TFA-MOD方法制备YBCO超导薄膜研究

采用TFA-MOD方法在LaAlO3(001)单晶基片上制备了性能良好的YBCO超导薄膜:临界电流密度(Jc)可达3MA/cm2(77K,0T),超导转变温度Tc≈90K,转变宽度ΔTc=0.5K,其一次涂层厚度达338nm.通过X射线衍射(XRD)分析表明YBCO具有纯c-轴取向、无a-轴取向的晶粒存在.ω扫描分析表明该YBCO薄膜具有很好的面外外延性,其摇摆曲线的半高宽(FWHM)为0.653°. 用SEM分析也表明膜的表面无裂纹存在,表面平整,没有a轴晶粒生长.     

钛酸锶衬底表面改性对YBCO高温超导薄膜性能的影响北大核心CSCD

YBa_2Cu_3O_(7-x)(YBCO)高温超导材料在高温高场中具有比较高的临界电流密度,因此具有较好的应用前景.通过研究YBCO高温超导薄膜,以提高它的载流能力和超导性能是市场应用的迫切需要.文中所研究的钛酸锶(SrTiO_3)衬底,作为一种钙钛矿结构,不仅具有良好的化学和热稳定性,而且与YBCO高温超导薄膜具有较小的晶格失配度.通过酸腐蚀法和无酸腐蚀处理钛酸锶SrTiO_3(100)(STO)衬底,运用原子力显微镜观察了两种衬底处理方法对钛酸锶衬底表面结构的影响.并在其上用三氟乙酸盐金属有机沉积法(TFA-MOD)制备出临界密度达到约2.50~3.00 MA/cm^2的YBCO高温超导薄膜.通过四引线法表征YBCO高温超导薄膜的Tc达到了均约93K.通过扫描电子显微镜(SEM)分析了衬底处理技术的不同对其表层生长的YBCO高温超导薄膜形貌的影响.通过X射线衍射仪(XRD)固定方位角法表征了不同的衬底处理技术对薄膜内的残余应力的影响.     

钛酸锶衬底表面改性对YBCO高温超导薄膜性能的影响

YBa_2Cu_3O_(7-x)(YBCO)高温超导材料在高温高场中具有比较高的临界电流密度,因此具有较好的应用前景.通过研究YBCO高温超导薄膜,以提高它的载流能力和超导性能是市场应用的迫切需要.文中所研究的钛酸锶(SrTiO_3)衬底,作为一种钙钛矿结构,不仅具有良好的化学和热稳定性,而且与YBCO高温超导薄膜具有较小的晶格失配度.通过酸腐蚀法和无酸腐蚀处理钛酸锶SrTiO_3(100)(STO)衬底,运用原子力显微镜观察了两种衬底处理方法对钛酸锶衬底表面结构的影响.并在其上用三氟乙酸盐金属有机沉积法(TFA-MOD)制备出临界密度达到约2.50~3.00 MA/cm~2的YBCO高温超导薄膜.通过四引线法表征YBCO高温超导薄膜的Tc达到了均约93K.通过扫描电子显微镜(SEM)分析了衬底处理技术的不同对其表层生长的YBCO高温超导薄膜形貌的影响.通过X射线衍射仪(XRD)固定方位角法表征了不同的衬底处理技术对薄膜内的残余应力的影响.     

MgO单晶基片上YBCO高温超导薄膜的制备

在2英寸MgO(001)单晶基片上,采用直流溅射法,通过基片高温退火,成功制备了性能优越的YBa2C3O7-δ(YBCO)双面超导薄膜,能够满足超导滤波器的设计要求。X射线衍射(XRD)分析表明经过退火的基片上生长的YBCO薄膜与基片有单一的外延取向关系;用原子力显微镜(AFM)和高能电子衍射(RHEED)分析高温退火对基片表面状况的改变。结果表明制备的YBCO薄膜具有很好的超导电性,薄膜临界电流密度Jc(77K,0T)≈2.5×106A/cm2,微波表面电阻Rs(10GHz,77K)≈0.16mΩ。     

化学溶液沉积快速制备YBCO超导薄膜研究

用传统的三氟乙酸盐—金属有机化合物热解法（简称TFA-MOD）来制备YBCO超导薄膜,由于制备时间长,不利于工业化.本文通过加入高沸点螯合剂二乙醇胺来改善前驱液性质,然后采用高温烧结一步法快速制备出完整的YBCO超导薄膜.制备的YBCO超导薄膜致密、几乎无a轴晶粒,YBCO（00l）峰具有立方取向,没有其他杂相峰.同时...     

