低成本电化学法制备RE2Zr2O7缓冲层

为了降低第二代高温超导涂层导体的制备成本,采用电化学法(ED),在双轴织构的Ni-5at%W(Ni-5W)金属基带上分别成功制备出了具有较好c轴取向的La2Zr2O7(LZO)和Gd2Zr2O7(GZO)缓冲层.通过与磁控溅射方法(MS)相结合,制备出MS-CeO2/ED-RE2Zr2O7双层结构,用以取代完全用磁控溅射方法(MS)制备的多层缓冲层结构.电化学法得到的60 nm LZO缓冲层的面内和面外织构半高宽分别为7.2°和6.8°,同样厚度的GZO缓冲层的面内和面外半高宽分别为6.7°和5.8°.之后用脉冲激光沉积(PLD)在ED-LZO/Ni-5W,ED-GZO/Ni-5W,MS-CeO2/ED-LZO/Ni-5W三种结构的缓冲层上分别制备出具有超导性能的YBa2Cu3O7-δ(YBCO)超导层.     

YBCO覆膜导体低成本制备研究

报道新近发展的离子束结构改性(ISM)技术以及同步织构(STEX)技术在YBCO覆膜导体制备中的最新进展。采用TFA-MOD工艺成功的在LaAlO_3(100)衬底上制备出了临界电流密度高达6.5 MA/cm~2 (77K,0T)的YBCO超导薄膜,其超导转变温度接近91K;同时还在LaAlO_3(100)衬底上成功地采用溶胶-凝胶工艺制备出了具有高度外延双轴织构取向的SrTiO_3缓冲层材料;在YSZ(100)衬底上采用溶胶-凝胶工艺制备出了具有高度双轴织构取向的CeO_2缓冲层材料。随后在这两种衬底上采用TFA-MOD工艺沉积的YBCO超导薄膜也获得了超过1MA/cm~2(77K,0T)的临界电流密度。作为制备实用化YBCO超导带材的新路线,在数厘米长的IBAD-YSZ/Hastelloy金属基带模板上,采用低成本化学溶液方法依次制备出了高质量的CeO_2缓冲层和YBCO超导薄膜,获得了高达1.2MA/cm~2(77K,0T)的临界电流密度。为长超导带材的制备打下了很好的基础。提出了在金属基带上制备YBCO覆膜导体的新方法一同步织构(STEX)法。用该方法可以有效解决RABiTS方法中的金属基带热处理变软...     

窄流道式MOCVD制备YGBCO超导层研究

金属有机化学气相沉积能连续、快速的沉积高温超导带材YBa_2Cu_3O_(7-x)(YBCO)超导层。但金属有机源的利用率与薄膜沉积速率以及沉积一致性难以兼顾,制备YBCO高温超导带材的成本居高不下。本文提出了一种新的窄流道式反应室以改进薄膜沉积的一致性。在200 mm长度腔体中沉积的280 nm厚的Y_(0.5)Gd_(0.5)Ba_2Cu_3O_(7-x)薄膜J_c分布在3.2～3.5 MA/cm~2(77 K,0 T),面外、面内半高宽值分别在1.39°～1.49°和1.88°～2.13°,表面平整致密。YBCO薄膜良好的一致性表明该窄流道反应室对制备YBa_2Cu_3O_(7-x)超导带材有好的实用性。     

YBa2Cu3O7-δ薄膜的BaCl2/BaF2-MOD法制备及超导特性研究

传统三氟乙酸金属有机化学溶液沉积法(TFA-MOD)制备YBa₂Cu₃O_7-δ (YBCO)超导层,Ba倾向于与F结合,从而避免BaCO₃的形成。本工作开展了新型基于BaCl₂/BaF₂途径的化学溶液法生长YBCO超导薄膜的研究。重点研究了添加Cl对YBCO薄膜晶粒取向、微观结构和超导性能的影响,并通过生长反应的热化学计算,分析了BaCl₂途径YBCO薄膜的物相转变机制。结果表明:添加Cl有利于抑制a轴晶粒取向,促进c轴晶粒成核。添加Cl的YBCO双层膜起始转变温度(Tc-onset)没有明显变化,约为89.6 K,其临界电流密度(Jc)显著提升, Jc达到2.07 MA/cm²(77K,自场)。此外,生长反应过程的物相转变分析表明Cl优先与Ba结合形成BaCl₂,有效避免BaCO₃的形成。本研究结果表明:添加Cl对制备YBCO超导厚膜有促进作用,这为MOD法制备YBC...     

