氧化锆固体电解质电子导电性能的测定

本文采用从铝液（７００￣１０００℃）和银液（１０００￣１１００℃）中抽氧的方法，测定了自制氧化锆固体电解质管的电子特征氧分压Ｐｏ２以及Ｅ－Ｉ，Ｅ－ｔ曲线，得出自制电解质管在９３０℃渗碳气氛中使用时，可以忽略电子电导对电池电势的影响的结论。     

用铝液抽氧法测量氧化锆的电子特征氧分压

用从铝液和银液中抽氧的库仑滴定法测定了自制氧化钇稳定的氧化锆固体电解质的电子特征氧化压力Pθ，结果表明，900度时电子特征氧分压的范围是10^-26-10^-28kPa，自制氧化锆电解质可用于渗碳气氛氧浓度的测量而不必考虑电子电导对浓差电势的影响。用铝液能实现低温下电子 特征分压的测量。     

ZO—系列氧化锆氧量分析仪常见故障分析及处理方法

一、前言 ZO-系列氧化锆氧量分析仪是八十年代开始应用的先进的气体氧量分析仪。其工作原理是根据能斯特(Nernst)公式计算的。氧化钇稳定的氧化锆材料是一种高性能的氧离子导体,氧化锆锆管内外侧涂以多孔铂电极,在高温(大于600℃)时,当氧化锆锆管内外两侧分别通以不同氧浓度的气体时,就形成氧浓差电池: (PO_2′)Pt/ZrO_2-Pt(PO_2″) 阴极:O_2 4e=2O~(2-) 阳极:2O~(2-)=O_2 4ePO_2′和PO_2″分别为参比气氧分压和被测气氧分压,氧浓差电池电动热E与氧分压的关系可用能斯特(Nernst)公式表示:     

镱铝共掺杂氧化锆电解质材料制备与性能

采用固相法制备了镱铝共掺杂氧化锆电解质材料。实验结果表明:Al_2O_3(氧化铝)能促进电解质的烧结并提高电解质的抗弯强度。Al_2O_3对电导率的影响与Yb_2O_3(氧化镱)的掺杂量有关,仅当Yb_2O_3掺杂量为6%(摩尔分数)时,Al_2O_3掺杂有利于氧离子电导率。6%(摩尔分数)Yb_2O_3和0.5%(摩尔分数)Al_2O_3共掺杂的氧化锆电解质具有优异的抗弯强度和最高的氧离子电导率,以其作为支撑体的电池在800℃的功率密度为0.40W/cm~2。     

片式ZrO2氧浓差电池的制作及其特性研究

采用共沉淀方法制备YSZ粉料,经低温(1300℃)烧结,得到圆片状YSZ烧结体(Y_2O_3含量8mol%),采用热分解法涂制铂电极,采用新颖的热辐射压封法实现电解质圆片与Al_2O_3管封接,制成了氧浓差电池,测量了固体电解质的密度、电导率以及不同温度、不同氧分压、不同氧流量下浓差电池的电动势,通过电势一氧分压关系曲线和电势-氧流量曲线的实验测量,得到了与固体电解质电质、气体渗透性相关的参数。     

Al2O3掺杂对YSZ固体电解质烧结及电性能的影响

研究了用常规共沉淀法掺杂Al2O3对YSZ固体电解质的烧结及电性能的影响．结果表明：适量的Al2O3能提高YSZ材料的烧结性能，促使其致密化，但过量的Al2O3对材料的致密化不利；同时，材料的晶界电导随Al2O3含量的增大表现出先增大后减小的变化趋势，这与Al2O3对YSZ晶界两方面的不同影响有关，Al2O3偏析于晶界一方面能清除晶界上对氧离子电导不利的SiO2，但另一方面也会降低晶界空间电荷层中的自由氧离子空穴的浓度．     

氧化锆固体电解质的特征氧分压测定

ZrO_2的特征氧分压 P_n 即在它的离子电导率与其电子电导率相等时的氧分压是表征固体电解质的离子迁移数的重要参数。本文讨论了 P_n 的测定原理,并用极化电动势法结合恒流方波脉冲技术测定了 ZrO_2(8.2mol%MgO)的 P_n,在测定的温度范围内 P_n 与绝对温度 T 的倒数表现出较好的线性关系,并能以 lgP_n=17.72-5.921×10~4/T 来表示。根据所测的 P_n,估计了材料在任何氧分压时的离子迁移数并计算了材料表现为优良的快离子导体时所能应用的氧分压范围。本文还对实验结果和数据处理进行了讨论。     

甲烷在Ni/Al2O3催化剂上积碳与失活行为研究

采用浸渍法制备Ni/Al2O3催化剂,研究反应条件对甲烷裂解生成碳产物形貌的影响和催化剂的失活机制.结果表明:在40Ni/Al2O3催化剂上碳生成物的沉积形式均呈纤维状结构,反应温度越高、空速越大,碳纤维的直径越小;碳在金属颗粒体相中的扩散是碳纳米纤维生长过程的速率控制步骤,当碳的生成速率低于碳在Ni中的体相扩散和迁移速率,生成的炭以纤维状结构生长.     

