities lay the foundations for career prosperity immerse oneself in endless job tasks boost/augment/enhance efficiency be adept in boost one’s c ompetitiveness Health and pressure diminish individuals' leisure time drive away lassitude lighten one’s burden homework/workforce overload

英语句子结构和造句

高中英语~词性~句子成分~语法构成 第一章节：英语句子中的词性 1.名词：n. 名词是指事物的名称，在句子中主要作主语.宾语.表语.同位语。 2.形容词;adj. 形容词是指对名词进行修饰~限定~描述~的成份，主要作定语.表语.。形容词在汉语中是（的）.其标志是: ous. Al .ful .ive。. 3.动词：vt. 动词是指主语发出的一个动作，一般用来作谓语。 4.副词：adv. 副词是指表示动作发生的地点. 时间. 条件. 方式. 原因. 目的. 结果.伴随让步. 一般用来修饰动词. 形容词。副词在汉语中是（地）.其标志是：ly。 5.代词：pron. 代词是指用来代替名词的词，名词所能担任的作用，代词也同样.代词主要用来作主语. 宾语. 表语. 同位语。 6.介词：prep.介词是指表示动词和名次关系的词，例如：in on at of about with for to。其特征：

介词后的动词要用—ing形式。介词加代词时，代词要用宾格。例如：give up her（him）这种形式是正确的，而give up she（he）这种形式是错误的。 7.冠词：冠词是指修饰名词，表名词泛指或特指。冠词有a an the 。 8.叹词：叹词表示一种语气。例如：OH. Ya 等 9.连词：连词是指连接两个并列的成分，这两个并列的成分可以是两个词也可以是两个句子。例如：and but or so 。 10.数词：数词是指表示数量关系词，一般分为基数词和序数词 第二章节：英语句子成分 主语：动作的发出者，一般放在动词前或句首。由名词. 代词. 数词. 不定时. 动名词. 或从句充当。 谓语：指主语发出来的动作，只能由动词充当，一般紧跟在主语后面。 宾语：指动作的承受着，一般由代词. 名词. 数词. 不定时. 动名词. 或从句充当. 介词后面的成分也叫介词宾语。 定语：只对名词起限定修饰的成分，一般由形容

近期雅思口语卡片新题素材汇总

近期雅思口语卡片新题素材汇总 人物Describe a classmate of yours Describe a good friend Describe a happy person Describe a colleague Describe a neighbor Describe your own personality Describe a family member Describe a child you know Describe an old person Describe an old person who has influenced you the most Describe a successful person Describe a singer Describe a sportsman Describe a movie star Describe a character in TV or movie Describe a teacher of yours Describe a famous person that you want to spend a day with.地点Describe a building at schools Describe a historical place

Describe a monument Describe an interesting building Describe a lake, river or sea. Describe a peaceful place Describe a leisure place Describe a park Describe a place of interest Describe a natural beauty Describe a city you want to live in Describe a place you have visited Describe a place you always go for shopping

六级单词解析造句记忆MNO

M A: Has the case been closed yet? B: No, the magistrate still needs to decide the outcome. magistrate n.地方行政官，地方法官，治安官 A: I am unable to read the small print in the book. B: It seems you need to magnify it. magnify vt.１．放大，扩大；２．夸大，夸张 A: That was a terrible storm. B: Indeed, but it is too early to determine the magnitude of the damage. magnitude n.１．重要性，重大；２．巨大，广大 A: A young fair maiden like you shouldn’t be single. B: That is because I am a young fair independent maiden. maiden n.少女，年轻姑娘，未婚女子 a.首次的，初次的 A: You look majestic sitting on that high chair. B: Yes, I am pretending to be the king! majestic a.雄伟的，壮丽的，庄严的，高贵的 A: Please cook me dinner now. B: Yes, your majesty, I’m at your service. majesty n.１．［Ｍ－］陛下（对帝王，王后的尊称）；２．雄伟，壮丽，庄严 A: Doctor, I traveled to Africa and I think I caught malaria. B: Did you take any medicine as a precaution? malaria n.疟疾 A: I hate you! B: Why are you so full of malice? malice n.恶意，怨恨 A: I’m afraid that the test results have come back and your lump is malignant. B: That means it’s serious, doesn’t it, doctor? malignant a.１．恶性的，致命的；２．恶意的，恶毒的 A: I’m going shopping in the mall this afternoon, want to join me? B: No, thanks, I have plans already. mall n.（由许多商店组成的）购物中心 A: That child looks very unhealthy. B: Yes, he does not have enough to eat. He is suffering from malnutrition.