MOD法在种子层/Ni-W上制备La0.4Sr0.6TiO3薄膜的研究

采用金属有机沉积法(MOD)在双轴织构的Ni-5%(原子分数)W基带上制备了SrTiO3种子层,然后再在种子层上沉积La0.4Sr0.6TiO3薄膜.SEM图像显示种子层颗粒分布均匀,大小基本一致.通过XRD和SEM研究了不同热处理温度对La0.4Sr0.6TiO3薄膜取向和微观形貌的影响,结果显示,在Ar-4%H2气...     

无氟化学溶液法制备YBa_2Cu_3O_z超导薄膜

采用自主开发的无氟化学溶液沉积法在(00l)LaAlO_3单晶片上制备了YBa_2Cu_3O_z(YBCO)超导薄膜。研究了高温热处理过程中不同成相气氛和渗氧温度对YBCO薄膜结构和性能的影响。采用X射线衍射仪对薄膜进行了织构分析,通过扫描电镜和原子力显微镜观察了薄膜的表面形貌。采用磁性能测试系统测量了薄膜的超导转变温度和磁化曲线。实验结果表明,在干燥的热处理气氛和400℃渗氧制备的YBCO薄膜具有更加优异的性能。     

低氟MOD法制备Zr掺杂YBCO薄膜的研究

在金属有机盐沉积（MOD）法制备YBCO薄膜的工艺中, 采用无F的α甲基丙烯酸铜取代原来的三氟乙酸铜, 可以降低前驱溶液中大约50%的氟含量. 研究表明, 该方法大大缩短了YBCO前驱薄膜受热分解的时间, 仅为原来的1/7. 通过XRD、SEM分析发现, 该方法可以制备成分单一、具有良好立方织构的YBCO薄膜, 且薄膜表面平整致密, 没有裂纹, 临界温度(T_c)达到了90K左右, 77K、自场下的临街电流密度(J_c)达到了2.84MA/cm². 通过在制备的YBCO薄膜中引入6mol% 的 Zr元素掺杂, 有效地提高了YBCO薄膜在外加磁场下的超导性能.     

高性能Y_(0.5)Gd_(0.5)BCO薄膜的研究

通过在YBCO前驱溶液中加入醋酸钆(Gd(CH_3COO)_3),使元素Gd部分取代Y,成功地制备了Y_(0.5)Gd_(0.5)BCO薄膜,该薄膜成分单一且具有很好的c轴取向.通过对Y_(0.5)Gd_(0.5)BCO薄膜和YBCO、GdBCO薄膜的超导性能比较发现,虽然Y_(0.5)Gd_(0.5)BCO薄膜的临界转变温度(T_c)(约为90.5 K)较YBCO和GdBCO薄膜有所下降,但是在65K、自场下,Y_(0.5)Gd_(0.5)BCO薄膜具有最高的临界电流密度(J_c)值,为4.87MA/cm~2.且随着外加磁场的增加,J_c值提高的较多.在3T的磁场下,Y_(0.5)Gd_(0.5)BCO薄膜的J_c值分别是纯GdBCO和YBCO薄膜的1.8倍和5.1倍.此外,替代还有效提高了薄膜的磁通钉扎力.     

涂层溶液粘度对SmBa_2Cu_3O_(7-x)超导薄膜结构和性能的影响

采用自主开发的无氟化学溶液沉积法在(00l)LaAlO_3单晶片上制备了SmBa_2Cu_3O_(7-x)(SmBCO)超导薄膜,研究了涂层溶液的粘度对SmBCO超导薄膜织构、微结构及超导性能的影响。通过调节前驱溶液中高分子的添加量来调控涂层溶液的粘度。结果表明,不同高分子添加量的涂层溶液制备的薄膜均具有较好的c轴单晶取向,其中高分子添加量为4%的涂层溶液制备的超导薄膜表面更加平整、致密,显示了良好的晶粒连接性。此外,该粘度的涂层溶液制备的薄膜超导转变温度为89.5K,临界电流密度(65K,自场)达到1MA/cm~2以上,显示了较好的超导电性。     