掺入Al_2O_3对固体氧化物电解质材料YSZ性能影响的研究

在立方相的钇稳定化氧化锆 [(ZrO2 ) 0 .92 (Y2 O3) 0 .0 8](YSZ)中 ,掺入少许不同量的Al2 O3,研究其对基体材料YSZ的烧结性能、机械强度和导电性能的影响 ,并对其机理进行了分析。实验结果表明 ,掺入Al2 O3能够明显降低电解质烧结温度 ,改善烧结性能。在 130 0℃烧结 1h后 ,少量掺杂Al2 O3的样品晶粒尺寸明显比纯YSZ样品的小 ;从阻抗谱图上可以看出 ,随着Al2 O3含量的增加 ,晶界电阻不断减小 ,在掺杂比例为 4 % (质量分数 )时 ,达到最小点。而后随着Al2 O3含量的增加 ,晶界电阻又呈上升趋势。用纯YSZ和掺 4 % (质量分数 )Al2 O3的材料制成SOFC ,得到伏安特性曲线 ,结果表明 ,掺 4 % (质量分数 )Al2 O3的性能比YSZ好。     

PVDF-HFP基复合多孔聚合物电解质膜的研制

聚偏氟乙烯-六氟丙烯共聚物(PVDF-HFP)多微孔膜在锂离子电池领域中具有很好的应用前景.采用Bellcore制膜法,用纳米材料对PVDF-HFP为基质的聚合物微孔膜材料进行了改性.利用XRD,SEM,交流阻抗等测试手段对电解质膜的晶体结构、微观形貌、电化学性能等进行了表征.结果表明:改性后聚合物电解质膜的孔隙率增加、结晶度降低,PVDF-HFP/SiO2和PVDF-HFP/Al2O3聚合物电解质隔膜的电导率(20℃)分别达到2.762×10-3S/cm和3.517×10-3S/cm,相应的离子迁移数分别为0.80和0.82.     

The effect of deposition parameters on the properties of yttria-stabilized zirconia thin films

Yttria-stabilized zirconia (YSZ) films were deposited by RF magnetron sputtering in order to examine the effects of sputtering conditions on the properties of the resulting thin-films. X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS) and scanning electron microscopy (SEM) were used to characterize the films. Additionally, films were deposited on alumina bars to examine the effect of the coatings on the strength of a brittle substrate. RBS analysis indicated that the ratio of oxygen to zirconium in the films varied from 1.84 to 2.10. XRD showed that there was a wide variation in the amount of monoclinic and tetragonal phases that appeared to be related to the O:Zr ratio. Despite these variations, there was no significant difference found in flexural strength found among the groups of alumina bars that were coated with YSZ. The likely cause is the columnar grain morphology of the deposited thin-films, which does not allow strengthening mechanisms to become operative.     

片式氧传感器电解质薄膜的制备及其性能研究

确定了钇掺杂稳定氧化锆超细粉料和有机添加剂组成的浆料的配比,流延并烧结成了用于片式氧传感器的陶瓷薄膜。通过浆料粘度变化分析了分散剂的作用效果,研究了粘结剂和增塑剂对成膜效果和素坯相对密度的影响;采用综合热分析仪等手段研究了浆料中有机添加剂的烧除温度和热失重变化,并设计了合适的烧结制度;利用X射线衍射(XRD)及电子扫描显微镜(SEM)分析了最终烧结体的晶体结构和微观形貌;测量了抗热震及电性能。研究结果表明:素坯薄膜相对密度达55%,素坯内颗粒分散均匀,无硬团聚;采用相应的烧结制度在最佳烧结温度1450℃下得到了相对于理论密度达98%,晶粒均匀,晶界明显,几乎没有气孔的致密化薄膜;其抗热震性能达45次以上,电性能良好,是用于片式氧传感器的理想薄膜材料。     

Al_2O_3掺杂8YSZ固体电解质的烧结及性能研究

通过化学共沉淀法制备Al2O3掺杂的8YSZ固体电解质,并对其进行烧结和性能检测。试验结果表明,掺杂Al2O3有利于降低烧结温度,促使烧结体致密化。并且随着Al2O3掺杂量的增大,晶粒的电导逐渐降低。当Al2O3的加入量少于1.5%(w)时,并没有起到晶界电导改善的作用,反而使晶界性能恶化。     

YSZ thin films deposited by e-beam technique

YSZ thin films were grown evaporating cubic and tetragonal phase ZrO₂ stabilized by 8 wt.% of Y₂O₃ (8% of YSZ) ceramic powders by using e-beam deposition technique. Operating technical parameters that influence thin film properties were studied. The influence of substrate crystalline structure on growth of deposited YSZ thin film was analyzed there. The YSZ thin films (1.5-2 μm of thickness) were deposited on three different types of substrates: Al₂O₃, optical quartz (SiO₂), and Alloy 600 (Fe-Ni-Cr). The dependence of substrate temperature, electron gun power, and phase of ceramic powder on thin film structure and surface morphology was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The substrate temperature was changed in the range of 20-600° C (during the YSZ thin film deposition) and its influence on the crystallinity of deposited YSZ thin films was analyzed. It was found that electron gun power and substrate temperature has the influence on the crystallite size, and texture of YSZ thin films. Also, the substrate has no influence on the crystal orientation. The crystallite size varied between 20 and 40 nm and increased linearly changing the substrate temperature. The crystal phase of evaporated YSZ powder has the influence on the structure of the deposited YSZ thin films.     