采用MOD法在LAO上制备YBCO超导薄膜的Raman光谱研究

研究了TFA-MOD法在铝酸镧基体上制备YBCO超导薄膜时不同初始热处理温度对薄膜的影响。通过XRD、Ram an光谱和SEM等手段,对生长过程中的YBCO超导薄膜结构进行表征、分析,探讨了YBCO的生长机制。     

沉积温度对YBCO薄膜取向的影响

采用脉冲激光沉积技术(PLD)在SrTiO3(100)单晶衬底上制备YBCO薄膜,用X射线对薄膜的取向和织构进行表征,用扫描电子显微镜(SEM)对薄膜的表面形貌进行观察.实验主要研究了衬底温度对薄膜外延取向的影响,结果表明在770℃温度下制备的YBCO有较多的a轴晶粒生成,在800℃温度下制备的YBCO是纯的c轴取向,且平均面内φ扫描半高宽(FWHM)为1.2°,超导转变宽度(△Tc)为0.9K.     

Eu2CuO4缓冲层和YBCO超导薄膜的制备及研究

本文用脉冲激光淀积法在LaAlO3(100)基片上外延生长Eu2CuO4薄膜缓冲层和YBCO超导薄膜,用X射线衍射扫描分析表明ECO薄膜为c轴取向.     

在SrTiO3基底上用溶胶-凝胶法制备CeO2缓冲层

CeO2是目前被广泛研究的能与YBCO超导材料有良好晶格匹配的缓冲层材料,溶胶-凝胶法是一种成本低廉的非真空制备薄膜的方法,如果能用这种方法制备质量良好的CeO2薄膜,则可降低YBCO覆膜导体制备的成本.本文通过一种以Ce(NO3)3*6H2O为先驱液相的溶胶体系,在SrTiO3(100)基底上用溶胶-凝胶方法制备了CeO2薄膜.研究了不同热处理温度对CeO2薄膜晶粒生长的影响.为了避免CeO2薄膜表面微裂纹的形成,研究了在烘干和热解过程中所采用的有效方法.利用TGA,DSC,SEM和XRD,对CeO2薄膜的吸热放热过程、表面形貌和相组成进行了分析.结果表明,该溶胶经旋涂、120℃下烘干以及直接300℃热解后,再在600℃下烧结,可制得无裂纹和孔洞、表面质量良好的CeO2薄膜.     

TFA-MOD法制备YBCO薄膜生长速率研究

采用原位电阻法对TFA-MOD法高温热处理阶段YBCO薄膜生长速率进行了研究。实验结果和分析表明原位电阻测量法是一种估算YBCO层生长速率的有效方法,不同条件下的测量结果表明薄膜生长速率随管式炉内的温度、水分压、气体流量的上升而明显增加,但随薄膜面积的增加而减小。实验结果为进一步探索和优化热处理过程提供了重要的基础。     

金属有机溶剂法Y1Ba2Cu3O7-δ超导薄膜的Ce掺杂效应

通过三氟乙酸盐-金属有机物沉积方法（TFA-MOD）研究了Ce掺杂对钇钡铜氧（YBCO）超导薄膜性能的影响.观察到10 mol%Ce掺杂使YBCO超导薄膜的c轴取相降低,出现明显的a轴晶粒,薄膜表面变得粗糙.尽管超导临界温度稍有减小,其超导临界电流密度（Jc）在高磁场下性能获得了有效提高,当外磁场强度达到2T时,超导薄...     

前驱膜形貌对TFA-MOD技术生长YBCO超导薄膜的影响

本文采用三氟乙酸盐-金属有机沉积(TFA-MOD)技术在LaAlO3(00l)单晶基片上、在不同的低温热处理条件下制备出不同形貌的前驱膜.从金相显微镜(OM)和扫描电镜(SEM)观察可以看出,低温预分解时造成前驱膜的形貌不完整性在高温处理后并没有消除.对高温热处理后的YBCO成相膜用X射线衍射进行了物相定性分析,用Jc-Scan Leipzig系统对超导薄膜进行了超导性能分析.结果表明,前驱膜的形貌不完整性造成高温成相阶段样品杂相出现和超导性能降低.经过对低温热处理条件的优化,得到表面形貌完整的前驱膜,避免了高温成相阶段杂相出现,提高了涂层导体的超导性能,Jc可以超过1.5MA/cm2.     

掺杂Y2O3和BaCeO3提高MOD-YBCO超导性能的研究

本文通过在前驱液中添加过量钇盐和铈的有机盐,采用三氟乙酸盐-金属有机沉积法(TFA-MOD) 在铝酸镧单晶基体上制备了含有纳米氧化钇和纳米铈酸钡的YBCO薄膜. 与纯YBCO薄膜相比,掺杂Y₂O₃/BaCeO₃的YBCO膜的临界转变温度几乎保持不变,为91 K左右. 而掺杂Y₂O₃/BaCeO₃的YBCO膜的临界电流密度达到5.0 MA/cm² (77 K, 0T), 是纯YBCO膜临界电流密度的1.5倍.薄膜中的Y₂O₃和BaCeO₃可能在YBCO内部起到了 有效的钉扎磁通作用. 关键词： 钇钡铜氧薄膜 2O₃和纳米BaCeO₃')" href="#">纳米Y₂O₃和纳米BaCeO₃ 磁通钉扎 三氟乙酸盐-金属有机沉积     

Strong flux pinning enhancement in YBa2Cu3O7-x films by embedded BaZrO3 and BaTiO3 nanoparticles

YBa2Cu3O7-x (YBCO) films with embedded BaZrO3 and BaTiO3 nanoparticles were fabricated by metalorganic deposition using trifluoroacetates (TFA-MOD). Both X-ray diffraction and transmission electron microscopy revealed that these BaZrO3 and BaTiO3 nanoparticles had random orientations and were distributed stochastically in the YBCO matrix. The unique combined microstructure enhances the critical current density (Jc) of the BaZrO3/BaTiO3 doped-YBCO films, while keeping the critical transition temperature (Tc) close to that in the pure YBCO films. These results indicate that BaZrO3 and BaTiO3 nanoparticles provide strong flux pinning in YBCO films.     