In_2O_3/Si衬底上的YBa_2Cu_3O_(7-x)高温超导薄膜的特性研究

本文介绍用直流平面磁控溅射方法制备In_2O_3导电薄膜,以该导电薄膜为缓冲层,在硅衬底上沉积YBCO高温超导薄膜。用大直径平面磁控溅射,原位退火方法制备YBCO超导薄膜,用In_2O_3缓冲层来减少YBCO薄膜和Si衬底之间的相互扩散。所制得的YBCO高温超导薄膜的零电阻温度为81K,转变温度为98K,用X光衍射(XRD)方法来分析其微结构,结果表明其微观结构是C轴择优取向。用俄歇微探针(AES)来研究YBCO和In_2O_3、In_2O_3和Si之间的相互扩散情况,结果表明In_2O_3导电缓冲层基本上阻挡住YBCO和Si之间的相互扩散。     

热处理对Bi2O3-B2O3-SiO2凝胶玻璃粉体结构与性能的影响

采用溶胶-凝胶法制备了一种Bi₂O₃-B₂O₃-SiO₂系玻璃粉体,在200 ℃、400 ℃、600 ℃和800 ℃温度下分别对凝胶玻璃粉体进行热处理,借助SEM、TEM、XRD、FT-IR、Raman、XPS、DSC、热膨胀仪及“纽扣”烧结实验分别测定了经不同温度热处理后玻璃粉体的结构与性能,分析了其结构变化对玻璃粉体转变温度T_g和烧结特性的影响。结果显示,在实验温度范围内,随热处理温度升高,Bi³⁺逐渐进入玻璃网络中,[BiO₆]八面体和[BiO₃]三角体、[BO₄]四面体和[BO₃]三角体分别与[SiO₄]四面体以顶角相连的方式构建玻璃网络结构。O1s和Bi4f的电子结合能逐渐增大,B1s的电子结合能减小,玻璃网络结构稳定性增强,导致玻璃转变温度T_g及玻璃膨胀软化点温度T_d升高、 润湿性降低且热膨胀系数略有降低。经600 ℃热处理后,玻璃粉体具有较优的烧结性能,T_g、T_d分别约为485 ℃及542 ℃,热膨胀系数α约为7.067×10-6/℃。     

溶胶-凝胶法制备Bi0.975La0.025Fe0.975Ni0.025O3铁电薄膜的结构及物理性能

采用溶胶-凝胶法在Pt/Ti/SiO_2/Si(111)衬底上制备了Bi_(0.975)La_(0.025)Fe_(0.975)Ni_(0.025)O_3(BLFNO)铁电薄膜。利用X射线衍射(XRD)、原子力显微镜(AFM)及其压电模式(PFM)对薄膜的晶体结构、表面形貌以及铁电畴结构进行了研究。研究发现,BLFNO为结晶良好的钙钛矿结构多晶薄膜,且薄膜表面颗粒生长均匀。PFM测试图显示铁电薄膜在自发极化下的铁电畴结构清晰,铁电电容器具有良好的铁电性能。应用铁电测试仪对Pt/BLFNO/Pt电容器进行测量,得到了饱和性良好的电滞回线。在828kV/cm的外加电场下,Pt/BLFNO/Pt电容器的剩余极化强度为74.3μC/cm~2,表明La、Ni的共掺杂没有明显抑制铁电电容器的剩余极化强度,铁电电容器具有良好的铁电性能。漏电流研究结果表明,La、Ni元素的共掺杂有效降低了薄膜的漏电流密度,在277.8kV/cm外加电场下漏电流密度在10-4 A/cm2量级,明显小于纯BFO薄膜的漏电流密度。正半支漏电流曲线满足SCLC导电机制,对于负半支曲线,当电场强度大于22.2kV/cm时,同样遵循SCLC导电机制;但是,当电场强度小于22.2kV/cm时,曲线斜率约为4.8,表明参与导电贡献的电子数较多,归因于极浅陷阱俘获的电子在外加电场作用下参与了导电行为。室温下磁滞回线测试结果表明BLFNO薄膜具有反铁磁性质。     