Simon考官范文-雅思口语素材2(Cook整理)

一.雅思P2相关话题 一日假期 和外国朋友一起吃饺子的建议 1.The best way to eat a dumpling is in one bite. “Dumplings are designed to be consumed in one mouthful, as it’s the best way to enjoy the combination of the meat filling and the very thin and springy flour wrapper,” If you can’t use chopsticks, eat your dumplings with your fingers. Avoid using a fork at all costs, as piercing the dumpling will compromise the flavour. 3.Mix two parts vinegar with one part soy sauce for the perfect dumpling sauce. Add young ginger slices too， Chili oil is also a great addition when available. 4.Dumplings are just one element of dim sum. “Dim sum doesn’t just include dumplings. It’s also braised dishes like pork ribs, chicken feet, and beef balls. It’s actually small tapas-style dishes that are eaten in Cantonese restaurants at lunchtime,” 5.Xiao long bao dumplings are different from others as they contain broth. They originated in the Jiangnan region of China and are prepared in bamboo steaming baskets called xiao long, hence the name. 6.When eating xiao long bao or a dumpling with a ~soupy~ interior, opt for chopsticks and a spoon. “As soon as the dumplings arrive at your table, lift one from the steamer basket onto a soup spoon. Next, tear the skin of the dumpling by pressing the chopsticks from the side of the dumpling onto the spoon. The broth will ooze out onto the spoon. Sip the soup then enjoy the dumpling in one mouthful.” 7.You can tell whether your dumpling was cooked fresh or frozen by looking at the skin. “The skin of a freshly made dumpling is springy and light. “Frozen ones tend to be soggy.” 8.When makingdumplingsat home, try to keep your packages small.

base on的例句

意见应以事实为根据. 3 来自辞典例句 192. The bombers swooped ( down ) onthe air base. 轰炸机 突袭 空军基地. 来自辞典例句 193. He mounted their engines on a rubber base. 他把他们的发动机装在一个橡胶垫座上. 14 来自辞典例句 194. The column stands on a narrow base. 柱子竖立在狭窄的地基上. 14 来自辞典例句 195. When one stretched it, it looked like grey flakes on the carvas base. 你要是把它摊直, 看上去就象好一些灰色的粉片落在帆布底子上. 18 来自辞典例句 196. Economic growth and human well - being depend on the natural resource base that supports all living systems. 经济增长和人类的福利依赖于支持所有生命系统的自然资源. 12 1 来自辞典例句 197. The base was just a smudge onthe untouched hundred - mile coast of Manila Bay. 那基地只是马尼拉湾一百英里长安然无恙的海岸线上一个硝烟滚滚的污点. 6 来自辞典例句 198. You can't base an operation on the presumption that miracles are going to happen. 你不能把行动计划建筑在可能出现奇迹的假想基础上.

(完整word版)雅思口语素材整理汇总

雅思口语素材训练 by Tina Li Do you like music??A—肯定:Definitely yes, everyone enjoys music, and I am no exception! I love... 否定 :Well, honestly speaking, music is really not my cup of tea, simply because... ( 给出直接原因) What—pop, techno ( 电音音乐), hip-hop, rock, meditation ( 冥想乐) and especially light music.( 罗列名词) Where—Normally speaking, I would like to listen to music with my earphones when I take a ride on public transportation. ( 给出一个具体的场景) When—As long as I couldn’t go to sleep, I’d like to listen to some light music to calm myself down. ( 给出一个条件 :As long as I..., I would...)

Who—My most favourite singers include Adele, James Blunt, Avril Lavigne, and so forth. ( 喜欢的歌手) Why—I am fond of music mainly because it can cheer me up greatly when I feel down/low/ blue/bored/tired/depressed. ( 心情不好的时候让我高兴起来)?Besides, I also believe that music is an indispensable part of culture and tradition, through which I could have a better understanding of different cultures around the world, including cowboy culture, African-American street culture, the three main reli- gions and so on. ( 有助于理解不同的文化) Do you like watching movies?? A—Speaking of movies, yes, I am a big fan of all types of movies, such as...?What—comedy, action, romance, sci-fi, manga, vampire, zombie, animation...