前驱液成分对TFA-MOD法制备YBa2Cu3O7-x薄膜超导性能的影响

采用三氟乙酸盐-金属有机沉积法(TFA-MOD)在铝酸镧单晶基体上制备了YBa₂Cu₃O_7-x (YBCO)超导薄膜.通过改变前驱液的成分,研究了金属元素的不同化学计量比对YBCO薄膜的结构和性能的影响.结果表明,按照钇盐Y(CH₃COO)₃与钡盐Ba(CH₃COO)₂的比例为Y ∶Ba=1 ∶1.5时所制备的YBCO薄膜的临界电流密度比严 关键词： 三氟乙酸盐-金属有机沉积 钇钡铜氧薄膜 前驱液成分 磁通钉扎     

Strongly enhanced flux pinning in the YBa_2Cu_3O_(7-X) films with the co-doping of Ba TiO_3 nanorod and Y_2O_3 nanoparticles at 65 K

YBa2Cu3O7-x(YBCO) films with co-doping BaTiO3(BTO) and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates(TFA-MOD). The properties of the BTO/Y2O3co-doped YBCO films with different excess yttrium have been systematically studied by x-ray diffraction(XRD), Raman spectra, and scanning electron microscope(SEM). The optimized content of yttrium excess in the BTO/Y2O3co-doped YBCO films is 10 mol.%, and the critical current density is as high as ~ 17 mA/cm2(self-field, 65 K) by the magnetic signal. In addition, the Y2Cu2O5 was formed when the content of yttrium excess increases to 24 mol.%, which may result in the deterioration of the superconducting properties and the microstructure. The unique combination of the different types of nanostructures of BTO and Y2O3 in the doped YBCO films, compared with the pure YBCO films and BTO doped YBCO films, enhances the critical current density(JC) not only at the self-magnetic field, but also in the applied magnetic field.     

Microstructure of YBCO thin films prepared by TFA-MOD method

The microstructure of the recently developed coated conductors was investigated by using electron back scatter diffraction pattern (EBSP). We prepared TFA (trifluoroacetates)-MOD (metal organic deposition) derived YBa₂Cu₃O_7−x (YBCO) films on CeO₂/LaMnO₃/IBAD-MgO/Gd₂Zr₂O₇/Hastelloy C276 substrates of 1 cm-width. The EBSP observation showed that there was a difference of surface microstructure between the midsection and the end of TFA-MOD YBCO film layer in the direction of width. This is attributed not to the local difference of the biaxial texture of CeO₂ top layer but to the local difference of growth condition during TFA-MOD process.     

Study on reaction mechanism of YBa2Cu3O7-x film by TFA-MOD process

This paper systematically investigates the intermediate phases of YBa2Cu3O7-x (YBCO) film prepared by metalorganic deposition method using trifluoroacetates (TFA-MOD). According to x-ray diffraction and Raman analyses, the precursor film decomposed in a mixture of BaF2, Y2O3 and CuO after the pyrolysis process. Then these intermediate phases converted into tetragonal YBa2Cu3O6.5 at about 725°C. The influence of water vapour pressure on the YBa2Cu3O7-x film growth on LaAlO3 single-crystal substrates was also studied. The films prepared at low water vapour pressures (40-140 hPa) showed poor electrical performance due to the a-axis grain structure and impurity phases. However, the films prepared at 190 hPa exhibited the highest critical temperature of 90 K and the highest Jc of 3.8 MA/cm2, which was attributed to the formation of a purer YBCO phase and stronger biaxial texture.     

Effect of air humidity on the microstructure and properties of large-area YBa2Cu3O7−x films by TFA-MOD process

Large-area YBa₂Cu₃O_7?x (YBCO) films had been successfully fabricated on LaAlO₃ (LAO) substrate by metalorganic deposition using trifluoroacetates (TFA-MOD) and the effect of air humidity on the structure and properties of YBCO films was systematically investigated. The precursor coating process was performed in the air humidity range of 70–40%. According to the X-ray diffraction (XRD) and scanning electron microscopy (SEM) images, the films prepared at high air humidity showed poor electrical performance due to large pores and impurity phases. In contrast, dense, homogeneous and epitaxially grown YBCO films prepared at low air humidity with the critical current densities of 3.8–5.0 MA cm^?2 at 77 K had been obtained.