纳米-Al2O3/SiO2加入量对MgO-Al2O3-SiO2复相陶瓷烧结机理的影响

为了探究纳米-Al₂O₃/SiO₂加入量对MgO-Al₂O₃-SiO₂复相陶瓷烧结行为的作用机理。以微米级MgO、纳米级Al₂O₃和SiO₂为主要原料制备陶瓷基复合材料。通过XRD和 SEM等检测手段对烧后试样的物相组成和微观结构进行测试与表征,重点研究Al₂O₃/SiO₂的加入对复相陶瓷物相组成、微观结构及烧结性能的影响。结果表明:随着Al₂O₃/SiO₂加入量的增大,试样烧后相对密度和烧后线变化率呈先增大后减小再增大的趋势,加入15%Al₂O₃/SiO₂(质量分数)的试样经1 500 ℃烧结后,其相对密度可以达到94%。引入的Al₂O₃/SiO₂与基体中的MgO生成镁铝尖晶石与镁橄榄石相,原位反应伴随的体积膨胀,抵消部分烧结过程中的体积收缩。Al₂O₃/SiO₂加入量为75%(质量分数)的试样经1 400 ℃烧结后,基体中有大量堇青石相生成,随着煅烧温度提高到1 500 ℃,堇青石分解所产生的高温液相促进了试样的烧结收缩。     

Application of accelerated carbonation with a combination of Na2CO3 and CO2 in cement-based solidification/stabilization of heavy metal-bearing sediment

The efficient remediation of heavy metal-bearing sediment has been one of top priorities of ecosystem protection. Cement-based solidification/stabilization (s/s) is an option for reducing the mobility of heavy metals in the sediment and the subsequent hazard for human beings and animals. This work uses sodium carbonate as an internal carbon source of accelerated carbonation and gaseous CO₂ as an external carbon source to overcome deleterious effects of heavy metals on strength development and improve the effectiveness of s/s of heavy metal-bearing sediment. In addition to the compressive strength and porosity measurements, leaching tests followed the Chinese solid waste extraction procedure for leaching toxicity – sulfuric acid and nitric acid method (HJ/T299-2007), German leaching procedure (DIN38414-S4) and US toxicity characteristic leaching procedures (TCLP) have been conducted. The experimental results indicated that the solidified sediment by accelerated carbonation was capable of reaching all performance criteria for the disposal at a Portland cement dosage of 10 wt.% and a solid/water ratio of 1:1. The concentrations of mercury and other heavy metals in the leachates were below 0.10 mg/L and 5 mg/L, respectively, complying with Chinese regulatory level (GB5085-2007). Compared to the hydration, accelerated carbonation improved the compressive strength of the solidified sediment by more than 100% and reduced leaching concentrations of heavy metals significantly. It is considered that accelerated carbonation technology with a combination of Na₂CO₃ and CO₂ may practically apply to cement-based s/s of heavy metal-bearing sediment.     

Liquidus Diagram of the Ba-Y-Cu-O System in the Vicinity of the Ba2YCu3O6+x Phase Field

This paper describes the melting equilibria in the vicinity of the high T_c phase Ba₂YCu₃O_6+x, including evidence for two Ba-Y-Cu-O immiscible liquids. Melting equilibria have been investigated in purified air using a combination of differential thermal analysis (DTA), thermogravimetric analysis (TGA), powder x-ray diffraction (XRD), MgO wick entrapment of liquid for analysis, scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDS), and hydrogen reduction for determination of copper oxidation state. For relatively barium-rich compositions, it was necessary to prepare the starting materials under controlled atmosphere conditions using BaO. A liquidus diagram was derived from quantitative data for the melts involved in various melting reactions. In general the 1/2(Y₂O₃) contents of the melts participating in these equilibria were low (mole fraction <4 %). The primary phase field of Ba₂YCu₃O_6+x occurs at a mole fraction of <2.0 % 1/2Y₂O₃ and lies very close along the BaO-CuO_x edge, extending from a mole fraction of ≈43 % CuO to a mole fraction of ≈76 % CuO. It is divided by a liquid miscibility gap and extends on either side about this gap. The topological sequence of melting reactions associated with the liquidus is presented as a function of temperature. Implications for the growth of Ba₂YCu₃O_6+x crystals are discussed.     