Influences of deposition rate and oxygen partial pressure on residual stress and microstructure of YSZ thin films

Yttria-Stabilized Zirconia (YSZ) thin films were deposited on borosilicate crown glass substrates using electron beam evaporation technique and controlling technological parameters: deposition rate and oxygen partial pressure. Spectrophotometry, optical interferometry and X-ray diffraction were used to investigate how the thin film optical properties, residual stresses, and structure depend on these parameters. The results showed that the deposition rate had a significant influence on the increase of the refractive index of YSZ thin films while the oxygen partial pressure had less influence on it. In all samples, the tensile stress increased with the increasing of deposition rate and the decreasing of oxygen partial pressure. Meanwhile, all deposited films were poly-crystallizations, while crystallite size and preferential orientation of YSZ thin films changed as a function of deposition rate and oxygen partial pressure. The variations of the optical spectra and residual stress corresponded to the evolution of the film structures induced by the deposition parameters.     

氧化铝纳米线的催化氧化法制备及表征

以汞为介质, 通过铝的催化氧化反应制备出氧化铝纳米线. 采用FE-SEM、TEM、EDX、XRD、IR等手段对氧化铝纳米线进行表征. 结果表明, 氧化铝纳米线直径为5~15nm, 无定型结构. 随着反应温度、铝纯度、反应气氛中的氧含量升高, 氧化铝纳米线比表面积增大; HgCl₂溶液浓度、铝浸入溶液的时间对氧化铝纳米线的比表面积没有明显影响.     

Sol–gel synthesis and characterization of mesoporous yttria-stabilized zirconia membranes with graded pore structure

Mesoporous yttria-stabilized zirconia (YSZ) membranes can be used for liquid phase applications in harsh environments and as supports for ultra-thin dense ceramic, carbonate, or metallic membranes. This article reports on the synthesis and characterization of three-layer mesoporous ceramic membranes consisting of a mesoporous YSZ layer, a macroporous YSZ intermediate layer, and macroporous α-alumina support. The macroporous YSZ intermediate layer was coated on the alumina support using a suspension of submicron-sized YSZ powders, and the mesoporous YSZ layer was obtained by dip-coating with diluted zirconia sol doped with yttrium nitrate. The mesoporous YSZ layer has desired cubic phase structure. Crack-free mesoporous YSZ membranes could be obtained by multiple dip-coating, drying, and calcination using a dilute YSZ sol at a concentration of 0.014 M with the help of using a drying control chemical additive. The 5 times dip-coated mesoporous YSZ membranes were about 1 μm in thickness with an average pore diameter of 3 nm. The mesoporous YSZ membranes exhibited Knudsen separation factor. The characteristics of the dip-coating process for the mesoporous YSZ membranes on the macroporous YSZ support are similar to those on the macroporous alumina support.     

Growth and structure of epitaxial CeO2 films on yttria-stabilized ZrO2

Thirty to a hundred-nm thick epitaxial CeO₂ layers are grown on YSZ (100), (110) and (111) surfaces of yttria-stabilized ZrO₂ (YSZ) by electron beam evaporation of Ce in oxygen at reduced pressure. Their growth, structure and thermal stability are studied with several bulk and surface sensitive techniques including Rutherford backscattering spectrometry, cross-sectional high resolution electron microscopy, low energy electron diffraction and low energy reflection electron microscopy. Excellent epitaxy is obtained on all YSZ surfaces at a growth temperature of 750 K. The surfaces of films grown on (111)-oriented substrates are flat, whereas those on the other substrates are faceted into small (111) planes. The grain sizes in the films are in the 10 nm range and smaller.     

Electron emission measurements and the defect structure of α-Al2O3

In this article, electron emission is used to study the defect structure of alumina. The need of a direct measurement of the position of the Fermi level (or the electron concentration in the conduction band) is shown by discussing the actual electrical data on alumina. The emission has been measured over a large temperature range (1400 to 2400 K) and the emission of a technical polycrystalline alumina is reported up to the melting temperature under a controlled oxygen partial pressure. Additional results are reported for titanium- and iron-doped polycrystalline aluminas. The results are discussed from two points of view. First the quantitative data concerning the work function are taken into account and the contribution of the surface layer is discussed. Secondly, the dependency of the electron emission on the oxygen partial pressure is explained by the defect chemistry of the oxide. The absence of variation of the electron concentration in a certain range of is due to a self compensation between donor and acceptor impurities.