Sn0.94Sc0.06P2O7的合成及其中温电性能研究

采用固相法合成了Sn0.94Sc0.06P2O7。XRD测试结果表明Sn0.94Sc0.06P2O7表现为单一立方SnP2O7相结构。采用电化学工作站对样品的中温电性能(50~250℃)进行了研究。结果表明,样品在湿润H2气氛中200℃下,电导率达到最大值(2.8×10-2 S·cm-1)。以样品为固体电解质组装氢-空气燃料电池,性能测试表明,在150℃时,其最大输出功率密度为25.02mW·cm-2(厚度:1.7mm),表明Sn0.94Sc0.06P2O7是一种潜在的中温燃料电池的电解质材料。     

Ba(OH)2 Equilibria in the System Ba-O-H-F,With Application to the Formation of Ba2YCu3O6.5 + x From BaF2-Precursors

The ex situ process for fabricating Ba₂YCu₃O_{6.5 + x} superconducting tapes from BaF₂- based precursors involves a hydration/oxidation reaction at ≈730 °C to 750 °C generally written as: (2BaF2+Y+3Cu)(amorphous)+(2H2O+2.25O2)(g)→Ba2YCu3O6.5+x(s)+4HF(g).However, microscopic observations of partially processed films suggest the presence of a transient liquid phase during conversion. Alternatively, the conversion reaction can be rewritten as the sum of several intermediate steps, including the formation of a barium hydroxide liquid: (BaF2)(amorphous)+2H2O(g)→Ba(OH)2(liq)+2HF(g).To evaluate the possibility of a hydroxide liquid conversion step, thermodynamic calculations on the stability of Ba(OH)₂(liq) have been completed from 500 °C to 900 °C at 0.1 MPa p_total. Based on currently available data, the calculated phase diagrams suggest that a viable hydroxide reaction path exists in the higher part of this temperature range. The calculations indicate that Ba(OH)₂(liq) may be stable at log p_H2O (Pa) values from ≈4 to 5, provided log p_HF (Pa) values can be maintained below 0 to −1. Limited experimental confirmation is provided by results of an experiment on BaF₂(s) at 815 °C, 0.1 MPa p_H2O, in which essentially all F at the surface was replaced by O. It is therefore possible that processing routes exist for producing Ba₂YCu₃O_{6.5 + x} based on the presence of a Ba(OH)₂ liquid, which might have an effect on conversion rates and texturing in the superconducting film.     

La2O3、Nd2O3、Y2O3对高岭石高温相变动力学的影响

利用综合热分析技术、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)研究了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温条件下转变成莫来石过程的作用,并采用Kissinger方程、Ozawa方程以及JMA修正方程(Ⅰ)和(Ⅱ)分析了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温相变动力学的影响。结果表明:3种稀土氧化物的掺入对高岭石的相变动力学参数产生了影响,相变活化能和频率因子与未掺入稀土氧化物的高岭石相比有所降低,析晶方式则未发生变化,均属于体积晶化。对比掺入3种稀土氧化物的高岭石相变活化能和频率因子可以看出,Y_2O_3对于高岭石高温条件下相变的促进作用最为明显,相变活化能最低。稀土氧化物对于高岭石高温相变产物影响不大,主晶相为莫来石相,次晶相为方石英相,但稀土氧化物的掺入使得方石英相的结晶度明显提高。     

凝胶-燃烧法制备LaNiO3和La2NiFeO6光催化剂的比较研究

采用凝胶-燃烧法制备稀土单钙钛矿型LaNiO_3和双钙钛矿型La_2NiFeO_6光催化剂,利用X射线衍射、BET、红外光谱、扫描电镜进行了表征,并在可见光下以亚甲基蓝为模拟降解物进行了光催化研究。结果表明:钙钛矿LaNiO_3的结构是斜方六面体,而双钙钛矿La_2NiFeO_6的结构是立方体;La_2NiFeO_6的光催化活性高于LaNiO_3,这与二者之间的结构和表面性质的差异有关。     

基于SnO2/Fe3O4粒子电极的三维电极体系的电催化性能

通过水热法合成复合金属氧化物SnO_2/Fe_3O_4粒子电极,然后采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、磁滞回线等技术分别对粒子电极的晶体组分、形貌、元素组成和分子结构以及粒子电极的磁性特征进行表征。采用循环伏安法分析了三维电极系统的电化学性能,并进行了电催化氧化降解罗丹明B(RhB)的实验。结果表明,SnO_2/Fe_3O_4粒子电极负载稳定、导电性强、便于回收再利用,有利于电催化氧化降解反应。三维电极降解罗丹明B的析氧电流高于其他电极体系,电催化活性效果明显,90min内罗丹明B的降解率为100%、TOC去除率为83%,反应中产生的·OH是降解有机物的主要活性基。粒子电极在重复利用5次的情况下,对罗丹明B的降解率仍保持93%以上、TOC去除率保持在77%以上,具有稳定的电催化性能。